TG: 4x4 Low (4x4L) Range

TG: Introduction See: TG: 4x4 Low (4x4L) Range - Introduction

TG1 VERIFY 4x4L SELECTOR POSITION

DTC P1729, P1781
Note: The transmission range (TR) sensor must indicate NEUTRAL position before 4x4L shift.

• Verify vehicle is equipped with 4x4.
• Verify selector is in 4x2 or 4x4H.

Is the selector in 2WD or 4x4H mode during Quick Test ?
Yes

• GO to TG2

.

No

• VERIFY transmission

shift lever is in neutral position. SELECT 2WD or 4x4H. Rerun Quick Test.

TG2 CHECK 4x4L CIRCUIT FOR INTERMITTENT FAULT

• Connect scan tool.
• Key on, engine off.
• Access 4x4L PID.
• Cycle the 4x4L switch to 2WD.
• Grasp the vehicle harness starting at the transfer case vehicle harness connector. Shake and bend a small section of the harness all the way to the PCM.
• Tap the vehicle harness connector at the transfer case.
• Shake and bend a small section of the harness between the Instrument Cluster Connector and the PCM.
• Key off.

Did the 4x4L PID reading go ON/OFF during harness and connector movement?
Yes

• ISOLATE fault and REPAIR as necessary.

No

• GO to TG3

.

TG3 CHECK 4X4L SIGNAL VOLTAGE TO PCM

• Disconnect PCM.
• Key on, engine off.
• Observe voltage between 4x4L circuit at PCM harness connector and battery negative post while cycling the switch.
• Key off.

Did the voltage cycle?
Yes

• REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM).

No

• GO to TG4

.

TG4 CHECK 4X4L CIRCUIT FOR OPEN IN HARNESS

• Disconnect the electronic shift control module.
• Measure resistance of 4x4L circuit between PCM harness connector pin and 4x4L switch harness connector pin.

Is the resistance less than 5.0 ohms?
Yes

• GO to TG5

.

No

• REPAIR open circuit.

TG5 CHECK 4x4L CIRCUIT FOR SHORT TO POWER OR GROUND IN HARNESS

• Connect electronic shift control module.
• Measure resistance between 4x4L circuit at PCM harness connector pin and battery negative post.
• Measure resistance between 4x4L and VPWR circuits at PCM harness connector.

Are both resistances greater than 10,000 ohms?
Yes

• REFER to the Transfer Case, Section "Four Wheel Drive Systems.

No

• REPAIR short circuit.