Diagnostic Starting Point - Automatic Transmission
Begin the system diagnosis with Diagnostic System Check - Vehicle in Vehicle DTC Information. The Diagnostic System Check provides the following information
- The identification of the control module(s) which commands the system
- The ability of the control module(s) to communicate through the serial data circuit
- The identification and status of stored diagnostic trouble codes (DTCs)
The use of Diagnostic System Check - Vehicle in Vehicle DTC Information identifies the correct procedure for diagnosing the system and where the procedure is located.
Symptoms
When it has been determined through Diagnostic System Check - Vehicle in Vehicle DTC Information that no DTCs are present, begin symptom diagnosis by reviewing the Transmission Component and System Description . Reviewing the Transmission Component and System Description information enables you to understand the operation of the system. This helps you determine if the condition described by the customer is normal or if a malfunction exists. If it is determined that a malfunction exists, identify the concern by referring to the Symptoms - Automatic Transmission table. The Symptoms - Automatic Transmission table provides common diagnostic categories which relate directly to diagnostic information or procedures.
Scan Tool Output Controls
| Scan Tool Output Control | Additional Menu Selection(s) | Description |
|---|---|---|
| 1-2 Solenoid | The PCM commands the 1-2 shift solenoid valve ON and OFF. The scan tool 1-2 Sol. parameter should match the commanded state. The scan tool Commanded Gear parameter should correspond with the shift solenoid combination. Refer to the Shift Solenoid Valve State and Gear Ratio table. When the ignition is ON and the engine is OFF, there are no limits to this control. The solenoid remains ON until commanded OFF and vice versa. When the output control is exited, the solenoid state is determined by the PCM. When the engine is running, the following control limits apply: Only sequential gear changes are allowed. For example, 1st to 3rd is not allowed. If a non-sequential gear change is attempted, the message "Non-sequential gear changes not allowed. Gear changes must be in order" appears on the scan tool display. The vehicle speed must be below a calibrated value. If the vehicle speed is too high, the message "Vehicle speed too high" appears on the scan tool display. The gear requested may not be greater than the current selected transmission range (PRNDL). For example, 3rd gear is not allowed if the transmission range is D2. If the gear requested is greater than the current selected transmission range, the message "Eng. running and gear request is greater than the current TR" appears on the scan tool display. The solenoid remains ON until commanded OFF and vice versa. When the output control is exited, the solenoid state is determined by the PCM. | |
| 2-3 Solenoid | The PCM commands the 2-3 shift solenoid valve ON and OFF. The scan tool 2-3 Sol. parameter should match the commanded state. The scan tool Commanded Gear parameter should correspond with the shift solenoid combination. Refer to the Shift Solenoid Valve State and Gear Ratio table. When the ignition is ON and the engine is OFF, there are no limits to this control. The solenoid will remain ON until commanded OFF and vice versa. When the output control is exited, the solenoid state is determined by the PCM. When the engine is running, the following control limits apply: Only sequential gear changes are allowed. For example, 1st to 3rd is not allowed. If a non-sequential gear change is attempted, the message "Non-sequential gear changes not allowed. Gear changes must be in order" appears on the scan tool display. The vehicle speed must be below a calibrated value. If the vehicle speed is too high, the message "Vehicle speed too high" appears on the scan tool display. The engine speed must be below a calibrated value. If the engine speed is too high, the message "Engine speed too high" appears on the scan tool display. Downshifts are allowed only when the vehicle speed is below a calibrated value. If the vehicle speed is too high, the message "Eng. is on and veh. speed too hi for 3-2 or 2-1 downshift" appears on the scan tool display. The gear requested may not be greater than the current selected transmission range (PRNDL). For example, 3rd gear is not allowed if the transmission range is D2. If the gear requested is greater than the current selected transmission range, the message "Eng. running and gear request is greater than the current TR" appears on the scan tool display. The solenoid remains ON until commanded OFF and vice versa. When the output control is exited, the solenoid state is determined by the PCM. | |
| Reset Transmission Adapts | The PCM clears or resets, the TAP cells to the original base value. There are no limits to using this output control. It may be performed with the engine running or when the ignition is ON and the engine is OFF. | |
