Electronic Control Modules: Other Jeep Liberty I

STANDARD PROCEDURE - PCM/SKIM PROGRAMMING

Note. Before replacing the PCM for a failed driver, control circuit, or ground circuit, be sure to check the related component/circuit integrity for failures not detected due to a double fault in the circuit. Most PCM driver/control circuit failures are caused by internal component failures (i.e. relays and solenoids) and shorted circuits (i.e. pull-ups, drivers, and switched circuits). These failures are difficult to detect when a double fault has occurred and only one DTC has been set.

When a PCM (JTEC) and the Sentry Key Immobilizer Module (SKIM) are replaced at the same time, perform the following steps in order

1. Program the new PCM (JTEC).
2. Program the new SKIM.
3. Replace all ignition keys and program them to the new SKIM.

PROGRAMMING THE PCM (JTEC)

The SKIS Secret Key is an ID code that is unique to each SKIM. This code is programmed and stored in the SKIM, the PCM, and the ignition key transponder chip(s). When replacing the PCM, it is necessary to program the secret key into the new PCM using the DRBIII(R) scan tool. Perform the following steps to program the secret key into the PCM

1. Turn the ignition switch to the On position (transmission in Park/Neutral).
2. Use the DRBIII(R) and select THEFT ALARM, SKIM, then MISCELLANEOUS.
3. Select PCM REPLACED (GAS ENGINE).
4. Enter secured access mode by entering the vehicle four-digit PIN.
5. Select ENTER to update PCM VIN.
6. Press ENTER to transfer the secret key (the SKIM will send the secret key to the PCM).
7. Press PAGE BACK to get to the Select System menu and select ENGINE, MISCELLANEOUS, and SRI MEMORY CHECK.
8. The DRBIII(R) will ask, "Is odometer reading between XX and XX?" Select the YES or NO button on the DRBIII(R). If NO is selected, the DRBIII(R) will read, "Enter Odometer Reading (From I.P. odometer)". Enter the odometer reading from the instrument cluster and press ENTER.

PROGRAMMING THE SKIM

1. Turn the ignition switch to the On position (transmission in Park/Neutral).
2. Use the DRBIII(R) and select THEFT ALARM, SKIM, then MISCELLANEOUS.
3. Select PCM REPLACED (GAS ENGINE).
4. Program the vehicle four-digit PIN into SKIM.
5. Select COUNTRY CODE and enter the correct country.
6. Select YES to update VIN (the SKIM will learn the VIN from the PCM).
7. Press ENTER to transfer the secret key (the PCM will send the secret key to the SKIM).
8. Program ignition keys to the SKIM.

PROGRAMMING IGNITION KEYS TO THE SKIM

1. Turn the ignition switch to the On position (transmission in Park/Neutral).
2. Use the DRBIII(R) and select THEFT ALARM, SKIM, then MISCELLANEOUS.
3. Select PROGRAM IGNITION KEY'S.
4. Enter secured access mode by entering the vehicle four-digit PIN.
5. Obtain ignition keys to be programmed from the customer (8 keys maximum).
6. Using the DRBIII(R), erase all ignition keys by selecting MISCELLANEOUS, and ERASE ALL CURRENT IGN. KEYS.
7. Program all of the ignition keys.

If ignition key programming is unsuccessful, the DRBIII(R) will display one of the following messages

1. Programming Not Attempted - The DRBIII(R) attempts to read the programmed key status and there are no keys programmed into SKIM memory.
2. Programming Key Failed (Possible Used Key From Wrong Vehicle) - SKIM is unable to program an ignition key transponder due to one of the following: The ignition key transponder is faulty. The ignition key transponder is or has been already programmed to another vehicle.
3. 8 Keys Already Learned, Programming Not Done - The SKIM transponder ID memory is full.
4. Learned Key In Ignition - The ID for the ignition key transponder currently in the ignition lock cylinder is already programmed in SKIM memory.

Open Loop and Closed Loop.

During Open Loop modes, the PCM receives input signals and responds only according to preset PCM programming. Input from the oxygen (O2S) sensors is not monitored during Open Loop modes.

During Closed Loop modes, the PCM will monitor the oxygen (O2S) sensors input. This input indicates to the PCM whether or not the calculated injector pulse width results in the ideal air-fuel ratio. This ratio is 14.7 parts air-to-1 part fuel. By monitoring the exhaust oxygen content through the O2S sensor, the PCM can fine tune the injector pulse width. This is done to achieve optimum fuel economy combined with low emission engine performance.

