Automatic Transmission Diagnosis - 4l60-e Cadillac Escalade GMT400

APPLICATION

4L60-E TRANSMISSION APPLICATIONS

DESCRIPTION & OPERATION

The Hydra-Matic 4L60-E transmission uses 2 electric shift solenoids to control transmission upshifts and downshifts. In addition, a pressure control (force motor) solenoid controls hydraulic line pressure, and a Torque Converter Clutch (TCC) solenoid controls TCC application. A TCC Pulse Width Modulated (PWM) solenoid is used to control fluid acting on converter clutch valve, which then controls TCC apply and release. A 3-2 control solenoid modulates hydraulic pressure for the 2-4 band and 3-4 clutch to improve 3-2 downshift. Solenoids are turned on and off by Powertrain Control Module (PCM) on passenger cars and trucks with 2.2L engine, or by Vehicle Control Module (VCM) on all other light trucks and vans.

PCM/VCM receives signals from various transmission sensors. Sensors include engine speed and throttle position, transmission speed, hydraulic pressure and transmission fluid temperature. PCM/VCM has on-board self-diagnostics to help identify any parts or circuits which may need further testing.

Shift solenoid holds hydraulic pressure (solenoid on) or releases hydraulic pressure (solenoid off). This action controls shift valves inside valve body. By switching one or both solenoids on or off, different combinations of clutches, sprags and bands are operated. See SHIFT SOLENOID OPERATION (4L60-E) table under COMPONENT TESTS.

Line pressure control system compensates for normal wear of transmission components during upshifts in order to maintain optimal shift quality during life of transmission. PCM/VCM uses "adaptive learning" to maintain acceptable upshift times by adjusting line pressure. PCM/VCM compares actual "acceptable" shift time to calibrated desired shift time and calculates difference. An "acceptable" shift is considered valid if no inconsistent vehicle operations (A/C compressor cycling or extreme throttle changes) occurred during upshift. Line pressure is either increased or decreased depending on duration of time for upshift.

PCM/VCM

Passenger cars and light trucks with 2.2L, 4.8L and 5.3L engines are equipped with a Powertrain Control Module (PCM). All other light trucks and vans are equipped with a Vehicle Control Module (VCM). For PCM/VCM locations, see PCM/VCM LOCATIONS table.

PCM/VCM controls TCC, pressure control solenoid (hydraulic pressure), PWM solenoid and shift solenoids 1-2 and 2-3. In addition, PCM/VCM also controls ignition, fuel and emission devices related to engine.

PCM/VCM receives electronic input signals from sensors and switches. These signals help PCM/VCM determine when to operate various relays and solenoids related to engine and transmission components.

PCM/VCM LOCATIONS

LIMP-IN MODE

If sensor input signals are missing or inadequate for transmission operation, PCM will output preset operating signals to transmission. This mode will keep vehicle operational and allow it to be driven, with reduced transmission function and performance, to a repair facility. Malfunction Indicator Light (MIL) may light if malfunction occurs. Vehicle should not be driven for extended periods in limp-in mode.

Introduction

PCM/VCM controls converter clutch lock-up, upshifts and downshifts based on transmission temperature, system voltage, throttle position, transmission oil pressure switches (5) and transmission output and input (engine) speed sensors. (Scheme 9) System includes several other sensors and switches that are used for engine control (gasoline engines). For additional information and testing of engine components, see appropriate article in ENGINE PERFORMANCE.

Transmission Fluid Pressure (TFP) Manual Valve Position Switch

TFP manual valve position switch consists of 5 pressure switches and Transmission Fluid Temperature (TFT) sensor. Two pressure switches are normally closed and 3 are normally open. TFP manual valve position switch is mounted to valve body. (Scheme 9)

Shift Solenoids 1-2 & 2-3

Transmission shifting is performed by 2 electric shift solenoids. Both solenoids are located on valve body. (Scheme 9) Ignition power is supplied to each solenoid by transmission fuse. Solenoid 1-2 controls hydraulic pressure to 1-2 shift valve. Solenoid 2-3 controls hydraulic pressure to 2-3 shift valve.

Note. The 3-4 shift valve is directly controlled by hydraulic circuits in valve body.

Pressure Control Solenoid

Transmission Adaptive Pressure (TAP) values may require to be reset if one of the following repairs has been performed

1. Transmission overhaul or replacement.
2. Repair or replacement of an apply or release component (band, clutch, piston and/or servo).
3. Repair or replacement of a component or assembly which directly affects transmission line pressure.

To reset TAP values, see CLEARING & RESETTING TAP VALUES under COMPONENT TESTS.

Pressure control (force motor) solenoid has a spool valve and operates pressure regulator valve. (Scheme 9) PCM/VCM sends a frequency signal to pressure control solenoid to regulate hydraulic line pressure. Frequency signal (duty cycle) is measured with a dwell meter or lab scope. When duty cycle is zero, line pressure is at maximum, and pressure control solenoid draws zero amps. When duty cycle is 60 percent, line pressure is at minimum, and pressure control solenoid draws 1.1 amps at 4.5 volts.

TCC Solenoid

This solenoid is used to control TCC apply valve. PCM/VCM sends a frequency signal to TCC solenoid to gradually apply or release TCC. (Scheme 9)

3-2 Control Solenoid

PCM/VCM modulates current (duty cycle) to control 3-2 control solenoid. The 3-2 control solenoid is off in first gear. In all other gears, 3-2 control solenoid is 90 percent on. Hydraulic pressure is regulated to smoothly release 3-4 clutch and 2-4 band during 3-2 downshift.

TCC PWM Solenoid

TCC PWM solenoid is used to control fluid acting on converter clutch valve, which then controls TCC apply and release. (Scheme 9) TCC PWM solenoid is used to provide smooth engagement of torque converter clutch by operating with a duty cycle on time of less than 50 percent.

SHIFT SOLENOID OPERATION (4L60-E)

Scheme 9

SELF-DIAGNOSTIC SYSTEM

Note. Faulty engine sensors and actuators may cause transmission related DTCs or driveability problems. Engine faults and related DTCs must be diagnosed and repaired before transmission codes are repaired. For additional information on diagnosing and repairing engine related PCM/VCM trouble codes, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.

PCM/VCM constantly monitors all electrical circuits. If PCM/VCM detects circuit problems or sensors out of range, it will record a Diagnostic Trouble Code (DTC). If problem continues for a predetermined time, Malfunction Indicator Light (MIL) will glow.

If MIL is on all the time, DTC(s) are currently being detected. If MIL is off, but PCM/VCM had detected a circuit or sensor problem, DTC(s) will be stored in computer memory.

Stored DTCs may be retrieved from PCM/VCM memory using a scan tool. DTCs cannot be retrieved by grounding 16-pin Data Link Connector (DLC).

Hard Failures

Most hard failures cause MIL to illuminate and remain on until malfunction is repaired. If MIL illuminates and remains on (light may flash) during vehicle operation, cause of malfunction must be determined.

If a sensor fails, PCM/VCM will use a substitute value in its calculations to continue engine and/or transmission operation. In this condition, vehicle is functional, but it will most likely display degraded driveability. See LIMP-IN MODE .

Intermittent Failures

Intermittent failures cause MIL to flicker or glow and turn off about 10 seconds after intermittent fault goes away. Corresponding DTC, however, will be retained in PCM/VCM memory. If related fault does not reoccur within 50 engine starts, DTC will be erased from PCM/VCM memory. Intermittent failures may be caused by sensor, connector or wiring related problems.

PRELIMINARY INSPECTION

Note. The preliminary inspection is very important and should be performed carefully and thoroughly, as it can often fix a problem without requiring further diagnosis.

1. Check transmission fluid level and condition. Inspect all wiring harnesses and connections leading to transmission. Verify brake system is operational and not dragging.
2. Check all vacuum hoses for correct routing, restrictions, cuts or other damage. Inspect difficult-to-see vacuum hoses beneath air cleaner assembly and other engine components.
3. Inspect all engine compartment wiring for proper connections. Check wires for pinched or chafed spots, as well as contact with sharp edges or exhaust manifolds.
4. Repair any problems as necessary. If no problems are found during preliminary inspection, begin diagnosis of transmission electronic control system. See «DIAGNOSTIC PROCEDURE»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) under DIAGNOSIS & TESTING.

NO DATA LINK CONNECTOR (DLC) DATA

If scan tool does not display PCM/VCM data, see DLC DIAGNOSIS OR NO SCAN TOOL DATA under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.

NO MALFUNCTION INDICATOR LIGHT (MIL)

If MIL does not illuminate, see MIL INOPERATIVE or MIL CIRCUIT CHECK under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.

CLEARING & RESETTING TAP VALUES

Using scan tool, clear and reset TAP values. Follow scan tool manufacturer's instructions. Start engine and allow to reach normal operating temperature with transmission in Park. Ensure all accessories are off. Apply brakes and shift transmission into Drive. Allow engine to idle for 2 minutes. Perform road test for 5-7 miles. Operate vehicle under normal conditions. Avoid extreme acceleration. Once road test is complete, allow engine to return to idle. Place transmission in PARK. Allow engine to idle for 1 minute. Turn engine off.

COMPONENT & WIRING HARNESS RESISTANCE CHECK

1. Install Jumper Harness (J-39775) to transmission 20-pin connector. Using an ohmmeter, measure resistance between specified terminals for each component. (Scheme 10) Compare resistance reading to known values. See «TRANSMISSION COMPONENT RESISTANCE SPECIFICATIONS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) table.
2. If resistance reading is okay, go to next step. If resistance reading is not okay, disconnect wiring harness at component and measure component resistance. Replace component if resistance is not as specified. If resistance is as specified, repair wiring harness between component and 20-pin connector.
3. Measure resistance between ground and each terminal at transmission 20-pin connector. (Scheme 10) Resistance should be more than 250 k/ohms for each solenoid and more than 10 megohms for fluid temperature sensor and vehicle speed sensor. Resistance for fluid temperature sensor will vary with temperature. If resistance is within specification, problem is intermittent. If resistance is low, disconnect wiring harness at component.
4. Measure resistance between component terminals and ground. If resistance is low, replace component. If resistance is high, inspect wiring harness for short to ground. Repair as necessary.

TRANSMISSION COMPONENT RESISTANCE SPECIFICATIONS

Scheme 10

1. Install Jumper Harness (J39775) to transmission 20-pin connector. Using DVOM, measure resistance between terminal "N" of transmission 20-pin connector and ground. (Scheme 10) If resistance is less than 50 k/ohms, go to next step. If resistance is more than 50 k/ohms, go to step 3.
2. Disconnect TFP manual valve position switch connector. Measure resistance between terminal "C" at TFP manual valve position switch and ground. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e). If resistance is more than 50 k/ohms, go to step 16. If resistance is less than 50 k/ohms, replace TFP manual valve position switch.
3. Measure resistance between terminal "R" of transmission 20-pin connector and ground. If resistance is less than 200 ohms, go to step 5. If resistance is more than 200 ohms, go to next step.
4. Disconnect TFP manual valve position switch connector. Measure resistance between terminal "E" at TFP manual valve position switch and ground. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e). If resistance is less than 200 ohms, go to step 16. If resistance is more than 200 ohms, replace TFP manual valve position switch.
5. Measure resistance between terminal "P" of transmission 20-pin connector and ground. (Scheme 10) If resistance is less than 50 k/ohms, go to next step. If resistance is more than 50 k/ohms, go to step 7.
6. Disconnect TFP manual valve position switch connector. Measure resistance between terminal "D" at TFP manual valve position switch and ground. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e). If resistance is more than 50 k/ohms, go to step 16. If resistance is less than 50 k/ohms, replace TFP manual valve position switch.
7. Start engine and allow to idle. Set parking brake. Place gear selector in Reverse. Measure resistance between terminal "N" of transmission 20-pin connector and ground. If resistance is less than 200 ohms, go to next step. If resistance is more than 200 ohms, go to step 16.
8. Place gear selector in "1" (low) position. Measure resistance between terminal "N" of transmission 20-pin connector and ground. If resistance is less than 200 ohms, go to next step. If resistance is more than 200 ohms, go to step 16.
9. Place gear selector in "3" (3rd gear) position. Measure resistance between terminal "R" of transmission 20-pin connector and ground. If resistance is more than 50 k/ohms, go to next step. If resistance is less than 50 k/ohms, go to step 16.
10. Place gear selector in "D" (overdrive) position. Measure resistance between terminal "P" of transmission 20-pin connector and ground. If resistance is less than 200 ohms, go to next step. If resistance is more than 200 ohms, go to step 16.
11. Place gear selector in "2" (2nd gear) position. Measure resistance between terminal "P" of transmission 20-pin connector and ground. If resistance is more than 50 k/ohms, go to next step. If resistance is less than 50 k/ohms, go to step 16.
12. Turn ignition off. Measure resistance between terminal "L" and terminal "M" at transmission 20-pin connector. If TFT sensor resistance is 3088-3942 ohms at 68°F (20°C) or 159-198 ohms at 212°F (100°C), go to next step. If TFT sensor resistance is not as specified, go to step 14.
13. Measure resistance between terminal "L" of transmission 20-pin connector and ground, and between terminal "M" of transmission 20-pin connector and ground. If both resistance readings are more than 10 megohms, problem is intermittent. Go to step 16. If both resistance readings are less than 10 megohms, go to next step.
14. Disconnect TFP manual valve position switch connector. Measure resistance between terminal "A" and terminal "B" at TFP manual valve position switch. If TFT sensor resistance is 3088-3942 ohms at 68°F (20°C) or 159-198 ohms at 212°F (100°C), go to next step. If TFT sensor resistance is not as specified, replace TFP manual valve position switch.
15. Measure resistance between terminal "A" of TFP manual valve position switch and ground, and between terminal "B" of TFP manual valve position switch and ground. If both resistance readings are more than 10 megohms, go to next step. If both resistance readings are less than 10 megohms, replace TFP manual valve position switch.
16. Check for short or high resistance in TFP manual valve position switch circuits. Check for poor connections at transmission 20-pin connector and at TFP manual valve position switch. Check for bent, backed out or damaged terminals, or poor terminal tension. If diagnosing for intermittent problem, wiggle wiring harness while observing test equipment for change in value. If short or high resistance is found, verify repair, then repeat test procedure. If short or high resistance is not found, check for open or short to ground in circuits between TFP manual valve position switch and PCM. Replace wiring harness as necessary. If circuits are okay, replace TFP manual valve position switch.

2ND GEAR START SWITCH (CAMARO & FIREBIRD - 3.8L)

Note. Camaro and Firebird with 3.8L engine are equipped with a 2nd gear start switch. Switch does not set a DTC. However, this component may affect transmission performance.

Circuit Description

The 2nd gear start switch, located on instrument panel, above radio, enables driver to select a 2nd gear start for increased traction during slippery driving conditions. When driver selects 2nd gear, 2nd gear start switch input signal momentarily toggles to zero volts. PCM turns on 2nd gear start mode indicator light, located within 2nd gear start switch, and de-energizes 1-2 shift solenoid, enabling 2nd gear.

During light and medium acceleration conditions, vehicle starts in 2nd gear when 2nd gear is selected. However, 2nd gear starts are overridden and 1st gear starts occur if a hard acceleration condition (wide open throttle) is requested. Normal 1st gear start mode is obtained by toggling 2nd gear start switch again, or when ignition switch is cycled off, then on.

Diagnostic Procedure

Note. If PCM replacement is necessary, ensure new PCM is reprogrammed. See COMPUTER RELEARN PROCEDURES article in APPLICATIONS & IDENTIFICATION.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. While cycling ignition switch from ON to OFF position, observe 2nd gear start indicator light on scan tool. If ON is displayed the first time switch is depressed, and OFF is displayed the second time switch is depressed, go to step 5 . If ON is not displayed the first time switch is depressed, and OFF is not displayed the second time switch is depressed, go to next step.
2. Install fused jumper between terminals "E" and "F" (Brown/White wire and Black/White wire) at 2nd gear start switch while observing scan tool display. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If scan tool indicates on, replace 2nd gear start switch, then go to step 7 . If scan tool indicates off, go to next step.
3. Check for open in Black/White wire between ground and 2nd gear start switch. Repair as necessary, then go to step 7 . If circuit is okay, go to next step.
4. Using a DVOM, measure voltage input at terminal "E" (Brown/White wire) at 2nd gear start switch. If voltage is present, replace PCM. Ensure PCM is reprogrammed. Go to step 7 . If no voltage is present, check for open in Brown/White wire between PCM and 2nd gear start switch. Repair as necessary, then go to step 7 . If wire is okay, replace PCM. Ensure PCM is reprogrammed. Go to step 7 .
5. Install a test light between ground and terminal "A" (Brown wire) at 2nd gear start switch. If test light is on, go to next step. If test light is off, check for open or short to ground in Brown wire between PCM and 2nd gear start switch. Repair as necessary, then go to step 7 . If wire is okay, go to next step.
6. Disconnect 2nd gear start switch connector. Check for continuity with DVOM positive lead connected to terminal "A" (Brown wire) and negative lead connected to terminal "B" (Purple/White wire) at 2nd gear start switch. If continuity does not exist, replace 2nd gear start switch, then go to next step. If continuity exists, check for open in Purple/White wire between PCM and 2nd gear start switch. Repair as necessary, then go to next step. If wire is okay, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__2nd-gear-start-switch-camaro) .
7. After repair is complete, select 2nd gear start indicator light on scan tool. If ON is displayed the first time switch is depressed and indicator light turns on, and OFF is displayed the second time switch is depressed and indicator light turns off, system is okay. If scan tool display and indicator light does not operate as indicated, repeat test.