| PC Solenoid | The PCM commands the amperage, current, to the pressure control solenoid valve in order to control transmission line pressure. As the amperage increases, the line pressure decreases. As the amperage decreases, the line pressure increases. The amperage range is 0.00-1.10 and may be commanded in one-tenth amp increments. When the ignition is ON and the engine is OFF, the reference, commanded, amperage may be controlled within calibrated limits. The scan tool parameter "PC Sol. Ref. Current" changes, but the parameter "PC Sol. Actual Current" does not change. The reference current remains until commanded otherwise. When the engine is running, the following control limits apply: When the transmission range is PARK or NEUTRAL, the reference, commanded, amperage may be controlled within calibrated limits. The engine speed must be less than 1,500 RPM. If the engine speed is greater than 1,500 RPM, the message "TR in park/neutral and engine speed over 1,500 RPM" appears on the scan tool display. Both the scan tool parameters "PC Sol. Ref. Current" and "PC Sol. Actual Current" change. Both current readings remain until commanded otherwise. When the transmission range is not in PARK or NEUTRAL, the reference amperage can only be controlled less than the current determined by the PCM. The PCM does not allow a value to be selected that may cause damage to the transmission. If the requested amperage is more than allowed by the PCM, the message "Requested current for the PC Solenoid is too high" appears on the scan tool display. Transmission range DTCs must not be active. If a transmission range DTC is active, the message "Engine running with transmission DTC present" appears on the scan tool display. | |
| Shift Transmission | The PCM commands upshifts and downshifts. The scan tool Commanded Gear parameter should correspond with the shift solenoid combination. Refer to the Shift Solenoid Valve State and Gear Ratio table. When the ignition is ON and the engine is OFF, there are no limits to this control. The scan tool shift solenoid states change to match the Current Gear selected. When the engine is running, the following control limits apply: The PCM does not allow a shift if it causes the engine RPM to exceed a calibrated limit. If a gear is requested and the engine speed is too high, the message "Engine speed too high" appears on the scan tool display. The PCM does not allow a 3-2 or 2-1 downshift if the vehicle speed exceeds a calibrated limit. If either downshift is requested and the vehicle speed is too high, the message "Eng. is on and veh. speed too hi for 3-2 or 2-1 downshift" appears on the scan tool display. The PCM does not allow a 4-3 downshift if the vehicle speed exceeds a calibrated limit. If a 4-3 downshift is requested and the vehicle speed is too high, the message "Vehicle speed too high" appears on the scan tool display. The PCM does not allow an upshift if the vehicle speed exceeds a calibrated limit. If an upshift is requested and the vehicle speed is too high, the message "Vehicle speed too high" appears on the scan tool display. The PCM does not allow an upshift that is greater than the current selected transmission range (PRNDL). For example, 3rd gear is not allowed if the transmission range is D2. If an upshift is requested that is greater than the current selected transmission range, the message "Eng. running and gear request is greater than the current TR" appears on the scan tool display. | |
| TCC Control Solenoid | The PCM commands the duty cycle of the TCC PWM solenoid valve. The duty cycle is represented by a percentage of ON energized time. Approximately 90-100 percent duty cycle represents an ON energized commanded state. Zero percent represents an OFF non-energized commanded state. The scan tool TCC Duty Cycle parameter should match the commanded state. When the ignition is ON and the engine is OFF, there are no limits to this control. The solenoid remains ON, 90-100 percent duty cycle until commanded OFF, zero percent duty cycle and vice versa. When the output control is exited, the solenoid duty cycle is determined by the PCM. When the engine is running, the following control limits apply: If the transmission range is PARK and the transmission is in hot mode, the TCC PWM solenoid valve may not be commanded OFF. If the solenoid is requested OFF, the message "TCC OFF command disabled in Hot Mode" appears on the scan tool display. The TCC PWM solenoid valve may not be commanded OFF for more than a calibrated amount of time. If the solenoid is commanded OFF, for a certain amount of time, the message "TCC OFF time has been exceeded" appears on the scan tool display. |
Scan Tool Output Controls
Scan Tool Data List (3.6L)
Use the scan tool data list under the following conditions
- The Diagnostic System Check is complete.
- The on-board diagnostics are functioning properly.
- No DTCs are present.
