Diagnostic Procedure

DTC U0401:68 [VEHICLE CONTROL MODULE (US)] DIAGNOSTIC PROCEDURE

Step	Inspection	Results	Action
1	INSPECT VEHICLE CONTROL MODULE (VCM) AND BODY CONTROL MODULE (BCM) FOR MALFUNCTION Perform the DTC inspection for the vehicle control module (VCM) and the body control module (BCM). (See DTC INSPECTION .) Is a DTC related to an internal malfunction displayed?	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting. (See DTC TABLE [VEHICLE CONTROL MODULE (US)] .) (See DTC TABLE [BODY CONTROL MODULE (BCM) (US)] .)
1		No	Go to the next step.
2	INSPECT PCM FOR MALFUNCTION Perform the DTC inspection for the PCM. (See DTC INSPECTION .) Is a DTC displayed?	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting. (See DTC TABLE [PCM (VINs 7, L, M) (US)] .) (See DTC TABLE [PCM (VIN Y)] .)
2		No	Go to the next step.
3	INSPECT DSC HU/CM FOR MALFUNCTION Perform the DTC inspection for the DSC HU/CM. (See DTC INSPECTION .) Is a DTC displayed?	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting. (See DTC TABLE [DSC HU/CM (US)] .)
3		No	Go to the next step.
4	INSPECT INSTRUMENT CLUSTER FOR MALFUNCTION Perform the DTC inspection for the instrument cluster. (See DTC INSPECTION .) Is a DTC displayed?	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting. (See DTC TABLE [BODY CONTROL MODULE (BCM) (US)] .)
4		No	Go to the next step.
5	INSPECT BODY CONTROL MODULE (BCM) FOR MALFUNCTION Perform the DTC inspection for the body control module (BCM). (See DTC INSPECTION .) Is a DTC displayed?	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting. (See DTC TABLE [BODY CONTROL MODULE (BCM) (US)] .)
5		No	Go to the next step.
6	INSPECT CRUISE CONTROL SWITCH FOR MALFUNCTION Inspect the cruise control switch for a malfunction. (See CRUISE CONTROL SWITCH INSPECTION .) Is the cruise control switch normal?	Yes	Replace the cruise control switch and perform the repair completion verification. (See CRUISE CONTROL SWITCH REMOVAL/INSTALLATION .)
6		No	Go to the next step.
7	INSPECT PCM FOR MALFUNCTION DEPENDING ON REPEATABILITY Install/connect the part removed/disconnected during the troubleshooting procedure. Clear the DTC recorded in the memory. (See CLEARING DTC .) Operate the brake pedal. Perform the DTC inspection for the vehicle control module (VCM). (See DTC INSPECTION .) Is the same Pending DTC present?	Yes	Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error. (See CONTROLLER AREA NETWORK (CAN) MALFUNCTION DIAGNOSIS FLOW (US) .) If the CAN communication is normal, replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION [(VIN M) (US)] .) (See PCM REMOVAL/INSTALLATION [(VIN 7 & VIN L) (US)] .) (See PCM REMOVAL/INSTALLATION [(VIN Y) (US)] .)
7		No	Go to repair completion verification 2.
8	INSPECT DSC HU/CM FOR MALFUNCTION DEPENDING ON REPEATABILITY Install/connect the part removed/disconnected during the troubleshooting procedure. Clear the DTC recorded in the memory. (See CLEARING DTC .) Operate the brake pedal. Perform the DTC inspection for the vehicle control module (VCM). (See DTC INSPECTION .) Is the same Pending DTC present?	Yes	Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error. (See CONTROLLER AREA NETWORK (CAN) MALFUNCTION DIAGNOSIS FLOW (US) .) If the CAN communication is normal, replace the DSC HU/CM and perform the repair completion verification. (See DSC HU/CM REMOVAL/INSTALLATION [L.H.D. (US)] .)
8		No	Go to repair completion verification 2.
Repair completion verification 1	VERIFY THAT VEHICLE IS REPAIRED Install/connect the part removed/disconnected during the troubleshooting procedure. Clear the DTC recorded in the memory. (See CLEARING DTC .) Operate the brake pedal. Perform the DTC inspection for the vehicle control module (VCM). (See DTC INSPECTION .) Is the same Pending DTC present?	Yes	Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error. (See CONTROLLER AREA NETWORK (CAN) MALFUNCTION DIAGNOSIS FLOW (US) .) If the CAN communication is normal, perform the diagnosis from Step 1. If the malfunction recurs, replace the body control module (BCM), then go to the next step. (See BODY CONTROL MODULE (BCM) REMOVAL/INSTALLATION .)
Repair completion verification 1		No	Go to the next step.
Repair completion verification 2	VERIFY IF OTHER DTC IS DISPLAYED Perform the DTC inspection. (See DTC INSPECTION .) Are any other DTCs displayed?	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting.
Repair completion verification 2		No	DTC troubleshooting completed.