Diagnostic Aids

If electrical circuit is okay, and 2nd gear starts are not correct, a mechanical or hydraulic malfunction may exist. Refer to HYDRA-MATIC 4L60-E OVERHAUL article for diagnosis.

DIAGNOSIS & TESTING

Note. To test electronic control of transmission solenoids, sensors and pressure switch assembly without using self-diagnostics, go to COMPONENT TESTS .

Note. Trouble codes will be recorded at various operating times. Some codes require operation of affected sensor or switch for 5 seconds; others may require operation for 5 minutes or longer at normal operating temperature, road speed and load. Therefore, some codes may not set in a service bay operational mode and may require road testing vehicle in order to duplicate condition under which code will set.

Diagnosis of computerized engine control system should be performed in the following order

1. Ensure all engine systems not related to computer system are operating properly. DO NOT proceed with testing unless all other problems have been repaired. On-Board Diagnostic (OBD) system check must be performed before using specific DTC testing procedure. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS)»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__on-board-diagnostic-obd-system-check-passenger) or «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (LIGHT TRUCKS & VANS)»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__on-board-diagnostic-obd-system-check-light) .
2. If DTCs were displayed, determine whether codes are hard or intermittent. Hard codes will cause MIL to illuminate continuously while engine is running. See «HARD OR INTERMITTENT TROUBLE CODE DETERMINATION»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__hard-or-intermittent-trouble-code-determination) . For diagnosing hard codes, proceed to appropriate DTC test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS (PASSENGER CARS)»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) or «DIAGNOSTIC TROUBLE CODE DEFINITIONS (LIGHT TRUCKS & VANS)»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . For diagnosing intermittent codes, see appropriate TROUBLE SHOOTING - NO CODES article in ENGINE PERFORMANCE.
3. If no DTCs are present and vehicle is in limp-in mode, check fused power supply circuit to transmission solenoids. Non-related transmission component system failure may cause this circuit fuse to fail. Fuses such as ERLS or SHIFT SOL fuse supply power to non-related transmission components (A/C clutch, EGR, EVAP, or ABS system) which may have caused fuse to fail.
4. If no DTCs are present and a driveability problem exists, refer to SYMPTOMS in appropriate TROUBLE SHOOTING - NO CODES article in ENGINE PERFORMANCE. Doing so will help identify proper system or component to check in appropriate SYSTEM & COMPONENT TESTING article in ENGINE PERFORMANCE.
5. After necessary repairs are made, clear DTCs, verify vehicle will enter "closed loop" operation and ensure DTC does not reset.

ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS)

Note. Only transmission-related trouble codes are listed. For engine-related DTC definitions, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. These DTCs pertain to engine performance and must be repaired first, as engine performance and related component signals will affect transmission operation and diagnosis.

The OBD system check determines

1. If Malfunction Indicator Light (MIL) operates.
2. If PCM is operating and can recognize a fault.
3. If any DTCs are stored.

OBD system check is the starting point for utilizing the self-diagnostic system for determining computer-related problems. Use of scan tool is required to perform OBD system check. Perform this test prior to performing any diagnostic procedures in DTC tests. For scan tool data values, refer to scan tool manufacturer owner's manual. After performing necessary tests as described in diagnostic system check, if no DTCs are indicated and driveability problems still exist, see appropriate TROUBLE SHOOTING - NO CODES article in ENGINE PERFORMANCE.

3.8L

1. Turn ignition on, with engine off. Observe MIL. If MIL illuminates, go to next step. If MIL does not illuminate, go to «NO MALFUNCTION INDICATOR LIGHT (MIL)»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__no-malfunction-indicator-light-mil) in SYMPTOM TESTS.
2. Turn ignition off. Connect scan tool. Turn ignition on. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to «NO DATA LINK CONNECTOR (DLC) DATA»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__no-data-link-connector-dlc-data) in SYMPTOM TESTS.
3. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article in ENGINE PERFORMANCE.
4. Using scan tool, observe DTC status for MIL REQUEST, FAIL THIS IGN, LAST TEST FAIL and HISTORY. If any DTCs are stored, save freeze frame and failure records information using scan tool CAPTURE INFO feature. Diagnose DTCs. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS (PASSENGER CARS)»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If DTCs are not present, go to next step.
5. Compare PCM data values displayed on scan tool with typical control system data values. For scan tool data values, refer to scan tool manufacturer owner's manual. If values are within limits, system is okay. If values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article in ENGINE PERFORMANCE.

5.7L (VIN G - Camaro & Firebird)

1. Connect scan tool. Turn ignition on, with engine off. If scan tool powers up, go to next step. If scan tool does not power up, go to «NO DATA LINK CONNECTOR (DLC) DATA»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__no-data-link-connector-dlc-data) in SYMPTOM TESTS.
2. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to «NO DATA LINK CONNECTOR (DLC) DATA»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__no-data-link-connector-dlc-data) in SYMPTOM TESTS.
3. Attempt to start engine. If engine starts and continues to run, go to step 5 . If engine does not start or starts and then stalls, go to next step.
4. Using scan tool, check for DTCs. If DTC P1626 is present, diagnose using appropriate test for DTC P1626. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If no DTCs are present, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article in ENGINE PERFORMANCE.
5. Using scan tool, observe DTC status for MIL REQUEST, FAIL THIS IGN, LAST TEST FAIL and HISTORY. If any DTC is stored, save freeze frame and failure records information using scan tool CAPTURE INFO feature. Diagnose DTCs. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS (PASSENGER CARS)»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If DTCs are not present, go to next step.
6. Compare scan tool engine data with typical control system data values. For scan tool data values, refer to scan tool manufacturer owner's manual. If data values are within limits, see appropriate TROUBLE SHOOTING - NO CODES article in ENGINE PERFORMANCE. If data values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article in ENGINE PERFORMANCE.

5.7L (VIN G - Corvette)

1. Connect scan tool. Turn ignition on, with engine off. If scan tool powers up, go to next step. If scan tool does not power up, go to «NO DATA LINK CONNECTOR (DLC) DATA»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__no-data-link-connector-dlc-data) in SYMPTOM TESTS.
2. If scan tool displays PCM data, go to step 4 . If scan tool does not display PCM data, go to next step.
3. Using scan tool, select DIAGNOSTIC CIRCUIT CHECK and CLASS 2 MESSAGE MONITOR. If scan tool displays any other modules as ACTIVE, go to «NO DATA LINK CONNECTOR (DLC) DATA»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__no-data-link-connector-dlc-data) in SYMPTOM TESTS. If scan tool does not display any other modules as ACTIVE, check scan tool connection. Check circuits between DLC and control module which does not communicate with scan tool. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary.
4. Attempt to start engine. If engine starts and continues to run, go to step 6 . If engine does not start or starts and then stalls, go to next step.
5. Using scan tool, check for DTCs. If DTC P1626 or P1631 is present, diagnose using appropriate test for DTC P1626 or P1631. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If no DTCs are present, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article in ENGINE PERFORMANCE.
6. Using scan tool, monitor COLUMN LOCK parameters: FUEL DISABLE-BCM DTC, PCM-BCM COM and FUEL DISABLE-ABS DTC. If any of the listed parameters indicate a problem with column lock system, diagnose body control system and/or anti-lock brake system. If no problem is indicated, go to next step.
7. Using scan tool, observe DTC status for MIL REQUEST, FAIL THIS IGN, LAST TEST FAIL and HISTORY. If any DTC is stored, save freeze frame and failure records information using scan tool CAPTURE INFO feature. Diagnose DTCs. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS (PASSENGER CARS)»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If DTCs are not present, go to next step.
8. Compare scan tool engine data with typical control system data values. For scan tool data values, refer to scan tool manufacturer owner's manual. If data values are within limits, see appropriate TROUBLE SHOOTING - NO CODES article in ENGINE PERFORMANCE. If data values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article in ENGINE PERFORMANCE.

Note. Only transmission-related trouble codes are listed. For engine-related DTC definitions, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. These DTCs pertain to engine performance and must be repaired first, as engine performance and related component signals will affect transmission operation and diagnosis.

DIAGNOSTIC TROUBLE CODE DEFINITIONS (PASSENGER CARS)

ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (LIGHT TRUCKS & VANS)

Note. Only transmission-related trouble codes are listed. For engine-related DTC definitions, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. These DTCs pertain to engine performance and must be repaired first, as engine performance and related component signals will affect transmission operation and diagnosis.

Description

The OBD System Check determines

1. If Malfunction Indicator Light (MIL) works.
2. If PCM is operating and can recognize a fault.
3. If any codes are stored.

OBD system check is the starting point for utilizing the self-diagnostic system for determining computer-related problems. Use of scan tool is required to perform OBD system check. Perform this test prior to performing any diagnostic procedures in DTC tests. For scan tool data values, refer to scan tool manufacturer owner's manual. After performing necessary tests as described in diagnostic system check, if no DTCs are indicated and driveability problems still exist, see appropriate TROUBLE SHOOTING - NO CODES article in ENGINE PERFORMANCE.

2.2L

1. Connect scan tool. Turn ignition on, with engine off. If scan tool powers up, go to next step. If scan tool does not power up, go to «NO DATA LINK CONNECTOR (DLC) DATA»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__no-data-link-connector-dlc-data) .
2. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to «NO DATA LINK CONNECTOR (DLC) DATA»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__no-data-link-connector-dlc-data) .
3. Using scan tool, check for DTCs. If any LAST TEST FAIL, HISTORY or MIL request DTCs are present, go to next step. If no DTCs are present, go to step 5 .
4. Using scan tool, record FREEZE FRAME and FAILURE RECORDS information. Identify DTCs. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS (LIGHT TRUCKS & VANS)»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . After identification, diagnose DTCs.
5. Observe MIL. If MIL is illuminated, go to next step. If MIL is not illuminated, go to «NO MALFUNCTION INDICATOR LIGHT (MIL)»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__no-malfunction-indicator-light-mil) .
6. Using scan tool, command MIL off. If MIL turns off, go to next step. If MIL does not turn off, see MIL ON STEADY test in appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
7. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and then stalls, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article in ENGINE PERFORMANCE.
8. Allow engine to idle. During engine warm-up, check ECT, TP, MAP, O2 sensors and IAC valve for proper operation. Compare actual scan tool data with typical scan tool data values. For scan tool data values, refer to scan tool manufacturer owner's manual. If values are within limits, see appropriate TROUBLE SHOOTING - NO CODES article in ENGINE PERFORMANCE. If values are not within limits, go to appropriate SYSTEM & COMPONENT TESTING article in ENGINE PERFORMANCE.

4.3L, 5.0L & 5.7L (VIN R)

1. Connect scan tool. Turn ignition on, with engine off. Observe MIL. If MIL illuminates, go to next step. If MIL does not illuminate, see «NO MALFUNCTION INDICATOR LIGHT (MIL)»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__no-malfunction-indicator-light-mil) .
2. Using scan tool, attempt to communicate with VCM. If scan tool displays VCM data, go to next step. If scan tool does not display VCM data, see «NO DATA LINK CONNECTOR (DLC) DATA»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__no-data-link-connector-dlc-data) .
3. Using scan tool, observe DTC status for MIL REQUEST, FAIL THIS IGN, LAST TEST FAIL and HISTORY. If any DTC is stored, save freeze frame and failure records information using scan tool CAPTURE INFO feature. Diagnose DTCs. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS (LIGHT TRUCKS & VANS)»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If DTCs are not present, go to next step.
4. Using scan tool, monitor SERIAL DATA CLASS II messages. If all other control modules are communicating with scan tool, go to next step. If all other control modules do not communicate with scan tool, see «NO DATA LINK CONNECTOR (DLC) DATA»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__no-data-link-connector-dlc-data) .
5. Attempt to start engine. If engine starts and continues to run, go to step 7 . If engine does not start, or starts and then stalls, go to next step.
6. Using scan tool, check for any Passlock® DTCs. If DTCs are present, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If no DTCs are present, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
7. Using scan tool, command MIL to turn off. If MIL turns off, go to next step. If MIL does not turn off, see «NO MALFUNCTION INDICATOR LIGHT (MIL)»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__no-malfunction-indicator-light-mil) .
8. Compare scan tool engine data with typical control system data values. For scan tool data values, refer to scan tool manufacturer owner's manual. If values are within limits, see appropriate TROUBLE SHOOTING - NO CODES article in ENGINE PERFORMANCE. If values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article in ENGINE PERFORMANCE.

4.8L & 5.3L

1. Connect scan tool. Turn ignition on, with engine off. If scan tool powers up, go to next step. If scan tool does not power up, go to «NO DATA LINK CONNECTOR (DLC) DATA»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__no-data-link-connector-dlc-data) .
2. If scan tool displays PCM data, go to step 4 . If scan tool does not display PCM data, go to next step.
3. Using scan tool, select DIAGNOSTIC CIRCUIT CHECK and CLASS 2 MESSAGE MONITOR. If scan tool displays any other modules as ACTIVE, go to «NO DATA LINK CONNECTOR (DLC) DATA»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__no-data-link-connector-dlc-data) . If scan tool does not display any other modules as ACTIVE, check scan tool connection. Check circuits between DLC and control module which does not communicate with scan tool. See appropriate wiring diagram in WIRING DIAGRAMS article in ENGINE PERFORMANCE. Repair as necessary.
4. Using scan tool, monitor IGNITION 1 voltage while cranking engine. If voltage is near battery voltage, go to next step. If voltage is not as specified, diagnose system using appropriate test for DTC P0562. See DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
5. If engine starts and continues to run, go to step 8 . If engine does not start, or starts and then stalls, go to next step.
6. If any PCM, BCM or VTD DTCs related to vehicle theft deterrent system are present, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If no DTCs are present, go to next step.
7. Using scan tool in BODY mode, monitor PCM/VCM FUEL CONTINUE parameter while cranking engine. If scan tool displays FUEL CONTINUE as NO, diagnose theft deterrent system. See appropriate ANTI-THEFT SYSTEMS article in ACCESSORIES & EQUIPMENT. If scan tool does not display FUEL CONTINUE as NO, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article in ENGINE PERFORMANCE.
8. Using scan tool, capture DTC FREEZE FRAME and/or FAILURE RECORDS information. Monitor DTC information. If DTCs are present, diagnose DTCs. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS (LIGHT TRUCKS & VANS)»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If DTCs are not present, go to next step.
9. Compare scan tool engine data with typical control system data values. For scan tool data values, refer to scan tool manufacturer owner's manual. If data values are within limits, see appropriate TROUBLE SHOOTING - NO CODES article in ENGINE PERFORMANCE. If data values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article in ENGINE PERFORMANCE.

DIAGNOSTIC TROUBLE CODE DEFINITIONS (LIGHT TRUCKS & VANS)

HARD OR INTERMITTENT TROUBLE CODE DETERMINATION

Note. DTCs will be recorded at various operating times. Some DTCs require operation of that sensor or switch for 5 seconds; others require operation for 5 minutes or longer at normal operating temperature, vehicle speed and load. Therefore, some DTCs may not set in a service bay operational mode and may require road testing vehicle in order to duplicate conditions under which code will set.

During any diagnostic procedure, determine if DTC(s) are hard failure codes or intermittent failure codes. Diagnostic procedures will not always help analyze intermittent codes. To determine hard codes and intermittent codes

1. Enter diagnostic mode. Read and record all stored DTCs. Exit diagnostic mode and clear DTCs. See «CLEARING TROUBLE CODES»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__clearing-trouble-codes) .
2. Apply parking brake and place transmission in Neutral or Park. Block drive wheels and start engine. MIL should turn off. Allow engine to reach normal operating temperature and continue to run for 2 minutes and note MIL.
3. If MIL illuminates, enter diagnostic mode. Read and record DTCs. This will reveal hard failure codes. Oxygen sensor related DTCs may require a road test to reset hard failures after DTCs were cleared. If MIL does not illuminate, all stored DTCs were intermittent failures.

CLEARING TROUBLE CODES

DTCs can be cleared using scan tool. If scan tool is not available, turn ignition switch to OFF position. Remove control module fuse from fuse block for 30 seconds. Replace fuse. If fuse cannot be located, disconnect PCM/VCM pigtail at battery for 30 seconds. Codes may also be cleared by disconnecting negative battery cable. However, this may result in loss of other on-board memory data, such as preset radio tuning. After power to PCM/VCM is removed, poor driveability may occur until control module "relearns" operating parameters.

DTCs will also be cleared under the following conditions: PCM/VCM will turn off MIL after 3 consecutive ignition cycles without a failure reported. PCM/VCM will cancel DTC default actions when fault no longer exists and ignition is cycled off long enough to power down PCM/VCM. DTC will be cleared when vehicle has achieved 40 warm-up cycles without a failure reported.

CONNECTOR IDENTIFICATION

Note. For connector identification, refer to illustrations. (Scheme 11)- (Scheme 13).

Scheme 11

Scheme 12

Scheme 13

DIAGNOSTIC TESTS (PASSENGER CARS)

Note. Not all DTCs are applicable to all models.

Diagnostic Tests

The following diagnostic tests are DTC specific. Always perform On-Board Diagnostic (OBD) System Check prior to performing any diagnostic procedure. For PCM terminal locations (Scheme 12)and WIRING DIAGRAMS. For engine-related DTCs, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.

Diagnostic aids, located at end of each diagnostic test, are additional tips used to help diagnose trouble codes when diagnostic procedures do not find a problem.

Wiring Diagrams

PCM connector colors and terminal identification may vary with vehicle model and engine size. When using diagnostic tests, see appropriate wiring diagram to determine which PCM connector(s) to disconnect during test procedure. Locate component being tested and trace specified wiring circuit to determine PCM connector and terminal related to that component.

