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 Aids
To prevent replacing good components, be aware the following non-EEC related areas may be cause of problem:
- Technician did not perform brief Wide Open Throttle (WOT) after Dynamic Response Code.
- Engine did not go over 2000 RPM during WOT.
This test is only intended to diagnose:
- Throttle movement (minimum 3/4 throttle).
- RPM increase is more than 2000 RPM.
If throttle is snapped open briefly, it may not pass WOT test. Ensure throttle is depressed fully to WOT and engine speed exceeds 2000 RPM.
1) Code 77/538: System Failed To Recognize WOT Test Repeat KOER SELF-TEST as follows:
- Activate SELF-TEST.
- Start engine.
- Observe ID Code start of test.
- Observe Dynamic Response Code 1 (Code 0 with Star tester).
- Perform brief WOT.
- Testing is complete; Diagnostic Test Code (DTC) output begins.
Ensure vehicle speed reached 2000 RPM during WOT. If Code 77/538 is present, replace PCM. If Code 77/538 is not present, vehicle has passed dynamic response test. Service other codes if necessary.
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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.