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 MANUALSPONTIAC19906000 LE, 4D SEDAN, 2.5 RREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - BASIC TESTINGNO START DIAGNOSISNO START - ENGINE CRANKS OKAY (TBI WITH HEI)IGNITION SYSTEM
1990 Pontiac 6000 LE, 4D Sedan, 2.5 R
Ignition System
1990 Pontiac 6000 LE, 4D Sedan, 2.5 RSECTION Ignition System
- Disconnect tachometer wire at distributor TACH terminal (if equipped). A shorted tachometer will not allow vehicle to start.
- Check for battery voltage at BAT terminal at distributor with ignition on. Repair as necessary.
- Connect ST-125 spark tester to end of one plug wire and crank engine. If spark occurs, check fuel delivery.
- If spark does not occur, disconnect 4-wire EST connector at distributor. If spark now occurs, replace pick-up coil in distributor.
- If spark does not occur, reconnect EST connector and check voltage at TACH terminal at distributor with ignition on.
- If voltage is less than one volt, repair faulty coil connection or replace faulty coil. If voltage is 1-10 volts, replace ignition module and recheck for spark. If spark still does not occur, replace ignition coil.
- If voltage reading at TACH terminal of distributor is greater than 10 volts, remove and invert distributor cap with wires connected. Fabricate an HEI coil spark tester by trimming a spark plug boot and connecting it to ST-125 spark tester. See Figure . Crank engine.
- If spark occurs, check cap for cracks, water or other defects. Check pick-up coil connector and ignition coil lead wire colors. Ignition coil with Yellow and Red wires should be used with a Yellow pick-up coil connector. Ignition coil with White and Red wires should be used with a Clear or Black pick-up coil connector.
- If spark does not occur, turn ignition off and disconnect pick-up coil leads from module. Turn ignition on. With voltmeter connected to distributor TACH terminal and fabricated coil spark tester connected, momentarily touch test light, connected to a remote voltage source (1.5-8.0 volts), to ignition module terminal "P."
- If voltage at TACH terminal does not drop, check ignition module ground and for open in wires from ignition coil to module. If all is okay, replace ignition module.
- If voltage at TACH terminal does drop, check for spark at spark tester as test light is removed from terminal "P". If spark occurs, check pick-up coil connections and check for 500-1500 ohms resistance at pick-up coil leads. Repair as necessary.
- If spark does not occur, test ignition module with module tester. If module tests okay, check ignition coil wire. If module tester is not available, replace ignition coil and again touch terminal "P." If spark occurs, system is okay. If spark does not occur, reinstall original ignition coil and replace ignition module.
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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.