DTC P0218: TRANSMISSION FLUID OVERTEMP.

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS . Transmission Fluid Pressure (TFP) manual valve position switch assembly may also be referred to as Pressure Switch Assembly (PSA).

Flow of transmission fluid starts in bottom pan and is drawn through filter, control valve body, transmission case and into oil pump assembly. Oil pump assembly pressurizes fluid and directs it to pressure regulator valve, where it becomes the main supply of fluid to various components and hydraulic circuits in transmission. Hot fluid exiting torque converter flows through converter clutch apply valve and into transmission cooler lines to oil cooler and auxiliary cooler, if equipped. From cooler, fluid returns to cool and lubricate front of transmission. In forward drive ranges, "D4" fluid from manual valve is routed through an orificed cup plug in rear of transmission case to feed rear lube fluid circuit. DTC P0218 is set if PCM detects a high transmission fluid temperature for long periods of time.

Conditions For Setting DTC P0218

DTC will set under the following conditions

1. DTCs P0711, P0712 or P0713 (TFT sensor) are not present.
2. Transmission fluid temperature is more than 266°F (130°C).

Action Taken By PCM

PCM performs the following if DTC is set

1. Will not illuminate MIL when fault is set.
2. Freezes shift adapts from being updated.
3. DTC P0218 will be stored in PCM history.

1. Ensure fluid level is correct. Fill as needed. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. If DTC P0711 is also set, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If DTC P0711 is not set, inspect engine and transmission cooling system for restrictions, blockage or debris. Check transmission cooler lines for damage. Repair as necessary, then go to next step. If components are okay, perform line pressure test. See LINE PRESSURE TESTS in HYDRA-MATIC 4L60-E OVERHAUL article. If line pressure is within specification, go to next step. If line pressure is not within specification, check torque converter stator for damage. See TORQUE CONVERTER in HYDRA-MATIC 4L60-E OVERHAUL article.
3. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Select Specific DTC and enter DTC "P0218". Turn ignition switch to ON position. Scan tool must indicate fluid temperature less than 264°F (129°C) for at least 5 seconds. If DTC P0218 is not present, repair is complete. If DTC P0218 is still present, repeat test.

DTC P0218 may set 10 minutes after DTC P0711 has set. If DTC P0711 has set, repair before proceeding with DTC P0218. DTC P0218 will most likely eliminated once DTC P0711 is repaired.

TFT displayed on scan tool should rise steadily to normal operating temperature, then stabilize. Verify driver habits such as towing trailer in "D4". Towing should be performed in "D3".

DTC P0502: VEHICLE SPEED SENSOR CIRCUIT (LOW INPUT)

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Vehicle speed is signaled to PCM by Vehicle Speed Sensor (VSS). Sensor is a Permanent Magnet (PM) generator mounted to transmission case extension. PM generator produces an AC voltage as speed sensor rotor teeth pass sensor's magnetic field. PCM converts AC voltage into digital signal. PCM uses vehicle speed to determine shift timing and TCC apply and release. VSS voltage will vary from a minimum of .5 volt AC at 100 RPM to more than 100 volts AC at 8000 RPM. DTC P0502 is set if PCM detects a low vehicle output speed when vehicle has high engine speed in drive gear.

Conditions For Setting DTC P0502

DTC will set under the following conditions

1. Transmission is not in Park or Neutral.
2. DTCs P0107 and P0108 (MAP sensor), or P0122 and P0123 (throttle position sensor) are not present.
3. DTC P1810 (TFP manual valve position switch) is not present.
4. Engine speed is 3000-4800 RPM.
5. Throttle angle is more than 15 percent.
6. Engine speed is more than 3000 RPM.
7. Output speed is less than 150 RPM for 3 seconds.

PCM performs the following if DTC is set

1. Will illuminate MIL at first failure signal.
2. Commands 2nd gear only (3.8L).
3. Commands 1st gear only (5.7L).
4. Inhibits TCC engagement.
5. Freezes shift adapts from being updated.
6. Commands maximum line pressure.
7. DTC P0502 will be stored in PCM history.

Note. If PCM replacement is necessary, ensure new PCM is reprogrammed. See COMPUTER RELEARN PROCEDURES article in APPLICATIONS & IDENTIFICATION.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Select DTC on scan tool. Select "CLEAR INFO" function.
2. Raise and support vehicle. Start engine and let idle. Disable traction control system (if equipped). Shift gear selector to any forward position. Select "Output Speed" on scan tool. Allow drive wheels to rotate. If transmission output speed does not increase when wheel speed increases, go to next step. If transmission output speed increases when wheel speed increases, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
3. Turn ignition off. Disconnect appropriate PCM connector connected to VSS. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . Using an ohmmeter, measure resistance between VSS terminals at appropriate PCM connector. If resistance is 1377-3355 ohms (Camaro and Firebird) or 976-2354 (Corvette), go to next step. If resistance is not as specified, go to step 6 .
4. Measure resistance between ground and VSS High terminal on appropriate PCM harness connector. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If resistance is greater that 50 k/ohms, go to next step. If resistance is not as specified, go to step 7 .
5. Connect voltmeter between VSS terminals at appropriate PCM connector terminals. Rotate drive wheels (ensure driveshaft is turning) and observe voltmeter display. If voltage is less than .5 volt, go to step 8 . If voltage is more than .5 volt, go to step 9 .
6. Disconnect VSS connector. Measure resistance between VSS component terminals. If resistance is 1377-3355 ohms (Camaro and Firebird) or 976-2354 (Corvette) ohms, go to next step. If resistance is not as specified, replace VSS. Go to step 10 .
7. Inspect VSS High and Lo circuits between VSS connector and appropriate PCM harness connector for open or short to ground. Repair as needed. Go to step 10 . If both circuits are okay, go to «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
8. Remove VSS from transmission. Inspect output speed sensor rotor for damage or misalignment. Repair as necessary, then go to next step. If rotor is okay, replace VSS, then go to next step.
9. Check PCM connector for damaged or backed out connector terminals, weak terminal tension and poor connections. Repair as necessary, then go to next step. If terminals and connections are okay, replace PCM. Ensure PCM is reprogrammed. Go to next step.
10. After repair is complete, select DTC on scan tool. Select "CLEAR INFO" function. Select "Specific DTC" and enter DTC "P0502". Test drive vehicle. Ensure transmission output speed is more than 251 RPM for 2 seconds. If DTC P0502 is not present, repair is complete. If DTC P0502 is still present, repeat test.

DTC P0502 sets when no vehicle speed is detected at start-off. Check for Electromagnetic Interferences (EMI) induced on VSS circuits caused by misrouted wiring harness too near spark plug wires. Check wiring for poor connections at PCM connector and transmission 20-pin connector. Check for bent, backed out or broken terminals, or misaligned connectors. Inspect for damaged VSS or for damaged output speed sensor rotor teeth. Check for moisture and corrosion. Ensure VSS is aligned correctly and secured to transmission case properly. An incorrect calibration may set DTC P0502. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0503: VEHICLE SPEED SENSOR CIRCUIT (INTERMITTENT)

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Vehicle speed is signaled to PCM by Vehicle Speed Sensor (VSS). Sensor is a Permanent Magnet (PM) generator mounted to transmission case extension. PM generator produces an AC voltage as speed sensor rotor teeth pass sensor's magnetic field. PCM converts AC voltage into digital signal. PCM uses vehicle speed to determine shift timing, TCC apply and release, and gear ratio calculations. VSS voltage will vary from .5 volt AC at 100 RPM to more than 100 volts AC at 8000 RPM. DTC P0503 is set if PCM detects a large drop in vehicle speed.

Conditions For Setting DTC P0503

DTC will set under the following conditions

1. Transmission is not in Park, Neutral or Reverse.
2. DTC P1810 (TFP manual valve position switch) is not present.
3. Engine is not in fuel shut off mode.
4. Time since last gear range change is more than 6 seconds.
5. Engine speed is more than 450 RPM.
6. Transmission output speed does not rise by 500 RPM within 6 seconds.
7. Transmission output speed drops by more than 1300 RPM for 3 seconds and is not in Park or Neutral.
8. Transmission output speed drops by more than 1600 RPM for 3 seconds in Park or Neutral.
9. All conditions are met for 3 seconds.

PCM performs the following if DTC is set

1. Will illuminate MIL when fault is set.
2. Inhibits TCC engagement.
3. Commands maximum line pressure.
4. Commands a soft shift to 2nd gear.
5. Inhibits 4th gear in hot mode.
6. Freezes shift adapts from being updated.
7. DTC P0503 will be stored in PCM history.

Note. If PCM replacement is necessary, ensure new PCM is reprogrammed. See COMPUTER RELEARN PROCEDURES article in APPLICATIONS & IDENTIFICATION.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Select DTC on scan tool. Select CLEAR INFO function.
2. Raise and support vehicle. Start engine and let idle. Disable traction control system (if equipped). Shift gear selector to D3 position. Select "Output Speed" on scan tool. Allow drive wheels to rotate. Slowly accelerate until engine reaches 2000 RPM and hold speed. Transmission output speed should be about 1300 RPM. If output speed is maintained as specified, go to next step. If transmission output speed fluctuates above or below 1300 RPM, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
3. Turn ignition off. Disconnect appropriate PCM connector connected to VSS. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . Using an ohmmeter, measure resistance between VSS terminals at appropriate PCM connector. If resistance is 1377-3355 ohms (Camaro and Firebird) or 976-2354 (Corvette), go to next step. If resistance is not as specified, go to step 6 .
4. Measure resistance between ground and VSS High terminal on appropriate PCM harness connector. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If resistance is greater that 50 k/ohms, go to next step. If resistance is not as specified, go to step 7 .
5. Connect voltmeter between VSS terminals at appropriate PCM connector terminals. Rotate drive wheels (ensure driveshaft is turning) and observe voltmeter display. If voltage is less than .5 volt, go to step 8 . If voltage is more than .5 volt, go to step 9 .
6. Disconnect VSS connector. Measure resistance between VSS component terminals. If resistance is 1377-3355 ohms (Camaro and Firebird) or 976-2354 (Corvette) ohms, go to next step. If resistance is not as specified, replace VSS. Go to step 10 .
7. Inspect VSS High and Lo circuits between VSS connector and appropriate PCM harness connector for open or short to ground. Repair as needed. Go to step 10 . If both circuits are okay, go to «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
8. Remove VSS from transmission. Inspect output speed sensor rotor for damage or misalignment. Repair as necessary, then go to next step. If rotor is okay, replace VSS, then go to next step.
9. Check PCM connector for damaged or backed out connector terminals, weak terminal tension and poor connections. Repair as necessary, then go to next step. If terminals and connections are okay, replace PCM. Ensure PCM is reprogrammed. Go to next step.
10. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Select Specific DTC and enter DTC "P0503". Test drive vehicle. Ensure transmission output speed is more than 600 RPM for 3 seconds. If DTC P0503 is not present, repair is complete. If DTC P0503 is still present, repeat test.

An incorrect VSS calibration may set DTC P0503. Check for Electromagnetic Interference (EMI) induced on VSS circuits caused by misrouted wires along spark plug wires. Ensure VSS is secured to transmission case extension an correctly aligned. Check for damaged VSS or rotor teeth. Inspect wiring for poor connections at PCM and at transmission 20-pin connector. Check for bent, backed out or broken terminals or misaligned connectors. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0711: TRANSMISSION FLUID TEMPERATURE (TFT) SENSOR CIRCUIT (RANGE/PERFORMANCE)

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Transmission Fluid Temperature (TFT) sensor is a negative coefficient thermistor within TFP manual valve position switch. TFT sensor controls signal voltage from PCM. PCM supplies a 5-volt reference signal to sensor. When transmission fluid temperature is cold, sensor resistance is high, and PCM detects high signal voltage. As transmission fluid temperature increases, sensor resistance decreases and detected voltage decreases. At transmission normal operating temperature of 212°F (100°C), voltage is about 1.5-2 volts. TFT sensor resistance is 159-198 ohms. DTC P0711 is set if PCM detects a large change in transmission fluid temperature or if PCM detects a TFT value which remains constant for a period of time in which a measurable amount of change is expected for 2 consecutive ignition cycles.

Conditions For Setting DTC P0711

DTC will set under the following conditions

1. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
2. System voltage is 10-16 volts.
3. Transmission fluid temperature sensor voltage is .2-4.92 volts.
4. Transmission fluid temperature at start-up is -40 to 70 °F (-40 to 21°C).
5. DTC P1870 (transmission component slipping) is not present.
6. Engine is running for more than 7 minutes.
7. Vehicle speed is equal to or more than 5 MPH for 7 minutes or more within a single ignition cycle.
8. Transmission fluid temperature is equal to or more than 158°F (70°C) and has changed by at least 90°F (50°C) since start-up.
9. TCC slip speed is equal to or more than 120 RPM for 7 minutes or more within a single ignition cycle.
10. All of the above conditions are met and either of the following failure criteria occur in 2 consecutive ignition cycles

Failure Criteria (Case No. 1)

Transmission fluid temperature has changed by less than 2.7°F (1.5°C) since start-up and condition is met for 7 minutes or more.

Failure Criteria (Case No. 2)

Transmission fluid temperature has changed by more than 36°F (20°C) within .2 seconds, and condition is met 14 times or more within 7 seconds.

PCM performs the following if DTC is set

1. Will not illuminate MIL.
2. Freezes shift adapts from being updated.
3. DTC P0711 is stored in PCM history.
4. Determines a default transmission fluid temperature using the following information

Default Temperatures

If any ECT DTC (P0117, P0118, P1114 or P1115) is set, PCM substitutes a transmission fluid temperature default value of 275°F (135°C). If ECT is more than 257°F (125 °C), PCM substitutes a transmission fluid temperature value of 275°F (135°C).

If engine run time is less than 5 minutes, and no IAT DTCs (P0112 or P0113) are set and IAT is available, PCM substitutes a transmission fluid temperature value equal to IAT.

If any IAT DTCs (P0112 or P0113) are set, or IAT is not available, PCM substitutes a transmission fluid temperature default value of 194°F (90°C).

If engine run time is more than 5 minutes, no IAT DTCs (P0112 or P0113) are set, IAT is available, ECT is 104-257°F (40-125°C), and IAT at start-up is less than 59°F (15°C), PCM substitutes a transmission fluid temperature default value equal to ECT plus 8°F (5°C). If IAT at start-up is more than 95°F (35°C), PCM substitutes a transmission fluid temperature default value equal to ECT plus 16°F (10°C). If IAT at start-up is 59-95°F (15-35°C), PCM substitutes a transmission fluid temperature default value equal to ECT.

If engine run time is more than 5 minutes, and any IAT DTCs (P0112 or P0113) is set, or IAT is not available, PCM substitutes a transmission fluid temperature default value equal to ECT.

If engine run time is more than 5 minutes, and ECT is less than 104°F (40°C), PCM substitutes a transmission fluid temperature default value equal to 140°F (60°C).

Note. If PCM replacement is necessary, ensure new PCM is reprogrammed. See COMPUTER RELEARN PROCEDURES article in APPLICATIONS & IDENTIFICATION.

1. Ensure transmission fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "TFT" on scan tool. Drive vehicle and observe scan tool for either of the following fail conditions: TFT does not change more than 2.7°F (1.5°C) in 7 minutes since start-up, or TFT changes more than 36°F (20°C) in.200 seconds, 14 times within 7 seconds (out of range change). If either of these conditions occurred, go to next step. If neither of these conditions occurred, cause is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e).
3. If scan tool displays a condition in which TFT does not change by more than 2.7°F (1.5°C) in 7 minutes since start-up, go to step 5. If scan tool does not display a condition in which TFT does not change by more than 2.7°F (1.5°C) in 7 minutes since start-up, go to next step.
4. Turn ignition off. Disconnect transmission 20-pin connector. Install Jumper Harness (J-39775) on engine side of transmission 20-pin connector. Connect test light between terminals "L" and "M". (Scheme 10) Turn ignition switch to ON position. Do not start engine. While observing scan tool, wiggle engine wiring harness from appropriate PCM connector to transmission 20-pin connector. If TFT temperature changes by more than 36°F (20°C), go to step 6. If TFT temperature does not change by more than 36°F (20°C), go to step 7.
5. Turn ignition off. Disconnect transmission 20-pin connector. Turn ignition switch to ON position. Do not start engine. If scan tool displays a condition in which TFT does not change by more than 2.7°F (1.5°C) in 7 minutes since start-up, replace PCM. Ensure PCM is reprogrammed. Go to step 8. If scan tool does not display a condition in which TFT does not change by more than 2.7°F (1.5°C) in 7 minutes since start-up, replace TFT sensor, then go to step 8.
6. Check for intermittent open or short condition in TFT sensor circuits between PCM connector and transmission 20-pin connector. Repair circuit(s) as necessary, then go to step 8. If circuits are okay, replace PCM. Ensure PCM is reprogrammed. Go to step 8.
7. Check for intermittent open or short condition in TFT sensor circuits between transmission 20-pin connector and TFT sensor. Repair circuit(s) as necessary, then go to next step. If circuits are okay, replace TFT sensor, then go to next step.
8. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Select Specific DTC and enter DTC "P0711". Road test vehicle. Monitor transmission fluid temperature. Ensure that rise in fluid temperature is more than 4°F (2.25°C) within 11 seconds since start-up, and fluid temperature does not change by more than 36°F (20°C) within.200 seconds for a period of at least 11 seconds. If DTC P0711 is not present, repair is complete. If DTC P0711 is still present, repeat test.

