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.
MIL Circuit Troubleshooting
MIL Circuit Troubleshooting
- Gauge control module check
-1. Turn the vehicle to the ON mode.
-2. Do the gauge self-diagnostic function .
Does the MIL flash?
YES
Go to step 2.
NO
Substitute a known-good gauge control module , then recheck. If the symptom/indication goes away with a known-good gauge control module, replace the original gauge control module .
- PCM check
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Connect the HDS to the DLC.
-3. Turn the vehicle to the ON mode.
-4. Check the parameter (s) below with the HDS.
Signal Threshold Current conditions Values Unit Values Unit SCS Short Do the current condition (s) match the threshold?
YES
Go to step 3.
NO
Update the PCM if it does not have the latest software, or substitute a known-good PCM , then recheck. If the symptom/indication goes away and the PCM was updated, troubleshooting is complete. If the symptom/indication goes away and the PCM was substituted, replace the original PCM .
- Shorted wire check (SCS line)
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Jump the SCS line with the HDS.
-3. Disconnect the following connector.
PCM connector A (51P) -4. Disconnect the HDS.
-5. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode PCM connector A (51P): disconnected Test point 1 PCM connector A (51P) No. 44 Test point 2 Body ground Is there continuity?
YES
Repair a short in the SCS wire between the PCM (A44) and the DLC.
NO
The SCS wire is OK. Update the PCM if it does not have the latest software, or substitute a known-good PCM , then recheck. If the symptom/indication goes away and the PCM was updated, troubleshooting is complete. If the symptom/indication goes away and the PCM was substituted, replace the original PCM .
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.