The values below represent a typical display recorded from a properly functioning system.
| IMPORTANT | Do not use a scan tool that displays faulty data. Report the condition to the scan tool manufacturer. The use of a faulty scan tool can result in misdiagnosis and the unnecessary replacement of parts. |
Only the parameters listed below are used in this article for diagnosing. If a scan tool displays other parameters, the values are not recommended by General Motors for use in diagnosis.
Scan tool values below were recorded under the following conditions
- Engine at Idle
- Upper radiator hose hot
- Closed throttle
- Transmission in PARK
- Closed Loop operation
- Accessories OFF
- Brake pedal not applied
| Scan Tool Parameter | Data List | Units Displayed | Typical Data Value |
|---|---|---|---|
| 1-2 Shift Error | F2, F6/F0 | Seconds | Varies |
| 1-2 Shift Time | F0, F2, F6/F0 | Seconds | Varies |
| 1-2 Sol. | F0, F2, F3, F4 | On/Off | On |
| 1-2 Sol. CKT Status | F2 | OK, Open/Short to GND, Short to Volts | OK |
| 1-2 TAP Cell (4-16) | F6/F0 | KPa/psi | Each cell varies |
| 2-3 Shift Error | F3, F6/F1 | Seconds | Varies |
| 2-3 Shift Time | F0, F3, F6/F1 | Seconds | Varies |
| 2-3 Sol. | F0, F2, F3, F4 | On/Off | On |
| 2-3 Sol. CKT Status | F3 | OK, Open/Short to GND, Short to Volts | OK |
| 2-3 TAP Cell (4-16) | F6/F1 | KPa/psi | Each cell varies |
| 3-4 Shift Error | F4, F6/F2 | Seconds | Varies |
| 3-4 Shift Time | F0, F4, F6/F2 | Seconds | Varies |
| 3-4 TAP Cell (4-16) | F6/F2 | KPa/psi | Each cell varies |
| Calc. Throttle Position | F0, F1, F2, F3, F4, F5 | % | 0 |
| Commanded Gear | F0, F1, F2, F3, F4, F5 | 1,2,3,4 | 1 |
| Current TAP Cell | F6/F0, F6/F1, F6/F2 | 4-16 | Varies |
| ECT | F0, F1 | °C (°F) | Varies |
| Engine Speed | F0, F1, F2, F3, F4, F5 | RPM | 600-850 RPM |
| Engine Torque | F0, F1 | N.m (lb ft) | Varies |
| Gear Ratio | F0, F1, F2, F3, F4 | Ratio | 3.98 |
| Ignition Voltage | F0 | Volts | 12.5-14.5 Volts |
| IMS | F0 | Park, Park/Reverse, Reverse, Reverse/Neutral, Neutral, Neutral/Drive 4, Drive 4, Drive 4/Drive 3, Drive 3, Drive 3/Drive 2, Drive 2, Drive 2/Drive 1, Drive 1, Invalid, Open | Park |
| IMS A/B/C/P | F0 | HI/LOW | LOW/HI/HI/LOW |
| Last Shift Time | F0 | Seconds | Varies |
| PC Sol. Actual Current | F0, F5 | Amps | 0.95-1.05 |
| PC Sol. Duty Cycle | F0, F5 | Percent | 45-55% |
| PC Sol. Ref. Current | F0, F5 | Amps | 0.95-1.05 |
| Steady State TAP 1GR | F6/F3 | KPa/psi | Varies |
| Steady State TAP 2GR | F6/F3 | KPa/psi | Varies |
| Steady State TAP 2GR/TCC | F6/F3 | KPa/psi | Varies |
| Steady State TAP 3GR | F6/F3 | KPa/psi | Varies |
| Steady State TAP 3GR/TCC | F6/F3 | KPa/psi | Varies |
| Steady State TAP 4GR | F6/F3 | KPa/psi | Varies |
| Steady State TAP 4GR/TCC | F6/F3 | KPa/psi | Varies |
| Steady State TAP Reverse | F6/F3 | KPa/psi | Varies |
| TCC Brake Switch | F0, F1 | Open/Closed | Closed |
| TCC Duty Cycle | F0, F1 | Percent | 0% |
| TCC Duty Cycle CKT Status | F1 | OK, Open/Short to GND, Short to Volts | OK |
| TCC Release Pressure | F0, F1 | Yes/No | Yes |
| TCC Slip Speed | F0, F1 | RPM | Varies |
| Traction Control | F0 | Active/Inactive | Inactive |
| Trans. Fluid Temp. | F0, F1, F5 | °C (°F) | Varies |
| Transmission Hot Mode | F0, F1 | On/Off | Off |
| Transmission ISS | F0, F1, F2, F3, F4 | RPM | 650-800 RPM |
| Transmission OSS | F0, F1, F2, F3, F4 | RPM | 0 RPM |
| Vehicle Speed | F0, F1, F2, F3, F4 | Km/h (mph) | 0 km/h |
| Data List Legend F0: Transmission Data F1: TCC Data F2: 1-2 Shift Data F3: 2-3 Shift Data F4: 3-4 Shift Data F5: PC Solenoid Data F6: Transmission Adapts F6/F0: 1-2 Adapt. Data F6/F1: 2-3 Adapt. Data F6/F2: 3-4 Adapt. Data F6/F3: Steady State Data | |||
Transmission Scan Tool Data List
Scan Tool Data List (3.8L)
Use the scan tool data list under the following conditions
- The Diagnostic System Check is complete.