If DTC P0218 (transmission fluid overtemp.) is also set, inspect transmission cooling system for blockage and restrictions. DTC P0218 may set about 10 minutes after DTC P0711 has set. If DTC P0711 is also set, perform diagnostic procedure for that DTC before diagnosing DTC P0218. Repairing condition that caused DTC P0711 will probably eliminate DTC P0218. Verify driver habits such as towing trailer in "D4". Towing should be performed in "D3". Inspect wiring for poor connections at PCM and at transmission 20-pin connector. Check for bent, backed out or broken terminals, or misaligned connectors. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. Check for moisture and corrosion. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0712: TRANS. FLUID TEMPERATURE (TFT) SENSOR CIRCUIT (LOW INPUT)

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Transmission Fluid Temperature (TFT) sensor is a negative coefficient thermistor within Transmission Fluid Pressure (TFP) manual valve position switch. TFP is also referred to as Pressure Switch Assembly (PSA). TFT sensor controls signal voltage from PCM. PCM provides a 5-volt reference to sensor on TFT sensor signal circuit. When transmission fluid is cold, sensor resistance is high, and PCM detects high signal voltage. As transmission fluid temperature increases, sensor resistance decreases and voltage decreases. At normal operating temperature of 212°F (100°C), voltage is about 1.5-2 volts. Check sensor for shifted calibration by using sensor TEMPERATURE-TO-RESISTANCE VALUES table. DTC P0712 is set if PCM detects a continuous short to ground in TFT sensor signal circuit or TFT sensor.

Conditions For Setting DTC P0712

DTC will set under the following conditions

1. System voltage is 10-16 volts.
2. Ignition switch is in ON position.
3. TFT sensor indicates a voltage less than .2 volt.
4. All conditions are met for 10 seconds.

PCM performs the following if DTC is set

1. Will illuminate MIL after 2 consecutive trips with failure.
2. Defaults transmission temperature to 275°F (135°C).
3. Freezes shift adapts from being updated.
4. Determines a default transmission fluid temperature using the following information

If any ECT DTC (P0117, P0118, P1114 or P1115) is set, PCM substitutes a transmission fluid temperature default value of 275°F (135°C). If ECT is more than 257°F (125 °C), PCM substitutes a transmission fluid temperature value of 275°F (135°C).

If engine run time is less than 5 minutes, and no IAT DTCs (P0112 or P0113) are set and IAT is available, PCM substitutes a transmission fluid temperature value equal to IAT.

If any IAT DTCs (P0112 or P0113) are set, or IAT is not available, PCM substitutes a transmission fluid temperature default value of 194°F (90°C).

If engine run time is more than 5 minutes, no IAT DTCs (P0112 or P0113) are set, IAT is available, ECT is 104-257°F (40-125°C), and IAT at start-up is less than 59°F (15°C), PCM substitutes a transmission fluid temperature default value equal to ECT plus 8°F (5°C). If IAT at start-up is more than 95°F (35°C), PCM substitutes a transmission fluid temperature default value equal to ECT plus 16°F (10°C). If IAT at start-up is 59-95°F (15-35°C), PCM substitutes a transmission fluid temperature default value equal to ECT.

If engine run time is more than 5 minutes, and any IAT DTCs (P0112 or P0113) is set, or IAT is not available, PCM substitutes a transmission fluid temperature default value equal to ECT.

If engine run time is more than 5 minutes, and ECT is less than 104°F (40°C), PCM substitutes a transmission fluid temperature default value equal to 140°F (60°C).

Note. If PCM replacement is necessary, ensure new PCM is reprogrammed. See COMPUTER RELEARN PROCEDURES article in APPLICATIONS & IDENTIFICATION.

1. Ensure transmission fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Read TFT sensor signal voltage on scan tool. If TFT sensor signal voltage is less than .2 volt, go to next step. If TFT sensor signal voltage is more than .2 volt, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
3. Turn ignition off. Disconnect transmission 20-pin connector. Turn ignition switch to ON position. Do not start engine. If TFT sensor signal voltage is 4.92 volts, go to next step. If TFT sensor signal voltage is not 4.92 volts, check for short to ground in TFT sensor signal circuit. Repair circuit as necessary, then go to step 7 . If circuit is okay, go to step 6 .
4. Install Jumper Harness (J-39775) on transmission side of 20-pin connector. Using a DVOM, measure resistance of TFT sensor between TFP manual valve position switch terminals of jumper harness. If resistance is 3088-3942 ohms at 68° F (20° C), see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
5. If resistance is not 3088-3942 ohms at 68° F (20° C), remove transmission oil pan. Check for short to ground in transmission wiring harness. Repair as necessary. If wiring harness is okay, disconnect TFT sensor connector. Measure resistance between TFT sensor terminals. If resistance is 3088-3942 ohms at 68° F (20° C), see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If resistance is not 3088-3942 ohms at 68° F (20° C), replace TFP manual valve position switch, then go to step 7 .
6. Check PCM connector for damaged or backed out connector terminals, weak terminal tension and poor connections. Repair as necessary, then go to next step. If terminals and connections are okay, replace PCM. Ensure PCM is reprogrammed. Go to next step.
7. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Select Specific DTC and enter DTC "P0712". Ensure TFT sensor indicates a voltage more than .2 volt for 10 seconds. If DTC P0712 is not present, repair is complete. If DTC P0712 is still present, repeat test.

Inspect wiring for poor connections at PCM and at transmission 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change. If DTC P0218 is also set, check transmission cooling system for possible blockage and/or restrictions.

TEMPERATURE-TO-RESISTANCE VALUES (1)

DTC P0713: TRANS. FLUID TEMPERATURE (TFT) SENSOR CIRCUIT (HIGH INPUT)

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Transmission Fluid Temperature (TFT) sensor is a negative coefficient thermistor within Transmission Fluid Pressure (TFP) manual valve position switch. TFT sensor controls signal voltage from PCM. PCM provides a 5-volt reference to sensor on TFT sensor signal circuit. When transmission fluid is cold, sensor resistance is high, and PCM detects high signal voltage. As transmission fluid temperature increases, sensor resistance decreases and voltage decreases. At normal operating temperature of 212°F (100°C), voltage is about 1.5-2 volts. Check sensor for shifted calibration by using sensor TEMPERATURE-TO-RESISTANCE VALUES table. DTC P0713 is set if PCM detects a continuous open or short to voltage in TFT sensor signal circuit or TFT sensor.

Conditions For Setting DTC P0713

DTC will set under the following conditions

1. System voltage is 10-16 volts.
2. Ignition switch is in ON position.
3. TFT sensor indicates a voltage less than 4.94 volts.
4. All conditions are met for 7 minutes.

PCM performs the following if DTC is set

1. Will illuminate MIL after 2 consecutive trips with failure.
2. Defaults transmission temperature to 275°F (135°C).
3. Freezes shift adapts from being updated.
4. Determines a default transmission fluid temperature using the following information

If any ECT DTC (P0117, P0118, P1114 or P1115) is set, PCM substitutes a transmission fluid temperature default value of 275°F (135°C). If ECT is more than 257°F (125 °C), PCM substitutes a transmission fluid temperature value of 275°F (135°C).

If engine run time is less than 5 minutes, and no IAT DTCs (P0112 or P0113) are set and IAT is available, PCM substitutes a transmission fluid temperature value equal to IAT.

If any IAT DTCs (P0112 or P0113) are set, or IAT is not available, PCM substitutes a transmission fluid temperature default value of 194°F (90°C).

If engine run time is more than 5 minutes, no IAT DTCs (P0112 or P0113) are set, IAT is available, ECT is 104-257°F (40-125°C), and IAT at start-up is less than 59°F (15°C), PCM substitutes a transmission fluid temperature default value equal to ECT plus 8°F (5°C). If IAT at start-up is more than 95°F (35°C), PCM substitutes a transmission fluid temperature default value equal to ECT plus 16°F (10°C). If IAT at start-up is 59-95°F (15-35°C), PCM substitutes a transmission fluid temperature default value equal to ECT.

If engine run time is more than 5 minutes, and any IAT DTCs (P0112 or P0113) is set, or IAT is not available, PCM substitutes a transmission fluid temperature default value equal to ECT.

If engine run time is more than 5 minutes, and ECT is less than 104°F (40°C), PCM substitutes a transmission fluid temperature default value equal to 140°F (60°C).

Note. If PCM replacement is necessary, ensure new PCM is reprogrammed. See COMPUTER RELEARN PROCEDURES article in APPLICATIONS & IDENTIFICATION.

1. Ensure transmission fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Read TFT sensor signal voltage on scan tool. If TFT sensor signal voltage is more than 4.92 volts, go to next step. If TFT sensor signal voltage is less than 4.92 volts, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
3. Turn ignition off. Disconnect transmission 20-pin connector. Install Jumper Harness (J-39775) on engine side of transmission 20-pin connector. Install fused jumper wire between appropriate PCM connector TFT sensor ground terminal, and appropriate PCM connector TFT sensor signal terminal of jumper harness. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . Turn ignition switch to ON position. Do not start engine. If TFT sensor signal voltage is less than .2 volt, go to next step. If TFT sensor signal voltage is more than .2 volt, check for open or short to voltage in TFT sensor signal circuit, or for open in TFT ground circuit. Repair circuits as necessary, then go to step 7 . If circuits are okay, go to step 6 .
4. Turn ignition off. Remove jumper wire. Disconnect jumper harness from engine side of 20-pin connector. Install jumper harness on transmission side of 20-pin connector. Using a DVOM, measure resistance of TFT sensor harness between TFP manual valve position switch terminals of jumper harness. If resistance is 3088-3942 ohms at 68° F (20° C), see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
5. If resistance is not 3088-3942 ohms at 68° F (20° C), remove transmission oil pan. Check for open in transmission wiring harness. Repair as necessary, then go to step 7 . If wiring harness is okay, disconnect TFT sensor connector. Measure resistance between TFT sensor terminals. If resistance is 3088-3942 ohms at 68° F (20° C), see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If resistance is not 3088-3942 ohms at 68° F (20° C), replace TFP manual valve position switch, then go to step 7 .
6. Check PCM connector for damaged or backed out connector terminals, weak terminal tension and poor connections. Repair as necessary, then go to next step. If terminals and connections are okay, replace PCM. Ensure PCM is reprogrammed. Go to next step.
7. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Select Specific DTC and enter DTC "P0713". Ensure TFT sensor indicates a voltage less than 4.92 volts for 2 seconds. If DTC P0713 is not present, repair is complete. If DTC P0713 is still present, repeat test.

Inspect wiring for poor connections at PCM and at transmission 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change. Check engine and transmission harness for open condition.

DTC P0719: BRAKE SWITCH CIRCUIT LOW INPUT (SWITCH STUCK ON)

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Torque Converter Clutch (TCC) brake switch is used to indicate brake pedal status to PCM. PCM de-energizes TCC solenoid when brake pedal is applied. DTC P0719 is set if PCM detects an open (stuck on) brake switch during acceleration.

Conditions For Setting DTC P0719

DTC will set under the following conditions

1. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
2. Vehicle speed is less than 5 MPH.
3. Then vehicle speed is 5-20 MPH for 4 seconds, then vehicle speed is more than 20 MPH for 6 seconds.
4. All conditions must occur 7 times with brake switch on for more than 15 minutes without PCM detecting voltage input of 2 seconds or more.

PCM performs the following if DTC is set

1. Ensures TCC brake switch remains closed with brake pedal released.
2. Inhibits TCC engagement.
3. Inhibits 4th gear if in hot mode.
4. Freezes shift adapts from being updated.
5. DTC P0719 is stored in PCM history.

Note. If PCM replacement is necessary, ensure new PCM is reprogrammed. See COMPUTER RELEARN PROCEDURES article in APPLICATIONS & IDENTIFICATION.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Apply and release brake pedal while observing scan tool. If scan tool displays brake pedal in correct positions, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If scan tool does not display brake pedal in correct positions, go to next step.
3. Connect test light between ground and ignition feed circuit terminal at brake switch. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If test light is off, repair open in ignition feed circuit, then go to step 9 . If test light is on, connect test light between ground and brake switch signal terminal at brake switch. If test light is off, go to step 5 . If test light is on, go to next step.
4. Apply brake pedal. If test light is off, go to step 6 . If test light is on, check brake switch signal circuit for short to voltage. Repair circuit as necessary, then go to step 9 . If circuit is okay, go to next step.
5. Ensure brake switch assembly is adjusted properly. Adjust brake switch as necessary, then go to step 9 . If adjustment is okay, replace brake switch, then go to step 9 .
6. Release brake pedal. Turn ignition off. Disconnect appropriate PCM connector connected to brake switch signal circuit. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . Turn ignition switch to ON position. Do not start engine. Connect test light between ground and brake switch signal terminal of appropriate PCM connector. If test light is on, go to next step. If test light is off, check for open in brake switch signal circuit between brake switch and PCM. Repair as necessary, then go to step 9 .
7. Turn ignition off. Reconnect appropriate PCM connector. Turn ignition switch to ON position. Do not start engine. Apply and release brake pedal. If scan tool displays brake pedal in correct positions, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If scan tool does not display brake pedal in correct positions, go to next step.
8. Check PCM connector for damaged or backed out connector terminals, weak terminal tension and poor connections. Repair as necessary, then go to next step. If terminals and connections are okay, replace PCM. Ensure PCM is reprogrammed. Go to next step.
9. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Select Specific DTC and enter DTC "P0719". Ensure TCC brake switch signal indicates zero volts for 2 seconds with brake pedal applied. If DTC P0719 is not present, repair is complete. If DTC P0719 is still present, repeat test.

Check TCC brake switch for proper adjustment. Check PCM calibration for current update. Inspect wiring for poor connections at PCM. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0724: BRAKE SWITCH CIRCUIT HIGH INPUT (SWITCH STUCK OFF)

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Torque Converter Clutch (TCC) brake switch is used to indicate brake pedal status to PCM. PCM de-energizes TCC solenoid when brake pedal is applied. DTC P0724 is set if PCM detects a closed (stuck off) brake switch during deceleration.

Conditions For Setting DTC P0724

DTC will set under the following conditions

1. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
2. PCM detects a closed TCC brake switch for 2 seconds and the following events occur 7 consecutive times
3. Vehicle speed is more than 20 MPH for 6 seconds.
4. Then vehicle speed is 5-20 MPH for 4 seconds, then vehicle speed is less than 5 MPH.

PCM performs the following if DTC is set

1. Will not illuminate MIL when fault is set.
2. Freezes shift adapts from being updated.
3. DTC P0724 will be stored in PCM history.

Note. If PCM replacement is necessary, ensure new PCM is reprogrammed. See COMPUTER RELEARN PROCEDURES article in APPLICATIONS & IDENTIFICATION.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Apply and release brake pedal while observing scan tool. If scan tool displays brake pedal in correct positions, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If scan tool does not display brake pedal in correct positions, go to next step.
3. Connect test light between ground and ignition feed circuit terminal at brake switch. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If test light is off, repair open in ignition feed circuit, then go to step 8 . If test light is on, connect test light between ground and brake switch signal terminal at brake switch. If test light is off, go to step 5 . If test light is on, go to next step.
4. Apply brake pedal. If test light is off, go to step 6 . If test light is on, check brake switch signal circuit for short to voltage. Repair circuit as necessary, then go to step 8 . If circuit is okay, go to next step.
5. Ensure brake switch assembly is adjusted properly. Adjust brake switch as necessary, then go to step 8 . If adjustment is okay, replace brake switch, then go to step 8 .
6. Apply and release brake pedal. If scan tool displays brake pedal in correct positions, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If scan tool does not display brake pedal in correct positions, go to next step.
7. Check PCM connector for damaged or backed out connector terminals, weak terminal tension and poor connections. Repair as necessary, then go to next step. If terminals and connections are okay, replace PCM. Ensure PCM is reprogrammed. Go to next step.
8. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Select Specific DTC and enter DTC "P0724". Ensure TCC brake switch signal indicates 12 volts for 2 seconds with brake pedal released. If DTC P0724 is not present, repair is complete. If DTC P0724 is still present, repeat test.

Check TCC brake switch for proper adjustment. Check PCM calibration for current update. Inspect wiring for poor connections at PCM. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for moisture and corrosion. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0740: TCC SOLENOID ELECTRICAL MALFUNCTION

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

In conjunction with TCC PWM solenoid, TCC solenoid is used to control fluid flow acting on TCC valve. TCC valve controls apply and release of TCC. Solenoid is a normally-open on/off device. Solenoid is attached to transmission case and extends into oil pump cover. PCM monitors TP voltage, vehicle speed and other input devices in order to determine when to energize TCC solenoid. Ignition voltage is supplied directly to solenoid through fused circuit. PCM commands solenoid on or off through ground circuit. DTC P0740 is set if PCM detects a continuous open or short to ground in TCC solenoid circuit.

Conditions For Setting DTC P0740

DTC will set under the following conditions

1. Ignition is on.
2. System voltage is 10-17 volts.
3. Engine is not in fuel cutoff mode.
4. Engine speed is more than 450 RPM for 8 seconds.
5. PCM commands solenoid on and voltage remains high (battery voltage).
6. PCM commands solenoid off and voltage remains low (zero volts).
7. All conditions are met for 5 seconds.

PCM performs the following if DTC is set

1. Will illuminate MIL at second consecutive failure signal.
2. Inhibits TCC engagement.
3. Inhibits 4th gear if in hot mode.
4. Freezes shift adapts from being updated.
5. DTC P0740 will be stored in PCM history.