The fuel injection system has the following modes of operation

1. Ignition switch ON
2. Engine Start-Up (Crank)
3. Engine Warm-Up
4. Idle
5. Cruise
6. Acceleration
7. Deceleration
8. Wide Open Throttle (WOT)
9. Ignition Switch OFF

The ignition switch On, engine start-up (crank), engine warm-up, acceleration, deceleration and wide open throttle modes are Open Loop modes. The idle and cruise modes, (with the engine at operating temperature) are Closed Loop modes.

IGNITION SWITCH (KEY-ON) MODE

This is an Open Loop mode. When the fuel system is activated by the ignition switch, the following actions occur

1. The PCM pre-positions the idle air control (IAC) motor.
2. The PCM determines atmospheric air pressure from the MAP sensor input to determine basic fuel strategy.
3. The PCM monitors the engine coolant temperature sensor input. The PCM modifies fuel strategy based on this input.
4. Intake manifold air temperature sensor input is monitored.
5. Throttle position sensor (TPS) is monitored.
6. The auto shutdown (ASD) relay is energized by the PCM for approximately three seconds.
7. The fuel pump is energized through the fuel pump relay by the PCM. The fuel pump will operate for approximately three seconds unless the engine is operating or the starter motor is engaged.
8. The O2S sensor heater element is energized via the ASD or O2S heater relay. The O2S sensor input is not used by the PCM to calibrate air-fuel ratio during this mode of operation.

ENGINE START-UP MODE

This is an Open Loop mode. The following actions occur when the starter motor is engaged.

The PCM receives inputs from

1. Battery Voltage
2. Engine Coolant Temperature Sensor
3. Crankshaft Position Sensor
4. Intake Manifold Air Temperature Sensor
5. Manifold Absolute Pressure (MAP) Sensor
6. Throttle Position Sensor (TPS)
7. Camshaft Position Sensor Signal

The PCM monitors the crankshaft position sensor. If the PCM does not receive a crankshaft position sensor signal within 3 seconds of cranking the engine, it will shut down the fuel injection system.

The fuel pump is activated by the PCM through the fuel pump relay.

Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then control the injection sequence and injector pulse width by turning the ground circuit to each individual injector on and off.

The PCM determines the proper ignition timing according to input received from the crankshaft position sensor.

ENGINE WARM-UP MODE

This is an Open Loop mode. During engine warm-up, the PCM receives inputs from

1. Battery Voltage
2. Crankshaft Position Sensor
3. Engine Coolant Temperature Sensor
4. Intake Manifold Air Temperature Sensor
5. Manifold Absolute Pressure (MAP) Sensor
6. Throttle Position Sensor (TPS)
7. Camshaft Position Sensor Signal
8. Park/Neutral Switch (Gear Indicator Signal - Auto. Trans. Only)
9. Air Conditioning Select Signal (If Equipped)
10. Air Conditioning Request Signal (If Equipped)

Based on these inputs the following occurs

1. Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then control the injection sequence and injector pulse width by turning the ground circuit to each individual injector on and off.
2. The PCM adjusts engine idle speed through the idle air control (IAC) motor and adjusts ignition timing.
3. The PCM operates the A/C compressor clutch through the A/C compressor clutch relay. This is done if A/C has been selected by the vehicle operator and specified pressures are met at the high and low-pressure A/C switches. Refer to Heating and Air Conditioning for additional information.
4. When engine has reached operating temperature, the PCM will begin monitoring O2S sensor input. The system will then leave the warm-up mode and go into closed loop operation.

IDLE MODE

When the engine is at operating temperature, this is a Closed Loop mode. At idle speed, the PCM receives inputs from

1. Air Conditioning Select Signal (If Equipped)
2. Air Conditioning Request Signal (If Equipped)
3. Battery Voltage
4. Crankshaft Position Sensor
5. Engine Coolant Temperature Sensor
6. Intake Manifold Air Temperature Sensor
7. Manifold Absolute Pressure (MAP) Sensor
8. Throttle Position Sensor (TPS)
9. Camshaft Position Sensor Signal
10. Battery Voltage
11. Park/Neutral Switch (Gear Indicator Signal-Auto. Trans. Only)
12. Oxygen Sensors

Based on these inputs, the following occurs

1. Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then control injection sequence and injector pulse width by turning the ground circuit to each individual injector on and off.
2. The PCM monitors the O2S sensor input and adjusts air-fuel ratio by varying injector pulse width. It also adjusts engine idle speed through the idle air control (IAC) motor.
3. The PCM adjusts ignition timing by increasing and decreasing spark advance.
4. The PCM operates the A/C compressor clutch through the A/C compressor clutch relay. This is done if A/C has been selected by the vehicle operator and specified pressures are met at the high and low-pressure A/C switches. See «MANUAL A/C-HEATER SYSTEMS»(ref-171996) .

