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
- READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR THE DTC TO RETURN NOTE:
This diagnostic procedure diagnoses single battery or dual battery systems. Proceed as equipped.
- With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
- With the scan tool, run a vehicle Scan Report, or record the Environmental Data related to the DTCs.
- With the scan tool, erase all DTCs.
- Turn the ignition off for a minimum of 10.0 seconds.
- Turn the ignition on.
- Using the recorded Environmental Data and the When Monitored Conditions above, operate the vehicle in the conditions that set the DTC.
- With the scan tool, read Body Control Module (BCM) DTCs.
Did the DTC return?
Yes
- Go To 2
No
- Perform the appropriate INTERMITTENT CONDITION diagnostic procedure. Refer to TESTING FOR AN INTERMITTENT CONDITION .
- CHECK THE OPERATION OF THE 12-VOLT MAIN BATTERY AND AUXILIARY BATTERY (IF EQUIPPED) NOTE:
This DTC may also set if the 12-volt Main Battery, or Auxiliary Battery, does not operate properly.
- Check the 12.0 Volt Main Battery, and Auxiliary Battery (if equipped), for proper operation. Refer to DIAGNOSIS AND TESTING - DUAL BATTERIES - 12 VOLT SYSTEM
.
Does the 12-volt Main Battery, and Auxiliary Battery, operate properly?
Yes
- Go To 3
No
- Repair or replace the inoperative Battery (Main or Auxiliary) in accordance with the Service Information. Refer to BATTERY, REMOVAL AND INSTALLATION .
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
- Check the 12.0 Volt Main Battery, and Auxiliary Battery (if equipped), for proper operation. Refer to DIAGNOSIS AND TESTING - DUAL BATTERIES - 12 VOLT SYSTEM
.
- CHECK FOR STARTING, CHARGING OR IGNITION RELATED DTC(S) PRESENT IN THE POWERTRAIN CONTROL MODULE (PCM)
- Turn the ignition on.
- With the scan tool, read PCM DTCs and record on the repair order.
Are there any starting, ignition or charging DTCs in the PCM?
Yes
- Repair the Powertrain Control Module (PCM) DTCs. Refer to 3.0L [EFH], DIAGNOSTIC CODE INDEX or 3.0L [EFC], DIAGNOSTIC CODE INDEX .
No
- With the scan tool, perform the PCM programming procedure. Refer to MODULE, POWERTRAIN CONTROL (PCM), MODULE PROGRAMMING .
- 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.