Note. If PCM replacement is necessary, ensure new PCM is reprogrammed. See COMPUTER RELEARN PROCEDURES article in APPLICATIONS & IDENTIFICATION.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. If DTCs P0740, P0753, P0758, P0785 and P1860 are not present, go to next step. If DTCs P0740, P0753, P0758, P0785 and P1860 are present, remove appropriate TCC solenoid ignition feed circuit fuse from underhood electrical center and inspect fuse. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . Replace fuse if necessary, and check for short to ground in wiring harness between transmission 20-pin connector and fuse. Repair wiring as necessary, then go to step 10 . If fuse is okay, check for open in wiring harness between transmission 20-way connector and fuse. Repair wire as necessary, then go to step 10 .
3. Turn ignition off. Disconnect transmission 20-pin connector. Install Jumper Harness (J-39775) to PCM side of transmission 20-pin connector. Connect test light between ground and TCC solenoid ignition feed circuit at transmission 20-pin connector. Turn ignition switch to ON position. Do not start engine.
4. If test light does not illuminate, check for open or short to ground in ignition feed circuit of TCC solenoid. Repair as necessary, then go to step 10 . If test light does illuminate, connect test light between TCC solenoid ground circuit and ignition feed circuit at transmission 20-pin connector. Using scan tool, command TCC solenoid on and off 3 times.
5. If test light cycles on and off, go to next step. If test light does not cycle on and off 3 times, check TCC solenoid ground circuit for open or short to ground. Repair circuit as necessary, then go to step 10 . If circuit is okay, inspect wiring for poor connections at PCM connector. Check for bent, backed out, deformed or damaged terminals. Repair as necessary, then go to step 10 . If connections and terminals are okay, replace PCM. Ensure PCM is reprogrammed. Go to step 10 .
6. Turn ignition off. Disconnect jumper harness from PCM side of transmission 20-pin connector and install harness to transmission side of 20-pin connector. Connect ohmmeter between TCC solenoid ground circuit and ignition feed circuit at transmission 20-pin connector.
7. If resistance is 21-33 ohms, go to next step. If resistance is not 21-33 ohms, disconnect TCC solenoid connector. Measure resistance between TCC solenoid terminals. If resistance is 21-33 ohms, check for open circuit in transmission wiring harness. Repair as necessary, then go to step 10 . If resistance is not 21-33 ohms, replace TCC solenoid, then go to step 10 .
8. Turn ignition off. Connect ohmmeter between ground and TCC solenoid ground circuit, and between ground and TCC solenoid ignition feed circuit at transmission 20-pin connector. If resistance is more than 250 k/ohms, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If resistance is less than 250 k/ohms, go to next step.
9. Disconnect TCC solenoid connector. Measure resistance between ground and each solenoid terminal. If resistance is more than 250k/ohms, check for short to ground in transmission wiring harness. Repair as necessary, then go to next step. If resistance is less than 250 k/ohms, replace TCC solenoid, then go to next step.
10. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Test drive vehicle. Ensure voltage decreases to zero when TCC solenoid is commanded on, and voltage increases to battery voltage when commanded off. Conditions must be met for 5 seconds. Select Specific DTC and enter DTC "P0740". If DTC P0740 is not present, repair is complete. If DTC P0740 is still present, repeat test.

Inspect wiring for poor connections at PCM and transmission 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0742: TCC CIRCUIT INOPERATIVE (STUCK ON)

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS in section No. 1.

Torque Converter Clutch (TCC) solenoid stops converter signal oil exhaust. PCM commands solenoid on and off through ground circuit. When TCC solenoid is de-energized, solenoid will release fluid and release TCC. DTC P0742 is set if PCM detects a low torque converter slip when TCC is off.

Conditions For Setting DTC P0742

DTC will set under the following conditions

1. DTCs P0101, P0102 or P0103 (MAF sensor) are not present (if applicable).
2. DTCs P0107 or P0108 (MAP sensor) are not present.
3. DTCs P0122 or P0123 (throttle position sensor) are not present.
4. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
5. DTC P0740 (TCC solenoid) is not present.
6. DTC P1810 (TFP manual valve position switch) is not present.
7. DTC P1860 (TCC PWM solenoid) is not present.
8. Throttle position is 15-45 percent.
9. Engine speed is more than 450 RPM and less than 5500 RPM for more than 2 seconds.
10. Commanded gear is not 1st.
11. TCC is commanded off.
12. Gear range is "D4".
13. TCC slip speed is -20 to 20 RPM for more than 5.6 seconds.

PCM performs the following if DTC is set

1. Will illuminate MIL at second consecutive failure signal.
2. Freezes shift adapts from being updated.
3. DTC P0742 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Using scan tool, verify TP sensor value is within .6-5.0 volts. If TP sensor voltage is as specified, go to next step. If TP sensor voltage is not as specified, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
3. Drive vehicle in "D4" range in 4th gear under steady acceleration with TP angle more than 25 percent. Select "TCC Solenoid" state on scan tool. If scan tool displays TCC slip speed of -20 to 50 RPM (3.8L) or -20 to 30 RPM (all except 3.8L) in off state, go to next step. If scan tool does not display TCC slip speed of -20 to 50 RPM (3.8L) or -20 to 30 RPM (all except 3.8L) in off state, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
4. TCC is mechanically stuck on. Inspect TCC for a clogged exhaust orifice in TCC solenoid, converter clutch apply valve stuck in apply position, misaligned or damaged valve body gasket, or a restricted release passage. Repair component as necessary, then go to next step.
5. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Hold throttle angle at 25 percent. Accelerate vehicle to 55 MPH. If throttle moves more than 3 percent, stop vehicle and start again. Ensure TCC slip speed is between 100 to 2000 RPM (2.2L, 3.8L, 4.3L, 4.8L and 5.3L) or 130 to 2000 RPM (5.7L) RPM for 4 seconds with TCC off. Select Specific DTC and enter DTC "P0742". If DTC P0742 is not present, repair is complete. If DTC P0742 is still present, repeat test.

TCC may mechanically stick on with parking brake applied and any gear range selected. TCC fluid will mechanically apply TCC, which may cause engine to stall. A stuck TP sensor will set DTC P0742.

DTC P0748: PRESSURE CONTROL SOLENOID (PCS) ELECTRICAL MALFUNCTION

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Pressure Control Solenoid (PCS) is used to regulate transmission line pressure. PCM compares TP voltage, engine RPM and other inputs to determine appropriate line pressure for given load. PCM will regulate pressure by applying varying amperage to PCS. Applied amperage can vary from 0.1-1.0 amps. PCM then monitors amperage. DTC P0748 is set if PCM detects a continuous open or short to ground in PCS circuit.

Conditions For Setting DTC P0748

DTC will set under the following conditions

1. System voltage is 10-17 volts.
2. PCM recognizes PCS has reached high or low duty cycle limit.

PCM performs the following if DTC is set

1. Will not illuminate MIL when fault is set.
2. Freezes shift adapts from being updated.
3. DTC P0748 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Start engine. Using scan tool, apply 0.1-1.0 amp and observe scan tool display. If PCS actual amperage reading is not within 0.16 amps of desired reference amperage reading, go to next step. If PCS actual amperage reading is within 0.16 amps of desired reference amperage reading, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
3. Turn ignition off. Disconnect transmission 20-pin connector. Install Jumper Harness (J-39775) to transmission side of 20-pin connector. Using an ohmmeter, measure resistance of PCS between PCS terminals of jumper harness. If resistance is 3-7 ohms, go to step 5 .
4. If resistance is not 3-7 ohms, remove transmission oil pan. Disconnect PCS connector. Measure resistance between PCS terminals. If resistance is 3-7 ohms, check for open in PCS wiring harness. Repair wiring as necessary, then go to step 6 . If resistance is not 3-7 ohms, replace PCS, then go to step 6 .
5. Check PCS circuits for poor connection, open or short to ground. Repair circuits as necessary, then go to next step. If circuits are okay, check for damaged or backed out PCM connector terminals. Repair as necessary, then go to next step. If connector terminals are okay, replace PCM. Ensure PCM is reprogrammed. Go to next step.
6. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Ensure duty cycle is not at low or high limit. Select Specific DTC and enter DTC "P0748". If DTC P0748 is not present, repair is complete. If DTC P0748 is still present, repeat test.

Inspect wiring for poor connections at PCM and at transmission 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0751: 1-2 SHIFT SOLENOID ("A") PERFORMANCE MALFUNCTION

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

The 1-2 shift solenoid (solenoid "A") is a normally open exhaust valve that is used in conjunction with 2-3 shift solenoid (solenoid "B"), to allow 4 different shifting combinations. Solenoid is attached to control valve body. DTC P0751 is set if PCM detects a 1 - 1-4 - 4 or a 2 - 2-3 - 3 shift pattern, depending on mechanical failure.

Conditions For Setting DTC P0751

DTC will set under the following conditions

1. DTCs P0122 or P0123 (throttle position sensor) are not present.
2. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
3. DTC P0740 (TCC solenoid) is not present.
4. DTC P0742 (TCC stuck on) is not present.
5. DTCs P0753 and P0758 (1-2 and 2-3 shift solenoid electrical) are not present.
6. DTC P0785 (3-2 shift solenoid) is not present.
7. DTC P1810 (Temperature Fluid Pressure position switch) is not present.
8. DTC P1860 (TCC PWM solenoid) is not present.
9. Gear range is "D4".
10. Vehicle speed is more than 5 MPH.
11. Transmission fluid temperature is 68-266°F (20-130°C).
12. Traction control is not active (if equipped).
13. All conditions have been met and any combination of the following conditions occur 3 consecutive times

Condition No. 1

1. Commanded 4th gear.
2. TCC is on.
3. Throttle angle is 10-35 percent.
4. Speed ratio (engine speed divided by output speed) is .95-1.2.
5. TCC slip speed is 200-1000 RPM for more than 4 seconds.

Condition No. 2

1. Commanded 4th gear.
2. TCC is on.
3. Throttle angle is 10-35 percent.
4. Speed ratio (engine speed divided by output speed) is .65-.80.
5. TCC slip speed is between -20 and 55 RPM for more than 4 seconds.

PCM performs the following if DTC is set

1. Will illuminate MIL at first failure signal.
2. Freezes shift adapts from being updated.
3. Defaults line pressure to "D2".
4. DTC P0751 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Start engine and let idle. Apply parking brake. While observing scan tool, shift transmission into each gear position. If gear position matches transmission range switch on scan tool, go to next step. If gear position does not match transmission range switch on scan tool, diagnose Transmission Fluid Pressure (TFP) manual valve position switch. Switch is also referred to as Pressure Switch Assembly (PSA). See «COMPONENT TESTS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
3. Raise and support vehicle. Shift gear selector into "D4" position. Using scan tool, command 1st, 2nd, 3rd and 4th gears while accelerating vehicle. If a 1 - 1-4 - 4 or 2 - 2-3 - 3 shift pattern is not detected, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If a 1 - 1-4 - 4 or 2 - 2-3 - 3 shift pattern is detected, check shift solenoids for damaged seals or internal malfunction. Repair shift solenoids as necessary, then go to next step.
4. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Test drive vehicle. Hold throttle at 20 percent and accelerate vehicle to 55 MPH. If throttle moves more than 3 percent, stop vehicle and start again. Drive vehicle at 55 MPH for 2 miles. Select Specific DTC and enter DTC "P0751". If DTC P0751 is not present, repair is complete. If DTC P0751 is still present, repeat test.

Verify shift speeds are correct. See HYDRA-MATIC 4L60-E OVERHAUL article. More than one shift may occur due to other internal transmission failures.

DTC P0753: 1-2 SHIFT SOLENOID ("A") ELECTRICAL MALFUNCTION

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

The 1-2 shift solenoid (solenoid "A") is used to control fluid flow acting on 1-2 and 3-4 shift valves. Solenoid is a normally-open exhaust valve that is used in conjunction with 2-3 shift solenoid (solenoid "B"), to allow 4 different shifting combinations. See SHIFT SOLENOID COMBINATIONS table. Solenoid is attached to control valve body. Ignition voltage is supplied directly to solenoid through fused circuit. PCM commands solenoid on or off through ground circuit. DTC P0753 is set if PCM detects a continuous open or short to ground in 1-2 shift solenoid circuit.

Conditions For Setting DTC P0753

DTC will set under the following conditions

1. Ignition is on.
2. System voltage is 10-17 volts.
3. Engine is not in fuel cutoff mode.
4. Engine speed is more than 450 RPM for 5 seconds.
5. PCM commands solenoid on and voltage remains high (battery voltage).
6. PCM commands solenoid off and voltage remains low (zero volts).
7. All conditions are met for 5 seconds.

PCM performs the following if DTC is set

1. Will illuminate MIL at first failure signal.
2. Freezes shift adapts from being updated.
3. Defaults to "D2" line pressure.
4. DTC P0753 will be stored in PCM history.

SHIFT SOLENOID COMBINATIONS

Note. If PCM replacement is necessary, ensure new PCM is reprogrammed. See COMPUTER RELEARN PROCEDURES article in APPLICATIONS & IDENTIFICATION.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. If DTCs P0740, P0753, P0758, P0785 and P1860 are not present, go to next step. If DTCs P0740, P0753, P0758, P0785 and P1860 are present, remove appropriate 1-2 shift solenoid ignition feed circuit fuse from underhood electrical center and inspect fuse. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . Replace fuse if necessary, and check for short to ground in wiring harness between transmission 20-pin connector and fuse. Repair wiring as necessary, then go to step 12 . If fuse is okay, check for open in wiring harness between transmission 20-way connector and fuse. Repair wire as necessary, then go to step 12 .
3. Using scan tool, command 1-2 shift solenoid on and off 3 times while listening at transmission oil pan. If solenoid does not click when commanded on and off, go to next step. If solenoid clicks when commanded on and off, inspect wiring for poor connections at PCM and transmission 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Repair as necessary, then go to step 12 . If connections and terminals are okay, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
4. Turn ignition off. Disconnect transmission 20-pin connector. Install Jumper Harness (J-39775) to PCM side of transmission 20-pin connector. Connect test light between ground and 1-2 shift solenoid ignition feed circuit at transmission 20-pin connector. Turn ignition switch to ON position. Do not start engine.
5. If test light does not illuminate, check for open or short to ground in ignition feed circuit of 1-2 shift solenoid. Repair as necessary, then go to step 12 . If test light illuminates, connect test light between 1-2 shift solenoid ground circuit and ignition feed circuit at transmission 20-pin connector. Using scan tool, command 1-2 shift solenoid on and off 3 times. If test light cycles on and off, go to step 8 . If test light does not cycle on and off 3 times, and test light is always on, go to next step. If test light is always off, go to step 7 .
6. Check 1-2 shift solenoid ground circuit for short to ground. Repair circuit as necessary, then go to step 12 . If circuit is okay, inspect wiring for poor connections at PCM connector. Check for bent, backed out, deformed or damaged terminals. Repair as necessary, then go to step 12 . If connections and terminals are okay, replace PCM. Ensure PCM is reprogrammed. Go to step 12 .
7. Check for open in 1-2 shift solenoid ignition feed circuit or poor connection at PCM connector. Repair circuit as necessary, then go to step 12 . If circuit is okay, inspect wiring for poor connections at PCM connector. Check for bent, backed out, deformed or damaged terminals. Repair as necessary, then go to step 12 . If connections and terminals are okay, replace PCM. Ensure PCM is reprogrammed. Go to step 12 .
8. Turn ignition off. Disconnect jumper harness from PCM side of transmission 20-pin connector and install harness to transmission side of 20-pin connector. Connect ohmmeter between 1-2 shift solenoid ground circuit and ignition feed circuit at transmission 20-pin connector.
9. If resistance is 19-31 ohms, go to next step. If resistance is not 19-31 ohms, disconnect 1-2 shift solenoid connector. Measure resistance between 1-2 shift solenoid terminals. If resistance is 19-31 ohms, check for open circuit in transmission wiring harness. Repair as necessary, then go to step 12 . If resistance is not 19-31 ohms, replace 1-2 shift solenoid, then go to step 12 .
10. Turn ignition off. Connect ohmmeter between ground and 1-2 shift solenoid ground circuit, and between ground and 1-2 shift solenoid ignition feed circuit at transmission 20-pin connector. If resistance is more than 250 k/ohms, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If resistance is less than 250 k/ohms, go to next step.
11. Disconnect 1-2 shift solenoid connector. Measure resistance between ground and each solenoid terminal. If resistance is more than 250 k/ohms, check for short to ground in transmission wiring harness. Repair as necessary, then go to next step. If resistance is less than 250 k/ohms, replace 1-2 shift solenoid, then go to next step.
12. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Test drive vehicle. Ensure voltage decreases to zero when 1-2 shift solenoid is commanded on, and voltage increases to battery voltage when commanded off. Conditions must be met for 5 seconds. Select Specific DTC and enter DTC "P0753". If DTC P0753 is not present, repair is complete. If DTC P0753 is still present, repeat test.

Inspect wiring for poor connections at PCM. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0756: 2-3 SHIFT SOLENOID ("B") PERFORMANCE MALFUNCTION

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

The 2-3 shift solenoid (solenoid "B") is a normally open exhaust valve that is used in conjunction with 1-2 shift solenoid (solenoid "A"), to allow 4 different shifting combinations. Solenoid is attached to control valve body. DTC P0756 is set if PCM detects a 1-2-2-1 or a 4-3-3-4 shift pattern, depending on mechanical failure.

