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.
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HOMESERVICE MANUALSPONTIAC19846000 STEREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMEGR SYSTEM - V6 DIESEL (CALIF)SYSTEM TESTINGENGINE SPEED CHECK
1984 Pontiac 6000 STE
Engine Speed Check
1984 Pontiac 6000 STESECTION Engine Speed Check
The ECM monitors engine speed through the tach lead from terminal "R" of the alternator. With key "ON," CEL will remain "ON" until engine speed exceeds 400 RPM. If tach signal is lost, CEL will remain "ON" after engine exceeds 400 RPM.
- This step checks for a 5 volt reference. Normal reading should be about 5 volts. If voltage reference is lost, CEL will remain "ON" at any RPM.
- This step checks for a grounded wire on the ECM side of the CEL bulb circuit. A grounded wire will keep CEL "ON" with engine running.
- This step checks for tach signal output for alternator. This signal should be more than 7 volts A.C. at idle and increase slightly with increased RPM. If voltage is more than 7 volts A.C., fault is not in alternator or wiring up to point of measurement.
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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.