CRUISE MODE

When the engine is at operating temperature, this is a Closed Loop mode. At cruising speed, the PCM receives inputs from

1. Air Conditioning Select Signal (If Equipped)
2. Air Conditioning Request Signal (If Equipped)
3. Battery Voltage
4. Engine Coolant Temperature Sensor
5. Crankshaft Position Sensor
6. Intake Manifold Air Temperature Sensor
7. Manifold Absolute Pressure (MAP) Sensor
8. Throttle Position Sensor (TPS)
9. Camshaft Position Sensor Signal
10. Park/Neutral Switch (Gear Indicator Signal-Auto. Trans. Only)
11. Oxygen (O2S) Sensors

Based on these inputs, the following occurs

1. Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then adjust the injector pulse width by turning the ground circuit to each individual injector on and off.
2. The PCM monitors the O2S sensor input and adjusts air-fuel ratio. It also adjusts engine idle speed through the idle air control (IAC) motor.
3. The PCM adjusts ignition timing by turning the ground path to the coil(s) on and off.
4. The PCM operates the A/C compressor clutch through the clutch relay. This happens if A/C has been selected by the vehicle operator and requested by the A/C thermostat.

ACCELERATION MODE

This is an Open Loop mode. The PCM recognizes an abrupt increase in throttle position or MAP pressure as a demand for increased engine output and vehicle acceleration. The PCM increases injector pulse width in response to increased throttle opening.

DECELERATION MODE

When the engine is at operating temperature, this is an Open Loop mode. During hard deceleration, the PCM receives the following inputs.

1. Air Conditioning Select Signal (If Equipped)
2. Air Conditioning Request Signal (If Equipped)
3. Battery Voltage
4. Engine Coolant Temperature Sensor
5. Crankshaft Position Sensor
6. Intake Manifold Air Temperature Sensor
7. Manifold Absolute Pressure (MAP) Sensor
8. Throttle Position Sensor (TPS)
9. Camshaft Position Sensor Signal
10. Park/Neutral Switch (Gear Indicator Signal-Auto. Trans. Only)
11. Vehicle Speed

If the vehicle is under hard deceleration with the proper RPM and closed throttle conditions, the PCM will ignore the oxygen sensor input signal. The PCM will enter a fuel cut-off strategy in which it will not supply a ground to the injectors. If a hard deceleration does not exist, the PCM will determine the proper injector pulse width and continue injection.

Based on the above inputs, the PCM will adjust engine idle speed through the idle air control (IAC) motor.

The PCM adjusts ignition timing by turning the ground path to the coil on and off.

WIDE OPEN THROTTLE MODE

This is an Open Loop mode. During wide open throttle operation, the PCM receives the following inputs.

1. Battery Voltage
2. Crankshaft Position Sensor
3. Engine Coolant Temperature Sensor
4. Intake Manifold Air Temperature Sensor
5. Manifold Absolute Pressure (MAP) Sensor
6. Throttle Position Sensor (TPS)
7. Camshaft Position Sensor Signal

During wide open throttle conditions, the following occurs

1. Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then control the injection sequence and injector pulse width by turning the ground circuit to each individual injector on and off. The PCM ignores the oxygen sensor input signal and provides a predetermined amount of additional fuel. This is done by adjusting injector pulse width.
2. The PCM adjusts ignition timing by turning the ground path to the coil(s) on and off.

IGNITION SWITCH OFF MODE

When ignition switch is turned to OFF position, the PCM stops operating the injectors, ignition coil, ASD relay and fuel pump relay.

CLUTCH VOLUME INDEX (CVI)

An important function of the TCM is to monitor Clutch Volume Index (CVI). CVI represent the volume of fluid needed to compress a clutch pack.

The TCM monitors gear ratio changes by monitoring the Input and Output Speed Sensors. The Input, or Turbine Speed Sensor sends an electrical signal to the TCM that represents input shaft RPM. The Output Speed Sensor provides the TCM with output shaft speed information.

By comparing the two inputs, the TCM can determine transmission gear position. This is important to the CVI calculation because the TCM determines CVI by monitoring how long it takes for a gear change to occur.