Conditions For Setting DTC P0756

DTC will set under the following conditions

1. DTCs P0101, P0102 or P0103 (MAF) are not present.
2. DTCs P0122 or P0123 (throttle position sensor) are not present.
3. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
4. DTCs P0711, P0712 or P0713 (TFT) are not present (All light trucks and vans).
5. DTC P0740 (TCC solenoid) is not present.
6. DTC P0742 (TCC stuck on) is not present.
7. DTCs P0753 and P0758 (1-2 and 2-3 shift solenoid electrical) are not present.
8. DTC P0785 (3-2 shift solenoid) is not present.
9. DTC P1810 (temperature fluid pressure position switch) is not present.
10. DTC P1860 (TCC PWM solenoid) is not present.
11. Gear range is "D4".
12. TCC is off.
13. Vehicle speed is more than 5 MPH.
14. Engine is not in fuel cutoff mode.
15. Transmission fluid temperature is 68-266°F (20-130°C).
16. Engine speed is more than 450 RPM for 2 seconds and less than 5500 RPM.
17. All conditions are met and either one of the following fail conditions occurs

1. 1st gear is commanded for 1.5 seconds.
2. Throttle angle is more than 25 percent.
3. Speed ratio (engine speed divided by output speed) is .7-3.0.
4. TCC slip speed is -3000 to 0 RPM for 1.6 seconds (3.8L and light trucks and vans).
5. TCC slip speed is -2000 to 0 RPM for 1.6 seconds (5.7L Corvette).
6. Transmission output speed is 400-1500 RPM.

1. 4th gear is commanded for one second.
2. Throttle angle is more than 18 percent.
3. Speed ratio (engine speed divided by output speed) is 1.68-3.0.
4. TCC slip speed is 1000-3000 RPM for 3 seconds.
5. Transmission output speed is 1400-2500 RPM (3.8L).
6. Transmission output speed is 1000-3000 RPM (5.7L).

PCM performs the following if DTC is set

1. Will light MIL at first failure signal.
2. Commands 3rd gear.
3. Freezes shift adapts from being updated.
4. Commands maximum line pressure.
5. DTC P0756 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Start engine and let idle. Apply parking brake. While observing scan tool, shift transmission into each gear position. If gear position matches transmission range switch on scan tool, go to next step. If gear position does not match transmission range switch on scan tool, diagnose Transmission Fluid Pressure (TFP) manual valve position switch. Switch is also referred to as Pressure Switch Assembly (PSA). See «COMPONENT TESTS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
3. Raise and support vehicle. Shift gear selector into "D4" position. Using scan tool, command 1st, 2nd, 3rd and 4th gears while accelerating vehicle. If 1st gear was commanded but not achieved or gear other than 4th gear occurred in 4th gear, check shift solenoids for damaged seals or internal malfunction. Repair shift solenoids as necessary, then go to next step. If all gears commanded were achieved, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
4. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Test drive vehicle. Hold throttle at 50 percent and accelerate vehicle to 55 MPH. If throttle moves more than 3 percent, stop vehicle and start again. Hold throttle at 20 percent and accelerate vehicle to 55 MPH. Select Specific DTC and enter DTC "P0756". If DTC P0756 is not present, repair is complete. If DTC P0756 is still present, repeat test.

Verify shift speeds are correct. See HYDRA-MATIC 4L60-E OVERHAUL article. More than one shift may occur due to other internal transmission failures.

DTC P0758: 2-3 SHIFT SOLENOID ("B") ELECTRICAL MALFUNCTION

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

The 2-3 shift solenoid (solenoid "B") is used to control fluid flow acting on 2-3 shift valve. Solenoid is a normally open exhaust valve that is used in conjunction with 1-2 shift solenoid (solenoid "A"), to allow 4 different shifting combinations. See SHIFT SOLENOID COMBINATIONS table. Solenoid is attached to control valve body. Ignition voltage is supplied directly to solenoid through fused circuit. PCM commands solenoid on or off through ground circuit. DTC P0758 is set if PCM detects a continuous open or short to ground in 2-3 shift solenoid circuit.

Conditions For Setting DTC P0758

DTC will set under the following conditions

1. Ignition is on.
2. System voltage is 10-17 volts.
3. PCM commands solenoid on and voltage remains high (battery voltage).
4. PCM commands solenoid off and voltage remains low (zero volts).
5. All conditions are met for 5 seconds.

PCM performs the following if DTC is set

1. Will light MIL at first failure signal.
2. Inhibits TCC engagement.
3. Freezes shift adapts from being updated.
4. Commands maximum line pressure.
5. Transmission operates in 3rd gear only.
6. DTC P0758 will be stored in PCM history.

SHIFT SOLENOID COMBINATIONS

Note. If PCM replacement is necessary, ensure new PCM is reprogrammed. See COMPUTER RELEARN PROCEDURES article in APPLICATIONS & IDENTIFICATION.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. If DTCs P0740, P0753, P0758, P0785 and P1860 are not present, go to next step. If DTCs P0740, P0753, P0758, P0785 and P1860 are present, remove appropriate 2-3 shift solenoid ignition feed circuit fuse from underhood electrical center and inspect fuse. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . Replace fuse if necessary, and check for short to ground in wiring harness between transmission 20-pin connector and fuse. Repair wiring as necessary, then go to step 12 . If fuse is okay, check for open in wiring harness between transmission 20-way connector and fuse. Repair wire as necessary, then go to step 12 .
3. Using scan tool, command 2-3 shift solenoid on and off 3 times while listening at transmission oil pan. If solenoid does not click when commanded on and off, go to next step. If solenoid clicks when commanded on and off, inspect wiring for poor connections at PCM and transmission 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Repair as necessary, then go to step 12 . If connections and terminals are okay, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
4. Turn ignition off. Disconnect transmission 20-pin connector. Install Jumper Harness (J-39775) to PCM side of transmission 20-pin connector. Connect test light between ground and 2-3 shift solenoid ignition feed circuit at transmission 20-pin connector. Turn ignition switch to ON position. Do not start engine.
5. If test light does not illuminate, check for open or short to ground in ignition feed circuit of 2-3 shift solenoid. Repair as necessary, then go to step 12 . If test light illuminates, connect test light between 2-3 shift solenoid ground circuit and ignition feed circuit at transmission 20-pin connector. Using scan tool, command 2-3 shift solenoid on and off 3 times. If test light cycles on and off, go to step 8 . If test light does not cycle on and off 3 times, and test light is always on, go to next step. If test light is always off, go to step 7 .
6. Check 2-3 shift solenoid ground circuit for short to ground. Repair circuit as necessary, then go to step 12 . If circuit is okay, inspect wiring for poor connections at PCM connector. Check for bent, backed out, deformed or damaged terminals. Repair as necessary, then go to step 12 . If connections and terminals are okay, replace PCM. Ensure PCM is reprogrammed. Go to step 12 .
7. Check for open in 2-3 shift solenoid ignition feed circuit or poor connection at PCM connector. Repair circuit as necessary, then go to step 12 . If circuit is okay, inspect wiring for poor connections at PCM connector. Check for bent, backed out, deformed or damaged terminals. Repair as necessary, then go to step 12 . If connections and terminals are okay, replace PCM. Ensure PCM is reprogrammed. Go to step 12 .
8. Turn ignition off. Disconnect jumper harness from PCM side of transmission 20-pin connector and install harness to transmission side of 20-pin connector. Connect ohmmeter between 2-3 shift solenoid ground circuit and ignition feed circuit at transmission 20-pin connector.
9. If resistance is 19-31 ohms, go to next step. If resistance is not 19-31 ohms, disconnect 2-3 shift solenoid connector. Measure resistance between 2-3 shift solenoid terminals. If resistance is 19-31 ohms, check for open circuit in transmission wiring harness. Repair as necessary, then go to step 12 . If resistance is not 19-31 ohms, replace 2-3 shift solenoid, then go to step 12 .
10. Turn ignition off. Connect ohmmeter between ground and 2-3 shift solenoid ground circuit, and between ground and 2-3 shift solenoid ignition feed circuit at transmission 20-pin connector. If resistance is more than 250 k/ohms, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If resistance is less than 250 k/ohms, go to next step.
11. Disconnect 2-3 shift solenoid connector. Measure resistance between ground and each solenoid terminal. If resistance is more than 250 k/ohms, check for short to ground in transmission wiring harness. Repair as necessary, then go to next step. If resistance is less than 250 k/ohms, replace 2-3 shift solenoid, then go to next step.
12. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Test drive vehicle. Ensure voltage decreases to zero when 2-3 shift solenoid is commanded on, and voltage increases to battery voltage when commanded off. Conditions must be met for 5 seconds. Select Specific DTC and enter DTC "P0758". If DTC P0758 is not present, repair is complete. If DTC P0758 is still present, repeat test.

Inspect wiring for poor connections at PCM. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0785: 3-2 SHIFT SOLENOID ELECTRICAL MALFUNCTION

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

The 3-2 shift solenoid is a normally-closed 3-port on/off device which controls 3-2 downshift. Ignition voltage is supplied directly to solenoid through fused circuit. PCM commands solenoid on or off through ground circuit. During 3-2 downshift, 2-4 band applies as 3-4 clutch releases. PCM varies timing between 3-4 clutch release and 2-4 band apply depending on vehicle speed and throttle position. DTC P0785 is set if PCM detects a continuous open or short to ground in 3-2 shift solenoid circuit.

Conditions For Setting DTC P0785

DTC will set under the following conditions

1. System voltage is 10-17 volts.
2. Ignition is on.
3. Engine is not in fuel cutoff mode.
4. Engine speed is more than 450 RPM for 5 seconds.
5. PCM commands solenoid on and voltage remains high (battery voltage).
6. PCM commands solenoid off and voltage remains low (zero voltage).
7. All conditions are met for 5 seconds.

PCM performs the following if DTC is set

1. Will illuminate MIL at first failure signal.
2. Inhibits TCC engagement.
3. Inhibits 4th gear if in hot mode.
4. Freezes shift adapts from being updated.
5. Commands maximum line pressure.
6. Commands a soft shift to 3rd gear.
7. DTC P0785 will be stored in PCM history.

Note. If PCM replacement is necessary, ensure new PCM is reprogrammed. See COMPUTER RELEARN PROCEDURES article in APPLICATIONS & IDENTIFICATION.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. If DTCs P0740, P0753, P0758, P0785 and P1860 are not present, go to next step. If DTCs P0740, P0753, P0758, P0785 and P1860 are present, remove appropriate 3-2 shift solenoid ignition feed circuit fuse from underhood electrical center and inspect fuse. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . Replace fuse if necessary, and check for short to ground in wiring harness between transmission 20-pin connector and fuse. Repair wiring as necessary, then go to step 10 . If fuse is okay, check for open in wiring harness between transmission 20-way connector and fuse. Repair wire as necessary, then go to step 10 .
3. Using scan tool, command 3-2 shift solenoid on and off 3 times while listening at transmission oil pan. If solenoid cycles, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If solenoid does not cycle, turn ignition off. Disconnect transmission 20-pin connector. Install Jumper Harness (J-39775) to PCM side of transmission 20-pin connector. Connect test light between ground and 3-2 shift solenoid ignition feed circuit at transmission 20-pin connector. Turn ignition switch to ON position. Do not start engine.
4. If test light does not illuminate, check for open or short to ground in ignition feed circuit of 3-2 shift solenoid. Repair as necessary, then go to step 10 . If test light illuminates, connect test light between 3-2 shift solenoid ground circuit and ignition feed circuit at transmission 20-pin connector. Using scan tool, command 3-2 shift solenoid on and off 3 times.
5. If test light cycles on and off, go to next step. If test light does not cycle on and off 3 times, check 3-2 shift solenoid ground circuit for open or short to ground. Repair circuit as necessary, then go to step 10 . If circuit is okay, inspect wiring for poor connections at PCM connector. Check for bent, backed out, deformed or damaged terminals. Repair as necessary, then go to step 10 . If connections and terminals are okay, replace PCM. Ensure PCM is reprogrammed. Go to step 10 .
6. Turn ignition off. Disconnect jumper harness from PCM side of transmission 20-pin connector and install harness to transmission side of 20-pin connector. Connect ohmmeter between 3-2 shift solenoid ground circuit and ignition feed circuit at transmission 20-pin connector.
7. If resistance is 20-32 ohms, go to next step. If resistance is not 20-32 ohms, disconnect 3-2 shift solenoid connector. Measure resistance between 3-2 shift solenoid terminals. If resistance is 20-32 ohms, check for open circuit in transmission wiring harness. Repair as necessary, then go to step 10 . If resistance is not 20-32 ohms, replace 3-2 shift solenoid, then go to step 10 .
8. Turn ignition off. Connect ohmmeter between ground and 3-2 shift solenoid ground circuit, and between ground and 3-2 shift solenoid ignition feed circuit at transmission 20-pin connector. If resistance is more than 250 k/ohms, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If resistance is less than 250 k/ohms, go to next step.
9. Disconnect 3-2 shift solenoid connector. Measure resistance between ground and each solenoid terminal. If resistance is more than 250 k/ohms, check for short to ground in transmission wiring harness. Repair as necessary, then go to next step. If resistance is less than 250 k/ohms, replace 3-2 shift solenoid, then go to next step.
10. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Test drive vehicle. Ensure voltage decreases to zero when 3-2 shift solenoid is commanded on, and voltage increases to battery voltage when commanded off. Conditions must be met for 5 seconds. Select Specific DTC and enter DTC "P0785". If DTC P0785 is not present, repair is complete. If DTC P0785 is still present, repeat test.

Inspect wiring for poor connections at PCM and transmission 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P1810: TRANSMISSION FLUID PRESSURE (TFP) MANUAL VALVE POSITION SWITCH ASSEMBLY MALFUNCTION

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire terminal identifications, see WIRING DIAGRAMS . Transmission Fluid Pressure (TFP) manual valve position switch assembly may also be referred to as Pressure Switch Assembly (PSA).

Transmission Fluid Pressure (TFP) manual valve position switch assembly consists of 5 pressure switches and a Transmission Fluid Temperature (TFT) sensor. 2 switches are normally-closed. 3 other switches are normally-open. Complete assembly mounts on control valve body.

PCM supplies battery voltage to each range switch. PCM grounds one or more range switch signal circuit(s) through various combinations of pressure switches. PCM monitors combinations in order to detect what manual valve position has been selected. PCM compares actual voltage combination of switches to TFP manual valve position switch combination values stored in memory. TFP manual valve position switch cannot distinguish between Park and Neutral because monitored valve body pressures are identical. DTC P1810 is set if PCM detects an invalid state of TFP manual valve position switch. See TFP LOGIC table.

TFP LOGIC

Conditions For Setting DTC P1810

DTC will set when any one of the following 3 conditions occur

This condition detects an illegal switch combination.

1. System voltage is 10-17 volts.
2. Engine is running.
3. Engine is not in fuel cutoff mode.
4. PCM detects an illegal TFP state.
5. All conditions are met for one minute.

This condition detects "D2", "D4" or Reverse during an engine start.

1. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
2. Engine speed is less than 100 RPM for .3 seconds, then engine speed is between 100-600 RPM for .3 seconds, then engine speed is more than 600 RPM for 3 seconds.
3. Vehicle speed is less than 4 MPH.
4. Detected gear range is "D2", "D4" or Reverse.
5. All conditions are met for 3 seconds.

Condition No. 3

This condition detects Park or Neutral when vehicle should be in "D4".

1. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
2. Engine speed is less than 2000 RPM.
3. Speed ratio (engine speed divided by output speed) is .39-.80.
4. TCC is locked on.
5. Detected gear range is Park or Neutral.
6. All conditions are met for 5 seconds.

PCM performs the following if DTC is set

1. Will illuminate MIL after 2 consecutive trips with failure.
2. Freezes shift adapts from being updated.
3. Defaults line pressure to "D2".
4. Defaults shift pattern to "D4".
5. DTC P1810 will be stored in PCM history.

Note. If PCM replacement is necessary, ensure new PCM is reprogrammed. See COMPUTER RELEARN PROCEDURES article in APPLICATIONS & IDENTIFICATION.

1. Check transmission fluid. Fill as needed. Ensure transmission shift linkage is adjusted correctly. Diagnose Transmission Fluid Pressure (TFP) manual valve position switch. Switch is also referred to as Pressure Switch Assembly (PSA). See «COMPONENT TESTS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Start engine and let idle. Apply parking brake. While observing scan tool, shift transmission into each gear position. If gear position matches transmission range switch on scan tool, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If gear position does not match transmission range switch on scan tool, go to next step.
3. Turn ignition off. Disconnect transmission 20-pin connector. Install Jumper Harness (J-39775) on PCM side of transmission 20-pin connector. Turn ignition switch to ON position. Do not start engine. Using a DVOM, measure voltage at range input circuits "A", "B" and "C" at transmission 20-pin connector. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If battery voltage is present at all circuits, go to step 5 . If battery voltage is not present at all circuits, go to next step.
4. Check each circuit which did not have battery voltage for open or short to ground. Repair circuit(s) as necessary, then go to step 6 . If all circuits are okay, inspect wiring for poor connections at appropriate PCM connector. Check for bent, backed out, deformed or damaged terminals. Repair as necessary, then go to step 6 . If connections and terminals are okay, replace PCM. Ensure PCM is reprogrammed. Go to step 6 .
5. Ensure circuits are not shorted together. Use a fused jumper to separately ground each circuit while monitoring scan tool TFP manual valve position switch A/B/C display. Repair circuits as necessary, then go to next step. If all circuits are okay, diagnose Transmission Fluid Pressure (TFP) manual valve position switch. See «COMPONENT TESTS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
6. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Select Specific DTC and enter DTC "P1810". Turn ignition switch to ON position for at least 2 seconds. Start vehicle and idle for 5 seconds. Drive vehicle in "D4" until TCC locks for 20 seconds. If DTC P1810 is not present, repair is complete. If DTC P1810 is still present, repeat test.