- The on-board diagnostics are functioning properly.
- No DTCs are present.
The values below represent a typical display recorded from a properly functioning system.
| IMPORTANT | Do not use a scan tool that displays faulty data. Report the condition to the scan tool manufacturer. The use of a faulty scan tool can result in misdiagnosis and the unnecessary replacement of parts. |
Only the parameters listed below are used in this article for diagnosing. If a scan tool displays other parameters, the values are not recommended by General Motors for use in diagnosis.
Scan tool values below were recorded under the following conditions
- Engine at Idle
- Upper radiator hose hot
- Closed throttle
- Transmission in PARK
- Closed Loop operation
- Accessories OFF
- Brake pedal not applied
| Scan Tool Parameter | Data List | Units Displayed | Typical Data Value |
|---|---|---|---|
| 1-2 Shift Error | F2, F6/F0 | Seconds | Varies |
| 1-2 Shift Time | F0, F2, F6/F0 | Seconds | Varies |
| 1-2 Sol. | F0, F2, F3, F4 | On/Off | On |
| 1-2 Sol. CKT Status | F2 | OK, Open/Short to GND, Short to Volts | No |
| 1-2 TAP Cell (4-16) | F6/F0 | KPa/psi | Each cell varies |
| 2-3 Shift Error | F3, F6/F1 | Seconds | Varies |
| 2-3 Shift Time | F0, F3, F6/F1 | Seconds | Varies |
| 2-3 Sol. | F0, F2, F3, F4 | On/Off | On |
| 2-3 Sol. CKT Status | F3 | OK, Open/Short to GND, Short to Volts | No |
| 2-3 TAP Cell (4-16) | F6/F1 | KPa/psi | Each cell varies |
| 3-4 Shift Error | F4, F6/F2 | Seconds | Varies |
| 3-4 Shift Time | F0, F4, F6/F2 | Seconds | Varies |
| 3-4 TAP Cell (4-16) | F6/F2 | KPa/psi | Each cell varies |
| A/C Clutch Feedback Signal | F0 | On/Off | Off |
| Commanded Gear | F0, F1, F2, F3, F4, F5 | 1,2,3,4 | 1 |
| Cruise | F0 | Enabled/Disabled | Disabled |
| Current TAP Cell | F6/F0, F6/F1, F6/F2 | 4-16 | Varies |
| ECT Sensor | F0, F1 | °C (°F) | Varies |
| Engine Run Time | F0 | Hours/minutes/seconds | Varies |
| Engine Speed | F0, F1, F2, F3, F4, F5 | RPM | 600-850 RPM |
| Engine Torque | F0, F1 | N.m (lb ft) | Varies |
| Gear Ratio | F0, F1, F2, F3, F4 | Ratio | 3.98 |
| Ignition Voltage | F0 | Volts | 12.5-14.5 Volts |
| IMS | F0 | Park, Park/Reverse, Reverse, Reverse/Neutral, Neutral, Neutral/Drive 4, Drive 4, Drive 4/Drive 3, Drive 3, Drive 3/Drive 2, Drive 2, Drive 2/Drive 1, Drive 1, Invalid, Open | Park |
| IMS A/B/C/P | F0 | HI/LOW | LOW/HI/HI/LOW |
| Last Shift Time | F0 | Seconds | Varies |
| PC Sol. Actual Current | F0, F5 | Amps | 0.95-1.05 |
| PC Sol. Duty Cycle | F0, F5 | Percent | 45-55% |
| PC Sol. Ref. Current | F0, F5 | Amps | 0.95-1.05 |
| Steady State TAP 1GR | F6/F3 | KPa/psi | Varies |
| Steady State TAP 2GR | F6/F3 | KPa/psi | Varies |
| Steady State TAP 2GR/TCC | F6/F3 | KPa/psi | Varies |
| Steady State TAP 3GR | F6/F3 | KPa/psi | Varies |
