P189A

Electronic Locking Differential (ELD) System

Pinpoint Test S: DTC P189A:00



Normal Operation

When the Mode Select Switch (MSS) is engaged to lock the rear differential, a Pulse Width Modulated (PWM) signal is sent to the Electronic Locking Differential (ELD) field coil by the Transfer Case Control Module (TCCM) through the differential lock control circuit. This signal is a PWM (Pulse Width Modulated) signal which is initially 98% duty cycle to lock the differential and decreases to 40% duty cycle once the differential is locked. When the differential is starting to lock, the graphic in the Instrument Panel Cluster (IPC) message center starts to blink. When the differential is fully locked, the graphic illuminates steady.

- DTC P189A:00 (Axle Disconnect Input Switch Circuit Low: No Sub Type Information)- When not in locking mode, the TCCM (Transfer Case Control Module) senses the resistance to ground on circuit CCF32 and if the differential is always engaged. This DTC only displays during the self-test function.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- MSS (Mode Select Switch)

- TCCM (Transfer Case Control Module)

PINPOINT TEST S : DTC P189A:00

NOTE: Make sure the battery is fully charged before carrying out this pinpoint test.

S1 CHECK THE MSS (Mode Select Switch)

- Ignition OFF.

- Disconnect: MSS (Mode Select Switch) C284.

- Set the Mode Select Switch (MSS) in 2H (Electronic Shift-On-The-Fly (ESOF).

- Set the Mode Select Switch (MSS) in OFF (2-Wheel Drive (2WD) or MSOS (Manual Shift-On-Stop) ).

- Measure the resistance between MSS (Mode Select Switch) C284 pins 1 and 2, component side, while the MSS (Mode Select Switch) is in 2H or OFF position.





Are the resistance values between 22-27 ohms?

Yes
GO to S2.

No
INSTALL a new MSS (Mode Select Switch). REFER to Mode Select Switch (MSS) . CLEAR the DTCs. TEST the system for normal operation. REPEAT the self-test.

S2 CHECK THE ELD (Electronic Locking Differential) MODE CIRCUIT FOR A SHORT TO GROUND

- Ignition OFF.

- Disconnect: TCCM (Transfer Case Control Module) C2371A.

- Measure the resistance between TCCM (Transfer Case Control Module) C2371A-15, circuit CCF32 (WH/GN), harness side and ground.





Is the resistance greater than 10,000 ohms?

Yes
GO to S3.

No
REPAIR circuit CCF32 (WH/GN). CLEAR the DTCs. TEST the system for normal operation. REPEAT the self-test.

S3 CHECK FOR CORRECT TCCM (Transfer Case Control Module) OPERATION

- Ignition OFF.

- Disconnect all TCCM (Transfer Case Control Module) connectors.

- Check for:
- corrosion

- pushed-out pins


- Connect all TCCM (Transfer Case Control Module) connectors and make sure they are seated correctly.

- Operate the system and verify the concern is still present.

Is the concern still present?

Yes
INSTALL a new TCCM (Transfer Case Control Module). REFER to Transfer Case Control Module (TCCM) . TEST the system for normal operation. REPEAT the self-test.

No
The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector. CLEAR the DTCs. TEST the system for normal operation. REPEAT the self-test.