Inspect wiring for poor connections at PCM and at transmission 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Inspect for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P1860: TCC PWM SOLENOID ELECTRICAL MALFUNCTION

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

TCC PWM solenoid is used to control fluid flow acting on converter clutch valve. Solenoid controls TCC apply and release. Solenoid is attached to control valve body. Ignition voltage is supplied directly to solenoid through fused circuit. PCM commands solenoid on or off through ground circuit. TCC PWM solenoid provides a smooth engagement of TCC by operating during duty cycle percent of on time. DTC P1860 is set if PCM detects a continuous open or short to ground in TCC PWM solenoid circuit.

Conditions For Setting DTC P1860

DTC will set under the following conditions

1. 1st gear is commanded.
2. Ignition is on.
3. System voltage is 10-17 volts.
4. TCC is at 100 percent duty cycle for more than .1 second.
5. TCC is at zero percent duty cycle for more than 5 seconds.
6. PCM commands solenoid off and voltage remains low (zero volts).
7. All conditions are met for 5 seconds.

PCM performs the following if DTC is set

1. Will illuminate MIL at first failure signal.
2. Inhibits TCC engagement.
3. Inhibits 4th gear if in hot mode.
4. Freezes shift adapts from being updated.
5. DTC P1860 will be stored in PCM history.

Note. If PCM replacement is necessary, ensure new PCM is reprogrammed. See COMPUTER RELEARN PROCEDURES article in APPLICATIONS & IDENTIFICATION.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. If DTCs P0740, P0753, P0758, P0785 and P1860 are not present, go to next step. If DTCs P0740, P0753, P0758, P0785 and P1860 are present, remove appropriate TCC PWM solenoid ignition feed circuit fuse from underhood electrical center and inspect fuse. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . Replace fuse if necessary, and check for short to ground in wiring harness between transmission 20-pin connector and fuse. Repair wiring as necessary, then go to step 10 . If fuse is okay, check for open in wiring harness between transmission 20-way connector and fuse. Repair wire as necessary, then go to step 10 .
3. Turn ignition off. Disconnect transmission 20-pin connector. Install Jumper Harness (J-39775) to PCM side of transmission 20-pin connector. Connect test light between ground and TCC PWM solenoid ignition feed circuit at transmission 20-pin connector. Turn ignition switch to ON position. Do not start engine.
4. If test light does not illuminate, check for open or short to ground in ignition feed circuit of TCC PWM solenoid. Repair as necessary, then go to step 10 . If test light illuminates, connect test light between TCC PWM solenoid ground circuit and ignition feed circuit at transmission 20-pin connector. Using scan tool, command TCC PWM solenoid on and off 3 times.
5. If test light cycles on and off, go to next step. If test light does not cycle on and off 3 times, check TCC PWM solenoid ground circuit for open or short to ground. Repair circuit as necessary, then go to step 10 . If circuit is okay, inspect wiring for poor connections at PCM connector. Check for bent, backed out, deformed or damaged terminals. Repair as necessary, then go to step 10 . If connections and terminals are okay, replace PCM. Ensure PCM is reprogrammed. Go to step 10 .
6. Turn ignition off. Disconnect jumper harness from PCM side of transmission 20-pin connector and install harness to transmission side of 20-pin connector. Connect ohmmeter between TCC PWM solenoid ground circuit and ignition feed circuit at transmission 20-pin connector.
7. If resistance is 10-15 ohms, go to next step. If resistance is not 10-15 ohms, disconnect TCC PWM solenoid connector. Measure resistance between TCC PWM solenoid terminals. If resistance is 10-15 ohms, check for open circuit in transmission wiring harness. Repair as necessary, then go to step 10 . If resistance is not 10-15 ohms, replace TCC PWM solenoid, then go to step 10 .
8. Turn ignition off. Connect ohmmeter between ground and TCC PWM solenoid ground circuit, and between ground and TCC PWM solenoid ignition feed circuit at transmission 20-pin connector. If resistance is more than 250 k/ohms, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If resistance is less than 250 k/ohms, go to next step.
9. Disconnect TCC PWM solenoid connector. Measure resistance between ground and each solenoid terminal. If resistance is more than 250 k/ohms, check for short to ground in transmission wiring harness. Repair as necessary, then go to next step. If resistance is less than 250 k/ohms, replace TCC PWM solenoid, then go to next step.
10. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Test drive vehicle. Ensure voltage decreases to zero when TCC PWM solenoid is commanded on, and voltage increases to battery voltage when commanded off. Conditions must be met for 5 seconds. Select Specific DTC and enter DTC "P1860". If DTC P1860 is not present, repair is complete. If DTC P1860 is still present, repeat test.

Inspect wiring for poor connections at PCM and transmission 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P1870: TRANSMISSION COMPONENT SLIPPING

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

PCM monitors difference between engine speed and transmission output speed. In "D3" with TCC engaged, engine speed should closely match transmission output speed. In "D4" with TCC engaged, TCC slip speed should be -20 to 50 RPM (all models except Corvette) or -20 to 40 RPM (Corvette). DTC P1870 is set if PCM detects excessive TCC slip when TCC should be engaged.

Conditions For Setting DTC P1870

DTC will set under the following conditions

1. DTCs P0101, P0102 or P0103 (MAF) are not present.
2. DTCs P0711, P0712 or P0713 (TFT) are not present (4.3L, 4.8L and 5.3L).
3. DTCs P0122 or P0123 (throttle position sensor) are not present.
4. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
5. DTC P0740 (TCC solenoid) is not present.
6. DTC P0753 (1-2 shift solenoid) are not present.
7. DTC P0758 (2-3 shift solenoid) are not present.
8. DTC P1810 (TFP manual valve position switch) is not present.
9. DTC P1860 (TCC PWM solenoid) is not present.
10. Engine speed is 1200-3500 RPM.
11. Gear range is "D4".
12. Vehicle is not in 1st gear.
13. Throttle angle is 10-45 percent.
14. Transmission fluid temperature is 68-266°F (20-130°C).
15. TCC is on for 5 seconds.
16. TCC is at maximum apply for 2 seconds.
17. Shift solenoid performance counter is at zero.
18. TCC slip speed is more than 130 RPM for more than 8 seconds.

PCM performs the following if DTC is set

1. Will illuminate MIL at second consecutive failure signal.
2. Inhibits TCC engagement.
3. Inhibits 4th gear if in hot mode.
4. Freezes shift adapts from being updated.
5. Commands maximum line pressure.
6. DTC P1870 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Start engine and let idle. Apply parking brake. While observing scan tool, shift transmission into each gear position. If gear position matches transmission range switch on scan tool, go to next step. If gear position does not match transmission range switch on scan tool, diagnose Transmission Fluid Pressure (TFP) manual valve position switch. See «COMPONENT TESTS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
3. Drive vehicle in 4th gear while TCC is engaged. If TCC slip speed is more than 130 RPM for 10 seconds, go to TROUBLE SHOOTING in HYDRA-MATIC 4L60-E OVERHAUL article. If TCC slip speed is less than 130 RPM for 10 seconds, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .

A TFP manual valve position switch (Pressure Switch Assembly) malfunction could set DTC P1870. Ensure final drive ratio matches PCM calibration. The following mechanical conditions could set DTC P1870

1. Shift solenoids.
2. TCC solenoid.
3. TCC PWM solenoid.
4. Internal transmission failures.
5. Engine misfire.
6. Transmission range switch DTC.

The following diagnostic tests are DTC specific. Always perform On-Board Diagnostic (OBD) System Check prior to performing any diagnostic procedure. For PCM/VCM terminal locations (Scheme 11)- (Scheme 13) and WIRING DIAGRAMS. For engine-related DTCs, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.

Note. Vehicles equipped with 2.2L, 4.8L or 5.3L engines are equipped with a Powertrain Control Module (PCM). All other models are equipped with a Vehicle Control Module (VCM).

Diagnostic aids, located at end of each diagnostic test, are additional tips used to help diagnose trouble codes when diagnostic procedures do not find a problem.

PCM connector colors and terminal identification may vary with vehicle model and engine size. When using diagnostic tests, see appropriate wiring diagram to determine which PCM connector(s) to disconnect during test procedure. Locate component being tested and trace specified wiring circuit to determine PCM connector and terminal related to that component.

DTC P0218: TRANSMISSION FLUID OVERTEMPERATURE

Note. Refer to DIAGNOSTIC TESTS (PASSENGER CARS) for DTC test procedures. Light truck and van test procedures for this DTC are the same as passenger car test procedures.

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (LIGHT TRUCKS & VANS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Vehicle speed is signaled to PCM/VCM by Vehicle Speed Sensor (VSS). Sensor is a Permanent Magnet (PM) generator mounted to transmission case extension. PM generator produces an AC voltage as speed sensor rotor teeth pass sensor's magnetic field. PCM/VCM converts AC voltage into digital signal. Output voltage varies from a minimum of .5 volt at 100 RPM to more than 100 volts at 8000 RPM. PCM/VCM uses vehicle speed to determine shift timing and TCC apply and release. VSS resistance value is 1470-2820 ohms. DTC P0502 is set if PCM/VCM detects a low vehicle output speed when vehicle has high engine speed in drive gear.

DTC will set under the following conditions

1. Transmission is not in Park or Neutral.
2. DTCs P0101, P0102 and P0103 (MAF sensor) are not present (4.8L and 5.3L).
3. DTCs P0107 and P0108 (MAP sensor), or P0122 and P0123 (throttle position sensor) are not present.
4. DTC P1810 (trans. fluid pressure position switch) is not present.
5. Engine speed more than 3000 RPM.
6. Throttle angle is more than 20 percent.
7. Output speed is less than 150 RPM.
8. All conditions are met for 3 seconds.

Action Taken By PCM/VCM

PCM/VCM performs the following if DTC is set

1. Will illuminate MIL at first failure signal.
2. Commands 2nd gear only.
3. Inhibits TCC engagement.
4. Freezes shift adapts from being updated.
5. Commands maximum line pressure.
6. DTC P0502 will be stored in PCM/VCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Select DTC on scan tool. Select CLEAR INFO function.
2. Raise and support vehicle. Start engine and let idle. Disable traction control system (if equipped). Shift gear selector to any forward position. Select OUTPUT SPEED on scan tool. Allow drive wheels to rotate. If transmission output speed does not increase when wheel speed increases, go to next step. If transmission output speed increases when wheel speed increases, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
3. Turn ignition off. Disconnect appropriate PCM/VCM connector connected to VSS. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . Using an ohmmeter, measure resistance between VSS terminals at appropriate PCM/VCM connector. If resistance is 1377-3355 ohms (2WD) or 976-2354 (4WD), go to next step. If resistance is not as specified, go to step 6 .
4. Measure resistance between ground and VSS High terminal on appropriate PCM/VCM harness connector. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If resistance is greater that 50 k/ohms, go to next step. If resistance is not as specified, go to step 7 .
5. Connect voltmeter between VSS terminals at appropriate PCM/VCM connector terminals. Rotate drive wheels (ensure driveshaft is turning) and observe voltmeter display. If voltage is less than .5 volt, go to step 8 . If voltage is more than .5 volt, go to step 9 .
6. Disconnect VSS connector. Measure resistance between VSS component terminals. If resistance is 1377-3355 ohms (2WD) or 976-2354 (4WD) ohms, go to next step. If resistance is not as specified, replace VSS. Go to step 10 .
7. Inspect VSS High and Lo circuits between VSS connector and appropriate PCM/VCM harness connector for open or short to ground. Repair as needed. Go to step 10 . If both circuits are okay, go to «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
8. Remove VSS from transmission. Inspect output speed sensor rotor for damage or misalignment. Repair as necessary, then go to next step. If rotor is okay, replace VSS, then go to next step.
9. Check PCM/VCM connector for damaged or backed out connector terminals, weak terminal tension and poor connections. Repair as necessary, then go to next step. If terminals and connections are okay, replace PCM/VCM. Ensure PCM/VCM is reprogrammed. Go to next step.
10. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Select Specific DTC and enter DTC "P0502". Test drive vehicle. Ensure transmission output speed is more than 251 RPM for 2 seconds. If DTC P0502 is not present, repair is complete. If DTC P0502 is still present, repeat test.

DTC P0502 sets when no vehicle speed is detected at start-off. Check for Electromagnetic Interferences (EMI) induced on VSS circuits. Check PCM/VCM connector and transmission 20-pin connector for bent, backed out or broken terminals or misaligned connectors. Inspect for damaged VSS or for damaged output speed sensor rotor teeth. Ensure VSS is aligned correctly and secured to transmission case properly. An incorrect calibration may set DTC P0502. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value changes.

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (LIGHT TRUCKS & VANS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Vehicle speed is signaled to PCM/VCM by Vehicle Speed Sensor (VSS). Sensor is a Permanent Magnet (PM) generator mounted to transmission case extension. PM generator produces an AC voltage as speed sensor rotor teeth pass sensor's magnetic field. PCM/VCM converts AC voltage into digital signal. Output voltage varies from a minimum of .5 volt at 100 RPM to more than 100 volts at 8000 RPM. PCM/VCM uses vehicle speed to determine shift timing and TCC apply and release. DTC P0503 is set if PCM/VCM detects an unrealistically large drop in vehicle speed.

DTC will set under the following conditions

1. Engine is not in fuel cutoff mode.
2. Time since last gear range change is more than 6 seconds.
3. DTC P1810 (trans. fluid pressure position switch) is not present.
4. Engine speed more than 450 RPM for 5 seconds.
5. Transmission output speed rise does not exceed 600 RPM within 6 seconds.
6. Transmission output speed drops by more than 1300 RPM for 3 seconds when not in Park or Neutral.

PCM/VCM performs the following if DTC is set

1. Will illuminate MIL at first failure signal.
2. Commands 2nd gear only.
3. Inhibits TCC engagement.
4. Freezes shift adapts from being updated.
5. Commands maximum line pressure.
6. DTC P0503 will be stored in PCM/VCM history.

Note. If PCM/VCM replacement is necessary, ensure new PCM/VCM is reprogrammed. See appropriate COMPUTER RELEARN PROCEDURES under GENERAL INFORMATION in ENGINE PERFORMANCE.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Select DTC on scan tool. Select CLEAR INFO function.
2. Raise and support vehicle. Start engine and let idle. Disable traction control system (if equipped). Shift gear selector to D3 position. Select OUTPUT SPEED on scan tool. Allow drive wheels to rotate. Slowly accelerate until engine reaches 2000 RPM and hold speed. Transmission output speed should be about 1300 RPM. If output speed is maintained as specified, go to next step. If transmission output speed fluctuates above or below 1300 RPM, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
3. Turn ignition off. Disconnect appropriate PCM/VCM connector connected to VSS. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . Using an ohmmeter, measure resistance between VSS terminals at appropriate PCM/VCM connector. If resistance is 1377-3355 ohms (2WD) or 976-2354 (4WD), go to next step. If resistance is not as specified, go to step 6 .
4. Measure resistance between ground and VSS High terminal on appropriate PCM/VCM harness connector. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If resistance is greater that 50 k/ohms, go to next step. If resistance is not as specified, go to step 7 .
5. Connect voltmeter between VSS terminals at appropriate PCM/VCM connector terminals. Rotate drive wheels (ensure driveshaft is turning) and observe voltmeter display. If voltage is less than .5 volt, go to step 8 . If voltage is more than .5 volt, go to step 9 .
6. Disconnect VSS connector. Measure resistance between VSS component terminals. If resistance is 1377-3355 ohms (2WD) or 976-2354 (4WD) ohms, go to next step. If resistance is not as specified, replace VSS. Go to step 10 .
7. Inspect VSS High and Lo circuits between VSS connector and appropriate PCM/VCM harness connector for open or short to ground. Repair as needed. Go to step 10 . If both circuits are okay, go to «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) .
8. Remove VSS from transmission. Inspect output speed sensor rotor for damage or misalignment. Repair as necessary, then go to next step. If rotor is okay, replace VSS, then go to next step.
9. Check PCM/VCM connector for damaged or backed out connector terminals, weak terminal tension and poor connections. Repair as necessary, then go to next step. If terminals and connections are okay, replace PCM/VCM. Ensure PCM/VCM is reprogrammed. Go to next step.
10. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Select Specific DTC and enter DTC "P0503". Test drive vehicle. Ensure transmission output speed is more than 600 RPM for 3 seconds. If DTC P0503 is not present, repair is complete. If DTC P0503 is still present, repeat test.

Check PCM/VCM connector and transmission 20-pin connector for bent, backed out or broken terminals or misaligned connectors. Inspect for damaged VSS or for damaged output speed sensor rotor teeth. Check for moisture or corrosion. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value changes.

DTC P0711: TRANS. FLUID TEMPERATURE (TFT) SENSOR CIRCUIT (RANGE/PERFORMANCE)

Note. Refer to DIAGNOSTIC TESTS (PASSENGER CARS) for DTC test procedure. Light truck and van test procedures for this DTC are the same as passenger car test procedures. Any reference to PCM in testing includes VCM.

Note. Refer to DIAGNOSTIC TESTS (PASSENGER CARS) for DTC test procedure. Light truck and van test procedures for this DTC are the same as passenger car test procedures. Any reference to PCM in testing includes VCM.

Note. Refer to DIAGNOSTIC TESTS (PASSENGER CARS) for DTC test procedure. Light truck and van test procedures for this DTC are the same as passenger car test procedures. Any reference to PCM in testing includes VCM.