| Steady State TAP 3GR/TCC | F6/F3 | KPa/psi | Varies |
| Steady State TAP 4GR | F6/F3 | KPa/psi | Varies |
| Steady State TAP 4GR/TCC | F6/F3 | KPa/psi | Varies |
| Steady State TAP Reverse | F6/F3 | KPa/psi | Varies |
| TCC Brake Switch | F0, F1 | Open/Closed | Closed |
| TCC Duty Cycle | F0, F1 | Percent | 0% |
| TCC Duty Cycle CKT Status | F1 | OK, Open/Short to GND, Short to Volts | No |
| TCC Release Pressure | F0, F1 | Yes/No | Yes |
| TCC Slip Speed | F0, F1 | RPM | Varies |
| TFT Sensor | F0, F1, F5 | Volts | Varies |
| TP Indicated Angle | F0, F1, F2, F3, F4, F5 | Percent | 0% |
| Traction Control Signal | F0 | Active/Inactive | Inactive |
| Trans. Fluid Temp. | F0, F1, F5 | °C (°F) | Varies |
| Transmission Hot Mode | F0, F1 | On/Off | Off |
| Transmission ISS | F0, F1, F2, F3, F4 | RPM | 700-800 RPM |
| Transmission OSS | F0, F1, F2, F3, F4 | RPM | 0 RPM |
| Vehicle Speed | F0, F1, F2, F3, F4 | Km/h (mph) | 0 km/h |
| Data List Legend F0: Transmission Data F1: TCC Data F2: 1-2 Shift Data F3: 2-3 Shift Data F4: 3-4 Shift Data F5: PC Solenoid Data F6: Transmission Adapts F6/F0: 1-2 Adapt. Data F6/F1: 2-3 Adapt. Data F6/F2: 3-4 Adapt. Data F6/F3: Steady State Data | |||
Transmission Scan Tool Data List
Diagnostic Trouble Code (DTC) Type Definitions
The DTC Type Definitions contain the characteristics for all types of DTCs. Each DTC type may or may not be found in this article. The DTC type is based on the action that the PCM takes when storing DTC information and whether or not the PCM illuminates a service lamp or displays a message on a driver information center (DIC). The DTC descriptions in the Diagnostic Trouble Code List/Type are listed in numeric order and indicate the DTC types for domestic and export vehicle applications. Each DTC is categorized into one of the following types
The service information contained in this article refers to the domestic federal calibration package. Domestic calibrations apply to vehicles sold in the United States, Canada and Japan. Export calibrations exist for both leaded and unleaded vehicles. DTC types may change for some export vehicles and some DTCs may be turned off for leaded export vehicles. Differences between domestic and export calibrations are not reflected on DTC support information. DTC types for export calibrations are referenced only in the Diagnostic Trouble Code (DTC) List/Type .
Diagnostic Trouble Code (DTC) List/Type
Diagnostic Trouble Code (DTC) List/Type
See also:
• Diagnostic System Check - Vehicle
• Transmission Component and System Description
• Symptoms - Automatic Transmission
• Shift Solenoid Valve State and Gear Ratio
• DTC P0218 (3.6L)
• DTC P0572
• DTC P0703
• DTC P0716 (3.8L)
• DTC P0751 (3.6L)
• DTC P1823 (3.6L)
• DTC U0100-U0299
• Diagnostic Trouble Code (DTC) List/Type