Possible Causes

PSCM Internal Failure DTCs
PSCM Network Lost Communications DTCs
PSCM Network Invalid Data DTCs
PSCM Voltage DTCs
Starter, alternator, charging system voltage levels low
Steering wiring harness, grounds or connectors
Non Steering wiring harness, grounds or connectors

CAUTION: Use the correct probe adatper(s) when taking measurements. Failure to use the correct probe adapter(s) may cause damage to the connector.

NOTE: Refer to Power Steering Controls in the appropriate OEM Wiring Diagrams article.

NOTE: Failure to disconnect the battery when instructed results in false resistance readings.

AG1: VERIFY BATTERY VOLTAGE LEVELS

Inspect the battery connections and battery wiring. Refer to appropriate Battery, Mounting and Cables article.
- Verify the connections are clean and tight.
- Verify the connections and cables are free from corrosion, cuts and other damage.
Inspect the generator connections and generator wiring. Refer to appropriate Generator and Regulator article.
- Verify the connections are clean and tight.
- Verify the connections and cables are free from corrosion, cuts, and other damage.
Verify the battery and charging system are providing the correct voltage to the vehicle.
Are the battery, generator and wiring in good condition, and is the system providing the correct voltage?

Yes	No
Go to AG2.	DIAGNOSE and REPAIR the battery or charging system. REFER to appropriate Battery and Charging System article. Go to AG2.

AG2: RETRIEVE THE PSCM DTCS

Ignition ON, engine OFF.
Clear the PSCM DTCs.
Drive the vehicle, attempt to replicate the customer's driving conditions.
Carry ou the PSCM self-test.
Does the PSCM respond to the diagnostic scan tool?

Yes	No
Go to AG3.	Go to Pinpoint Test A .

AG3: CHECK THE PSCM FOR INTERNAL FAULTS OR PROGRAMMING FAULTS

Ignition ON, engine OFF.
Carry out the PSCM self-test.
NOTE: This question does not apply to DTCs in history.
Are any of the following DTCs present in the PSCM; C102D, C1B00, C200C, C200D, P07AE, U2100, U2011, or U3000?

Yes	No
DIAGNOSE the PSCM DTCs. Go to the PSCM DTC Index .	Go to AG4.

AG4: CHECK THE PSCM FOR COMMUNICATION FAULTS OR INVALID DATA FAULTS

Using the results from the previous step, determine if any lost communication, invalid data or voltage DTCs are present in the PSCM.

Lost communication DTCs indicate the PSCM is missing messages from another module within a certain expected time frame.
Invalid data DTCs indicate the PSCM received messages from another module but the data in teh message is outside the expected content.
Voltage DTCs indicate the PSCM received voltages outside the expected range.

PSCM COMMUNICATION AND INVALID DATA DTCS

Lost Communication DTCs	Invalid Data DTCs	Voltage DTCs	Control Module DTCs
U0100	U0401	B1304	U3001
U0102	U0403	U3003
U0121	U0415
U0122	U0416
U0126	U0422
U0140	U0423
U0151	U0428
U0155	U0452
U0159	U045A
U019B	U053B
U0212	U053C
U023A	U0553
U023B	U0554
U0252

Are any of the DTCs from the above table either currently or previously present in the PSCM?

Yes	No
If any communication or invalid data DTCs are present without any voltage DTCs, Go to AG9. If ANY voltage DTCs are present, go to AG5.	Go to AG5.

AG5: CHECK THE PSCM FOR VOLTAGE FAULTS

Using the results from the previous step, determine if any voltage DTCs are present in the PSCM.
- These DTCs indicate the vehicle voltage levels delivered to PSCM were either interrupted, lower than the specific threshold range or higher than the specific threshold range the PSCM expects to receive.
Is DTC U3001 or U3003 either currently or previously present in the PSCM?

Yes	No
Go to AG6.	The PSCM circuit is working correctly at this time and is not a root cause of the ABS module C0051 DTC. Go to AG9.

AG6: PSCM CIRCUIT VERIFICATION - FUSES

NOTE: Refer to Power Steering Controls in the appropriate OEM Wiring Diagrams article and connector information

Are both fuses fully seated, undamaged and no open?

Yes	No
Go to AG7.	REINSTALL or INSTALL new fuses as necessary. Go to AG7.

AG7: PSCM CIRCUIT VERIFICATION - POWER WIRING AND CONNECTIONS

NOTE: Refer to Power Steering Controls in appropriate OEM Wiring Diagrams article for schematic and connector information.

