Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Test
- CHECK FOR AN ACTIVE DIAGNOSTIC TROUBLE CODE (DTC)
- Turn the ignition on.
- With the scan tool, read Park Assist Module DTCs.
Does the scan tool display this DTC as active?
Yes
- Go To 2
No
- The condition that caused this code to set is not present at this time. Check for an intermittent condition by inspecting the related wiring harness for chafed, pierced, pinched, and partially broken wires. Also inspect the related connectors for broken, bent, pushed out, spread, corroded, or contaminated terminals.
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
- VERIFY ABS IS ACTIVE ON THE CAN BUS
- With the scan tool, select ECU View.
- Verify that the ABS is active on the bus.
Is the ABS active on the bus?
Yes
- Go To 3
No
- Refer to NO RESPONSE FROM ABS (ANTI-LOCK BRAKE SYSTEM MODULE) and perform the No Response from ABS diagnostic procedure.
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
- DTCS STORED OR ACTIVE IN THE ANTILOCK BRAKE MODULE (ABS)
- With the scan tool, read ABS DTCs.
Are any DTCs active or stored in the ABS?
Yes
- Refer to DIAGNOSTIC CODE INDEX, ABS and perform the appropriate diagnostic procedure.
No
- Go To 4
- With the scan tool, read ABS DTCs.
- NO WHEEL SPEED SENSOR OR VEHICLE SPEED DATA IN THE ABS MODULE
- With the scan tool, check ABS wheel speed sensor data and vehicle speed data.
Are the wheel speed sensors and vehicle speed reading correctly?
Yes
- Go To 5
No
- Repair the speed sensor or vehicle speed that is not reading correctly.
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
- With the scan tool, check ABS wheel speed sensor data and vehicle speed data.
- ACTIVE COMMUNICATION DTCS IN THE BCM
- With the scan tool, select ECU View and select BCM.
- With the scan tool, read active DTCs.
Are any Communication DTCs active in the BCM?
Yes
- Refer to BODY CONTROL MODULE (BCM) - DIAGNOSTIC CODE INDEX - 2500 HD & 3500 HD and perform the appropriate diagnostic procedure.
No
- Replace and program the Park Assist Module in accordance with the Service Information. Refer to MODULE, PARK ASSIST, REMOVAL .
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.