Note. Refer to DIAGNOSTIC TESTS (PASSENGER CARS) for DTC test procedure. Light truck and van test procedures for this DTC are the same as passenger car test procedures. Any reference to PCM in testing includes VCM.

DTC P0724: BRAKE SWITCH CIRCUIT LOW INPUT (SWITCH STUCK OFF)

Note. Refer to DIAGNOSTIC TESTS (PASSENGER CARS) for DTC test procedure. Light truck and van test procedures for this DTC are the same as passenger car test procedures. Any reference to PCM in testing includes VCM.

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (LIGHT TRUCKS & VANS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

In conjunction with TCC PWM solenoid, TCC solenoid is used to control fluid flow acting on TCC valve. TCC valve controls apply and release of TCC. Solenoid is a normally-open on/off device. Solenoid is attached to transmission case and extends into oil pump cover. PCM monitors TP voltage, vehicle speed and other input devices in order to determine when to energize TCC solenoid. Ignition voltage is supplied directly to solenoid through fused circuit. PCM commands solenoid on or off through ground circuit. DTC P0740 is set if PCM detects a continuous open or short to ground in TCC solenoid circuit.

DTC will set under the following conditions

1. Ignition is on.
2. System voltage is 10-17 volts.
3. Engine is not in fuel cutoff mode.
4. Engine speed is more than 450 RPM for 8 seconds.
5. PCM commands solenoid on and voltage remains high (battery voltage).
6. PCM commands solenoid off and voltage remains low (zero volts).
7. All conditions are met for 5 seconds.

PCM performs the following if DTC is set

1. Will illuminate MIL at second consecutive failure signal.
2. Inhibits TCC engagement.
3. Inhibits 4th gear if in hot mode.
4. Freezes shift adapts from being updated.
5. DTC P0740 will be stored in PCM history.

Note. If PCM replacement is necessary, ensure new PCM is reprogrammed. See COMPUTER RELEARN PROCEDURES article in APPLICATIONS & IDENTIFICATION.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. If DTCs P0740, P0753, P0758, P0785 and P1860 are not present, go to next step. If DTCs P0740, P0753, P0758, P0785 and P1860 are present, remove appropriate TCC solenoid ignition feed circuit fuse from underhood electrical center and inspect fuse. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . Replace fuse if necessary, and check for short to ground in wiring harness between transmission 20-pin connector and fuse. Repair wiring as necessary, then go to step 10 . If fuse is okay, check for open in wiring harness between transmission 20-way connector and fuse. Repair wire as necessary, then go to step 10 .
3. Turn ignition off. Disconnect transmission 20-pin connector. Install Jumper Harness (J-39775) to PCM/VCM side of transmission 20-pin connector. Connect test light between ground and TCC solenoid ignition feed circuit at transmission 20-pin connector. Turn ignition switch to ON position. Do not start engine.
4. If test light does not illuminate, check for open or short to ground in ignition feed circuit of TCC solenoid. Repair as necessary, then go to step 10 . If test light does illuminate, connect test light between TCC solenoid ground circuit and ignition feed circuit at transmission 20-pin connector. Using scan tool, command TCC solenoid on and off 3 times.
5. If test light cycles on and off, go to next step. If test light does not cycle on and off 3 times, check TCC solenoid ground circuit for open or short to ground. Repair circuit as necessary, then go to step 10 . If circuit is okay, inspect wiring for poor connections at PCM connector. Check for bent, backed out, deformed or damaged terminals. Repair as necessary, then go to step 10 . If connections and terminals are okay, replace PCM. Ensure PCM is reprogrammed. Go to step 10 .
6. Turn ignition off. Disconnect jumper harness from PCM side of transmission 20-pin connector and install harness to transmission side of 20-pin connector. Connect ohmmeter between TCC solenoid ground circuit and ignition feed circuit at transmission 20-pin connector.
7. If resistance is 21-33 ohms, go to next step. If resistance is not 21-33 ohms, disconnect TCC solenoid connector. Measure resistance between TCC solenoid terminals. If resistance is 21-33 ohms, check for open circuit in transmission wiring harness. Repair as necessary, then go to step 10 . If resistance is not 21-33 ohms, replace TCC solenoid, then go to step 10 .
8. Turn ignition off. Connect ohmmeter between ground and TCC solenoid ground circuit, and between ground and TCC solenoid ignition feed circuit at transmission 20-pin connector. If resistance is more than 250 k/ohms, see «DIAGNOSTIC AIDS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . If resistance is less than 250 k/ohms, go to next step.
9. Disconnect TCC solenoid connector. Measure resistance between ground and each solenoid terminal. If resistance is more than 250k/ohms, check for short to ground in transmission wiring harness. Repair as necessary, then go to next step. If resistance is less than 250 k/ohms, replace TCC solenoid, then go to next step.
10. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Test drive vehicle. Ensure voltage decreases to zero when TCC solenoid is commanded on, and voltage increases to battery voltage when commanded off. Conditions must be met for 5 seconds. Select Specific DTC and enter DTC "P0740". If DTC P0740 is not present, repair is complete. If DTC P0740 is still present, repeat test.

Inspect wiring for poor connections at PCM and transmission 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

Note. Refer to DIAGNOSTIC TESTS (PASSENGER CARS) for DTC test procedure. Light truck and van test procedures for this DTC are the same as passenger car test procedures. Any reference to PCM in testing includes VCM.

Note. Refer to DIAGNOSTIC TESTS (PASSENGER CARS) for DTC test procedure. Light truck and van test procedures for this DTC are the same as passenger car test procedures. Any reference to PCM in testing includes VCM.

Note. Refer to DIAGNOSTIC TESTS (PASSENGER CARS) for DTC test procedure. Light truck and van test procedures for this DTC are the same as passenger car test procedures. Any reference to PCM in testing includes VCM.

Note. Refer to DIAGNOSTIC TESTS (PASSENGER CARS) for DTC test procedure. Light truck and van test procedures for this DTC are the same as passenger car test procedures. Any reference to PCM in testing includes VCM.

Note. Refer to DIAGNOSTIC TESTS (PASSENGER CARS) for DTC test procedure. Light truck and van test procedures for this DTC are the same as passenger car test procedures. Any reference to PCM in testing includes VCM.

Note. Refer to DIAGNOSTIC TESTS (PASSENGER CARS) for DTC test procedure. Light truck and van test procedures for this DTC are the same as passenger car test procedures. Any reference to PCM in testing includes VCM.

Note. Refer to DIAGNOSTIC TESTS (PASSENGER CARS) for DTC test procedure. Light truck and van test procedures for this DTC are the same as passenger car test procedures. Any reference to PCM in testing includes VCM.

Note. Refer to DIAGNOSTIC TESTS (PASSENGER CARS) for DTC test procedure. Light truck and van test procedures for this DTC are the same as passenger car test procedures. Any reference to PCM in testing includes VCM.

Note. Refer to DIAGNOSTIC TESTS (PASSENGER CARS) for DTC test procedure. Light truck and van test procedures for this DTC are the same as passenger car test procedures. Any reference to PCM in testing includes VCM.

Note. Refer to DIAGNOSTIC TESTS (PASSENGER CARS) for DTC test procedure. Light truck and van test procedures for this DTC a7re the same as passenger car test procedures. Any reference to PCM in testing includes VCM.

DTC P1875: 4WD LOW CIRCUIT MALFUNCTION

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (LIGHT TRUCKS & VANS) prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Circuit Description (Non-Active 4WD System)

The 4WD low circuit consists of a transfer case switch, a front axle switch and a front axle actuator. When 4WD low is engaged, voltage to PCM/VCM changes from ignition voltage to zero. The 4WD low switch signal corrects transmission output speed signal to PCM/VCM. This signal compensates for transfer case gear reduction. PCM/VCM uses transmission output speed signal to adjust shift points, line pressure and TCC scheduling. DTC P1875 is set if PCM/VCM detects a continuous open or short to ground in 4WD circuit.

The 4WD low circuit consists of a transfer case selector switch, Transfer Case Control Module (TCCM) and wiring. When 4WD low is selected, TCCM receives a momentary signal from selector switch. If all conditions for 4WD low are met, TCCM allows electric motor in transfer case to perform shift. When 4WD low is engaged, voltage to PCM/VCM changes from ignition voltage to zero. The 4WD low switch signal corrects transmission output speed signal to PCM/VCM. This signal compensates for transfer case gear reduction. PCM/VCM uses transmission output speed signal to adjust shift points, line pressure and TCC scheduling. DTC P1875 is set if PCM/VCM detects a continuous open or short to ground in 4WD circuit.

Conditions For Setting DTC P1875

DTC will set under the following conditions

1. DTCs P0122 or P0123 (throttle position sensor) are not present.
2. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
3. DTC P0740 (TCC solenoid) is not present.
4. DTC P0742 (TCC stuck on) is not present.
5. DTC P0751 or P0753 (1-2 shift solenoid) is not present.
6. DTC P0576 or P0758 (2-3 shift solenoid) is not present.
7. DTC P1810 (trans. fluid pressure switch) is not present.
8. DTC P1860 (TCC PWM solenoid) is not present.
9. Engine speed is more than 450 RPM for 8 seconds.
10. Not in fuel cutoff mode.
11. Gear range is "D4".
12. Throttle angle is 17-50 percent.
13. Transmission fluid temperature is 68-248°F (20-120°C).
14. All of the above conditions are met and either of the following fail conditions occur

1. 4WD low is stuck on for 5 seconds.
2. TCC slip speed is -50 to -3000 RPM.
3. 4WD low is not engaged.
4. Speed ratio (engine speed divided by transfer case output speed) is .8-1.2.

1. 4WD low is stuck off for 10 seconds.
2. TCC is commanded on.
3. TCC slip speed is 100-3000 RPM.
4. 4WD low is engaged.
5. Speed ratio is 2.5-2.9.

PCM/VCM performs the following if DTC is set

1. Will illuminate MIL at first failure signal.
2. Commands a normal shift pattern.
3. DTC P1875 will be stored in PCM/VCM history.

Diagnostic Procedure (Non-Active 4WD System)

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Set parking brake and block drive wheels. Shift transmission into Neutral. While observing scan tool 4WD low display, select 4HI on transfer case selector switch, then select 4LO on transfer case selector switch. If scan tool 4WD low does not display DISABLED when 4HI is selected and ENABLED when 4LO is selected, go to next step. If scan tool 4WD low displays DISABLED when 4HI is selected and ENABLED when 4LO is selected, see «DIAGNOSTIC AIDS (ALL MODELS)»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__diagnostic-aids-all-models) .
3. Turn ignition off. Disconnect transfer case switch connector. Turn ignition switch to ON position. If scan tool 4WD low does not indicate ENABLED, go to next step. If scan tool 4WD low indicates ENABLED, check for short to ground in Gray/Black wire. Repair as necessary, then go to step 6 . If wire is okay, check PCM/VCM connector for bent, backed out, deformed or damaged terminals. Repair as necessary, then go to step 6 . If terminals and connections are okay, replace PCM/VCM, then go to step 6 .
4. Connect terminal "B" (Gray/Black wire) of transfer case selector switch connector to known-good ground. Observe scan tool 4WD low. If scan tool 4WD low indicates ENABLED when circuit is grounded, replace transfer case selector switch, then go to step 6 .
5. If scan tool 4WD low does not indicate ENABLED when circuit is grounded, check for open in Gray/Black wire. Repair as necessary, then go to next step. If wire is okay, check PCM/VCM connector for bent, backed out, deformed or damaged terminals. If terminals and connections are okay, replace PCM/VCM, then go to next step.
6. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Operate vehicle under following conditions. Select 4LO on selector switch. Drive vehicle in 4th gear with TCC on. Speed ratio must be 2.5-3.0 for 5 seconds. Select 4HI on selector switch. Drive vehicle in 4th gear with TCC on. Speed ratio must be .8-1.2 for 5 seconds. Select Specific DTC and enter DTC "P1875". If DTC P1875 is not present, repair is complete. If DTC P1875 is still present, repeat test.

Diagnostic Procedure (Active 4WD System)

Note. If PCM/VCM replacement is necessary, ensure new PCM/VCM is reprogrammed. See appropriate COMPUTER RELEARN PROCEDURES under GENERAL INFORMATION in ENGINE PERFORMANCE.

1. Connect scan tool to DLC. Turn ignition switch to ON position. Do not start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Set parking brake and block drive wheels. Shift transmission into Neutral. While observing scan tool 4WD low display, select 4HI on transfer case selector switch, then select 4LO on transfer case selector switch. If scan tool 4WD low does not display DISABLED when 4HI is selected and ENABLED when 4LO is selected, go to next step. If scan tool 4WD low displays DISABLED when 4HI is selected and ENABLED when 4LO is selected, see «DIAGNOSTIC AIDS (ALL MODELS)»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e__diagnostic-aids-all-models) .
3. Turn ignition off. Disconnect TCCM connector. See «TCCM LOCATION»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) table. Turn ignition switch to ON position. Connect test light between ground and Dark Green/White wire terminal at TCCM connector. Select 4LO, then 4HI on transfer case selector switch. If test light does not illuminate when 4LO is selected and illuminates when 4HI is selected, go to next step. If test light illuminates when 4LO low is selected and turns off when 4HI is selected, go to step 7 .
4. Connect test light between ground and Dark Green/White wire at transfer case selector switch. Select 4LO, then 4HI on selector switch. If test light does not illuminate when 4LO is selected and illuminates when 4HI is selected, go to next step. If test light illuminates when 4LO is selected and turns off when 4HI is selected, go to step 6 .
5. Connect test light between ground and Pink wire of transfer case selector switch. If test light illuminates, replace transfer case selector switch, then go to step 9 . If test light does not illuminate, check for open or short to ground in ignition feed circuit to transfer case selector switch. Repair circuit as necessary, then go to step 9 .
6. Check for open or short to ground in Dark Green/White wire between transfer case selector switch and TCCM. Repair as necessary, then go to step 9 .
7. Install a fused jumper between TCCM connector terminals (Dark Green/White wire and Gray/Black wire). If scan tool 4WD low displays ENABLED, replace TCCM, then go to step 9 . If scan tool 4WD low does not display ENABLED, turn ignition off. Reconnect TCCM connector. Disconnect appropriate PCM/VCM connector connected to 4WD low indicator signal circuit. See «WIRING DIAGRAMS»(/cadillac/escalade/gmt400-1998-2000/remont/automatic-trans/#automatic-transmission-diagnosis-4l60-e) . Connect test light between ground and 4WD low indicator signal circuit terminal at PCM/VCM connector. If test light illuminates, go to next step. If test light does not illuminate, check for open or short to ground in 4WD low indicator signal circuit. Repair circuit as necessary, then go to step 9 .
8. Check PCM/VCM connector for bent, backed out, deformed or damaged terminals. Repair as necessary, then go to next step. If terminals and connections are okay, replace PCM/VCM. Ensure PCM/VCM is reprogrammed. Go to next step.
9. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Operate vehicle under following conditions. Select 4LO on selector switch. Drive vehicle in 4th gear with TCC on. Speed ratio must be 2.5-3.0 for 5 seconds. Select 4HI on selector switch. Drive vehicle in 4th gear with TCC on. Speed ratio must be .8-1.2 for 5 seconds. Select Specific DTC and enter DTC "P1875". If DTC P1875 is not present, repair is complete. If DTC P1875 is still present, repeat test.

TCCM LOCATION

Diagnostic Aids (All Models)

Inspect wiring for poor connections at PCM/VCM. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

1999 Transmission Wiring Diagram - 3.8L Camaro & Firebird ("F" Body). Scheme 14

1998 Transmission Wiring Diagram - 5.7L Camaro & Firebird ("F" Body). Scheme 15

1999 Transmission Wiring Diagram - 5.7L Corvette ("Y" Body). Scheme 16

1999 Transmission Wiring Diagram - 4.3L, 5.0L & 5.7L Escalade, Pickup, Suburban, Tahoe & Yukon ("C" & "K" Series). Scheme 17

1999 Transmission Wiring Diagram - 4.3L, 5.0L & 5.7L Express, Savana & Van ("G" Series). Scheme 18

1999 Transmission Wiring Diagram - 4.3L Astro & Safari ("L" & "M" Series). Scheme 19

1999 Transmission Wiring Diagram - 2.2L Hombre, Pickup & Sonoma ("S" & "T" Series). Scheme 20

1999 Transmission Wiring Diagram - 4.3L Blazer, Bravada, Envoy, Hombre, Jimmy, Pickup & Sonoma ("S" & "T" Series). Scheme 21

See also:
• SHIFT SOLENOID OPERATION (4L60-E)
• CLEARING & RESETTING TAP VALUES
• LIMP-IN MODE
• DIAGNOSTIC AIDS
• ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (PASSENGER CARS)
• ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK (LIGHT TRUCKS & VANS)
• HARD OR INTERMITTENT TROUBLE CODE DETERMINATION
• NO MALFUNCTION INDICATOR LIGHT (MIL)
• NO DATA LINK CONNECTOR (DLC) DATA
• P0218
• P0502
• P0503
• P0711
• P0712
• P0713
• P0719
• P0724
• P0740
• P0742
• P0748
• P0751
• P0753
• P0756
• P0758
• P0785
• P1810
• P1860
• P1870
• P0218 (2.2L "S" Series)
• P0711
• P0724
• P1875
• CLEARING TROUBLE CODES
• DIAGNOSTIC TESTS (PASSENGER CARS)
• DIAGNOSTIC AIDS (ALL MODELS)