Scheme 14

Gear ratios can be determined by using the DRB(R) III Scan Tool and reading the Input/Output Speed Sensor values in the "Monitors" display. Gear ratio can be obtained by dividing the Input Speed Sensor value by the Output Speed Sensor value.

For example, if the input shaft is rotating at 1000 RPM and the output shaft is rotating at 500 RPM, then the TCM can determine that the gear ratio is 2:1. In direct drive (3rd gear), the gear ratio changes to 1:1. The gear ratio changes as clutches are applied and released. By monitoring the length of time it takes for the gear ratio to change following a shift request, the TCM can determine the volume of fluid used to apply or release a friction element.

The volume of transmission fluid needed to apply the friction elements are continuously updated for adaptive controls. As friction material wears, the volume of fluid need to apply the element increases.

Certain mechanical problems within the input clutch assembly (broken return springs, out of position snap rings, excessive clutch pack clearance, improper assembly, etc.) can cause inadequate or out-of-range element volumes. Also, defective Input/Output Speed Sensors and wiring can cause these conditions. The following chart identifies the appropriate clutch volumes and when they are monitored/updated

Scheme 15

SHIFT SCHEDULES

As mentioned earlier, the TCM has programming that allows it to select a variety of shift schedules. Shift schedule selection is dependent on the following

1. Shift Lever Position
2. Throttle Position
3. Engine Load
4. Fluid Temperature
5. Software Level

As driving conditions change, the TCM appropriately adjusts the shift schedule. Refer to the following table 42RLE Shift Schedule to determine the appropriate operation expected, depending on driving conditions.

Scheme 16

STANDARD PROCEDURE - TCM QUICK LEARN

The quick learn procedure requires the use of the DRB(R) scan tool.

This program allows the electronic transmission system to recalibrate itself. This will provide the proper transmission operation. The quick learn procedure should be performed if any of the following procedures are performed

1. Transmission Assembly Replacement
2. Transmission Control Module Replacement
3. Solenoid Pack Replacement
4. Clutch Plate and/or Seal Replacement
5. Valve Body Replacement or Recondition

To perform the Quick Learn Procedure, the following conditions must be met

1. The brakes must be applied.
2. The engine speed must be above 500 RPM.
3. The throttle angle (TPS) must be less than 3 degrees.
4. The shift lever position must stay in PARK until prompted to shift to overdrive.
5. The shift lever position must stay in overdrive after the Shift to Overdrive prompt until the DRB(R) indicates the procedure is complete.
6. The calculated oil temperature must be above 60° and below 200°.

RIGHT SEAT HEATER INOPERATIVE

Note. Any resistance values (ohms ohm) given in the following text are supplied using the automatic range generated by a Fluke(R) automotive meter. If another type of measuring device is used the values generated may not be the same as the results shown here, or may have to be converted to the range used here.

1. Remove the heated seat module from its mounting location. See «REMOVAL»(ref-175676-S06187126592005042600000) .
2. If a heated seat heats but one or both indicator lamps (LED's) on the heated seat switch fail to illuminate, check the driver circuit with the inoperative LED for a short to ground. If OK, replace the heated seat switch. If NOT OK repair the short to ground as required and than replace the heated seat switch.
3. Back-probe the heated seat module wire harness connector, do not disconnect. Check cavity #3 for battery voltage when the right heated seat switch is turned "ON", voltage should be present. If OK, go to next step. If not OK, test the right heated seat switch. See «DIAGNOSIS AND TESTING - PASSENGER HEATED SEAT»(ref-174945-S15635570272005041200000) in POWER & HEATED SEATS article. If the switch tests OK, check for continuity between the switch and control module on the MUX circuit, If OK replace the heated seat control module. If not OK, repair the open or shorted MUX circuit as required.
4. Back-probe the heated seat module wire harness connector, do not disconnect. Check cavity #10 for battery voltage, while observing the voltmeter depress the right heated seat switch Low setting twice. Voltage should toggle between approx.12v and 8v. If OK, go to next step. If NOT OK check for continuity between the switch and control module on the low heat driver circuit, If OK replace the heated seat control module.
5. Back-probe the heated seat module wire harness connector, do not disconnect. Check cavity #11 for battery voltage, while observing the voltmeter depress the right heated seat switch High setting twice. Voltage should toggle between approx.12v and 8v. If OK, go to next step. If NOT OK check for continuity between the switch and control module on the high heat driver circuit. If OK, replace the heated seat control module.
6. Back-probe the heated seat module wire harness connector, do not disconnect. Check cavity #2 for approx. 5v, voltage should be present. If OK go to next step. If NOT OK replace the heated seat control module.
7. Back-probe the heated seat module wire harness connector, do not disconnect. Check cavity #7 for a range in voltage from 1.72v (warm seat) - 3.0v (cold seat). It should be within this range. If OK, replace the heated seat module. If not OK, test the Heated Seat Sensor. If not OK, replace the right heated seat element and sensor assembly. If the heated seat sensor tests OK, check for continuity between the right heated seat cushion connector and control module connector on the 5v supply circuit. If not OK, repair the open or shorted 5v supply circuit as required. If OK check for continuity between the right heated seat cushion connector and control module connector on the temperature sensor input circuit. If not OK, repair the open or shorted temperature sensor input circuit as required. If OK replace the heated seat control module.