Visually check both power wiring and ground wiring for chaffing or pinching on other components.
Verify the power and ground connections are clean, fully seated or tightened, and free of corrosion.
Are the power and ground and connections free from damage and correctly seated and tightened?

Yes	No
Go to AG8.	REPAIR or INSTALL new connectors or wiring as necessary. Go to AG8.

AG8: PSCM CIRCUIT VERIFICATION - POWER AND GROUND INTERNAL CIRCUIT CHECK

NOTE: This test verifies whether there is unseen, internal damage to the wiring harness.

Make sure the front wheels are on the ground and the vehicle is not being supported by other means.
- Make sure the front tires are clean and dry.
- Make sure the ground under the front tires is clean and dry.
Ignition ON, engine running.
Take the following measurement while turning the steering wheel back and forth, lock to lock, continuously at 1 revolution per second.

Measure the voltage between:

(+) Vehicle Battery	(-) Vehicle Battery
Positive terminal	Negative terminal

Access the PSCM and monitor the MOD_SUP_V (VOLT) PID.
Compare the measured battery voltage with the PID display.
Do the measured battery voltage and the PID display voltage differ by more than 1.5 volts?

Yes	No
INSTALL a new PSCM wiring harness. REPEAT this pinpoint test step to verify the new harness is also free from internal damage. If the voltage concerns are resolved, Go to AG11. If the communication concerns are still present, Go to AG9.	The PSCM power and ground circuits are working correctly at this time and are not root cause of the ABS module DTC C0051. If communication or invalid data DTCs are present in the PSCM, Go to AG9. If communication or invalid data DTCs are NOT present in the PSCM, Go to AG11.

AG9: PSCM CIRCUIT VERIFICATION - COMMUNICATION CONNECTIONS

NOTE: Refer to Power Steering Controls in appropriate OEM Wiring Diagrams article for schematic and connector information.

Ignition OFF.
PSCM_B connector disconnected. (C1463B)
Inspect all disconnected electrical connectors for the following:
- Pushed-out pins, loose pins, spread terminals, water ingress or corrosion.
- Missing or loose latches, broken or cracked connector housings.
Inspect the HS-CAN wiring for:
- Pinched or cut wiring under brackets, air cleaner boxes, battery trays, engine pulleys, etc.
- Loose wiring harness anchoring locations in the engine compartment.
Repair connectors or wiring as required.
PSCM_B connector connected. (C1463B) Make sure the connector seats and latches correctly.
Ignition ON, engine OFF.
Clear the PSCM DTCs.
Drive the vehicle, attempt to replicate the customer's driving conditions.
Carry out the PSCM self-test.
NOTE: This question does not apply to DTCs in history.
Are there any lost communication or invalid data DTCs currently present and active in the PSCM?

Yes	No
Go to AG10.	The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues. Go to AG11.

AG10: PSCM CIRCUIT VERIFICATION - COMMUNICATION WIRING

Ignition OFF.
Visually Inspect the HS-CAN wiring is not pinched, chaffed, chewed by animals, damaged near or under the battery tray or other nearby components.
Disconnect the battery negative cable. Refer to the General Procedure, Battery Disconnect in appropriate Battery, Mounting and Cables article.
DLC connector disconnected. (C251)
PSCM_B connector disconnected. (C1463B)

Measure the resistance between:

(+) PSCM_B (C1463B) Connector, Harness Side	(-) DLC (C251) Connector, Harness Side
CAN- - VDB05 (WHITE) - Pin 2	CAN- - VDB05 - Pin 14
CAN+ - VDB04 (WHITE/BLUE) - Pin 1	CAN+ - VDB04 - Pin 6

Is the resistance less than 3 ohms?

Yes	No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues. Go to AG11.	REPAIR the circuit. Go to AG11.

AG11: CHECK FOR ABS MODULE AND PSCM DTCS

Ignition ON, engine OFF.
Carry out the PSCM self-test.
Carry out the ABS self-test.
NOTE: This question does not apply to DTCs in history.
Are any lost communication or invalid data DTCs currently present and active in the PSCM or are any C0051 DTCs currently present and active in the ABS module?

Yes	No
The PSCM wiring harness circuit evaluation is complete and not contributing to the ABS module C0051 DTC. GO to the appropriate service information corresponding to the module name in the remaining lost communication or invalid data codes to continue the diagnostics.	The PSCM wiring harness circuit adjustments or repairs have resolved the lost communication, invalid data or ABS module C0051 DTC concerns with the PSCM.