Pinpoint Test P: Transmission Four Wheel Drive (4X4) Mode Select Switch Failure

Four Wheel Drive (4WD) Systems - Electronic Shift







Pinpoint Test P: Transmission Four Wheel Drive (4X4) Mode Select Switch Failure

Normal Operation

The Mode Select Switch (MSS) communicates the operator's choice to the 4X4 control module. The 4X4 control module controls the shift solenoid, transfer case motor and Pulse Vacuum Hublock (PVH) as necessary. If the vehicle is not responding to the operator's intentions, systematically check the necessary inputs and outputs of the MSS and the 4X4 control module. Check all circuits for opens and shorts to power or ground.

- DTC P1812 (4-Wheel Drive Mode Select Circuit Failure) - Fault sets when 4X4 control module senses an open circuit. Four-Wheel Drive (4WD) system mode cannot be changed.
- DTC P1815 (4-Wheel Drive Mode Select Short To Ground) - Fault sets when 4X4 control module detects a short to ground. 4WD system mode cannot be changed.

This pinpoint test is intended to diagnose the following:
- MSS
- Circuitry
- 4X4 control module



PINPOINT TEST P: TRANSMISSION FOUR WHEEL DRIVE (4X4) MSS FAILURE

-------------------------------------------------
P1 CHECK THE MSS PIDs


- Connect the scan tool.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: DataLogger - 4WD Module.
- Monitor each 4WD_SW PID while cycling through each MSS position.
- Does each MSS PID agree with each switch position?

Yes
No problem found. CLEAR the DTCs. GO to Pinpoint Test O. Pinpoint Test O: Electronic Shift-On-The-Fly (ESOF) Functional Test

No
GO to P2.

-------------------------------------------------
P2 CHECK MSS RESISTANCE VALUES


- Ignition OFF.
- Disconnect: MSS C284.
- Measure the resistance between MSS C284, terminals 2 and 3, component side, while rotating the switch through all positions. Refer to the following chart:









- Are the resistance values within specification?

Yes
GO to P3.

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

-------------------------------------------------
P3 CHECK MSS CIRCUITS CCF13 (WH/BU) AND RCF13 (WH/BN) FOR A SHORT TO GROUND


- Ignition OFF.
- Disconnect: 4X4 Control Module C281A.
- Disconnect: MSS C284.
- Measure the resistance between MSS C284-2, circuit CCF13 (WH/BU) harness side and ground.
- Measure the resistance between MSS C284-3, circuit RCF13 (WH/BN) harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to P4.

No
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test.

-------------------------------------------------
P4 CHECK MSS CIRCUITS CCF13 (WH/BU) AND RCF13 (WH/BN) FOR AN OPEN


- Measure the resistance between MSS C284-2, circuit CCF13 (WH/BU) and 4X4 control module C281A-9, circuit CCF13 (WH/BU), harness side.




- Measure the resistance between MSS C284-3, RCF13 (WH/BN) and 4X4 control module C281A-2, circuit RCF13 (WH/BN), harness side.




- Are the resistances less than 5 ohms?

Yes
GO to P5.

No
REPAIR the affected circuit(s). CONNECT the 4X4 control module. CLEAR the DTCs. REPEAT the self-test.

-------------------------------------------------
P5 CHECK MSS CIRCUITS CCF13 (WH/BU) AND RCF13 (WH/BN) FOR A SHORT TOGETHER


- Ignition OFF.
- Measure the resistance between MSS C284-2, circuit CCF13 (WH/BU) harness side and C284-3, circuit RCF13 (WH/BN).




- Is the resistance greater than 10,000 ohms?

Yes
GO to P6.

No
REPAIR the affected circuit(s). CLEAR the DTC. REPEAT the self-test.

-------------------------------------------------
P6 CHECK MSS CIRCUITS CCF13 (WH/BU) AND RCF13 (WH/BN) FOR A SHORT TO VOLTAGE


- Ignition ON.
- Measure the voltage between MSS C284-2, circuit CCF13 (WH/BU) harness side and ground.
- Measure the voltage between MSS C284-3, circuit RCF13 (WH/BN) harness side and ground.




- Is any voltage present?

Yes
REPAIR the affected circuit(s). CLEAR the DTC. REPEAT the self-test.

No
GO to P7.

-------------------------------------------------
P7 CHECK MSS CIRCUIT RCF13 (WH/BN) FOR REFERENCE VOLTAGE


- Ignition OFF.
- Connect: 4X4 Control Module C281A.
- Ignition ON.
- Measure the voltage between MSS C284-3, circuit RCF13 (WH/BN) harness side and ground.




- Is a +5-volt reference present (not battery voltage)?

Yes
No problem found. The condition may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.

No
INSTALL a new 4X4 control module. REFER to 4X4 Control Module Service and Repair. TEST the system for normal operation.

-------------------------------------------------