LEFT SEAT HEATER INOPERATIVE

1. If a heated seat heats but one or both indicator lamps (LED's) on the heated seat switch fail to illuminate, check the driver circuit with the inoperative LED for a short to ground. If OK, replace the heated seat switch. If not OK repair the short to ground as required and than replace the heated seat switch.
2. Back-probe the heated seat module wire harness connector, do not disconnect. Check cavity #5 for battery voltage when the left heated seat switch is turned "ON", voltage should be present. If OK, go to next step. If not OK, test the left heated seat switch. See «DIAGNOSIS AND TESTING - DRIVER HEATED SEAT SWITCH»(ref-174945-S40070986832005041200000) in POWER & HEATED SEATS article. If the switch tests OK, check for continuity between the switch and control module on the MUX circuit, If OK replace the heated seat control module. If not OK, repair the open or shorted MUX circuit as required.
3. Back-probe the heated seat module wire harness connector, do not disconnect. Check cavity #12 for battery voltage, while observing the voltmeter depress the left heated seat switch Low setting twice, voltage should toggle between approx.12v and 8v. If OK, go to next step. If not OK, check for continuity between the switch and control module on the low heat driver circuit. If OK, replace the heated seat control module.
4. Back-probe the heated seat module wire harness connector, do not disconnect. Check cavity #14 for battery voltage, while observing the voltmeter depress the left heated seat switch High setting twice, voltage should toggle between approx.12v and 8v. If OK, go to next step. If not OK, check for continuity between the switch and control module on the high heat driver circuit. If OK, replace the heated seat control module.
5. Back-probe the heated seat module wire harness connector, do not disconnect. Check cavity #2 for approx. 5v, 5 voltage should be present. If OK, go to next step. If not OK, replace the heated seat control module.
6. Back-probe the heated seat module wire harness connector, do not disconnect. Check cavity #8 for a range in voltage from 1.72v (warm seat) - 3.0v (cold seat). It should be within this range. If OK, replace the heated seat control module. If not OK, test the Heated Seat Sensor. If NOT OK, replace the left heated seat element and sensor assembly. If the heated seat sensor tests OK, check for continuity between the left heated seat cushion connector and control module connector on the 5v supply circuit. If not OK, repair the open or shorted 5v supply circuit as required. If OK, check for continuity between the left heated seat cushion connector and control module connector on the temperature sensor input circuit. If not OK, repair the open or shorted temperature sensor input circuit as required. If OK replace the heated seat control module.

BOTH SEATS INOPERATIVE

If both seats (driver and passenger) fail to heat and the indicator lamps on the heated seat switches for both seats fail to operate, test the heated seat fuses in the junction block. If the heated seat fuses check OK, go to step 1 .

1. Back-probe the heated seat module wire harness connector, do not disconnect. Check for continuity between the ground circuit cavity #13 of the heated seat module connector and a good ground. If OK, go to next step. If not OK, repair the open or shorted ground circuit as required.
2. Back-probe the heated seat module wire harness connector, do not disconnect. Check cavity #4 and #6 for battery voltage, voltage should be present. If OK, go to next step. If not OK, repair the open or shorted fused B(+) circuit as required.
3. Back-probe the heated seat module wire harness connector, do not disconnect. Check cavity #2 for approx. 5v, voltage should be present, replace the heated seat control module with a known good module and verify system operation.

Scheme 17

1. Working under the front seat cushion, remove the heated seat module from its mounting bracket by gently prying the module off of the two mounting pushpins.
2. Disconnect the seat wire harness connector from the connector receptacle on the side of the heated seat module.
3. Remove the heated seat module from the vehicle.