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.
Ignition Module Circuits
2000 Saturn LW2 AutomaticSECTION Ignition Module Circuits
- Disconnect ignition module. Turn ignition on. Measure voltage between ground and ignition module IGN 1 circuit at ignition module harness connector. If battery voltage is present, go to next step. If battery voltage is not present, check EIS fuse (10-amp) located in underhood fuse block, and check IGN 1 circuit for open or short to ground. Repair as necessary.
- Measure voltage between ignition module IGN 1 circuit and ignition module ground circuit at ignition module harness connector. If battery voltage is present, go to next step. If battery voltage is not present, repair open ground circuit.
- Using test light connected to 7X reference signal out circuit at ignition module harness connector, momentarily probe negative battery terminal, and then positive battery terminal while monitoring CKP active counter with scan tool. If counter increments, go to next step. If counter does not increment, 7X reference signal out circuit or PCM is faulty. Repair as necessary.
- Measure resistance between CKP sensor circuits at ignition module. If resistance is 500-900 ohms, go to next step. If resistance is less than 500 ohms, go to step 6 . If resistance is greater than 900 ohms, go to step 7 .
- Disconnect CKP sensor. Check for continuity between ground and CKP sensor signal high circuit at CKP sensor harness connector. If continuity is present, repair CKP sensor signal high circuit for short to ground. If continuity is not present, go to step 8 .
- Disconnect CKP sensor. Check for continuity between CKP sensor signal high circuit and low circuit at CKP sensor harness connector. If continuity is present, repair CKP sensor circuits for short together. If continuity is not present, replace CKP sensor.
- Disconnect CKP sensor. Check for open in CKP sensor signal high circuit and low circuit. Repair as necessary. If circuits are okay, CKP sensor or terminal connections are faulty.
- Reconnect CKP sensor. Using DVOM set to AC scale, measure voltage between CKP sensor high circuit and low circuit at ignition module harness connector while cranking engine. If AC voltage is greater than 200 mV, ignition module or terminal connections are faulty. If AC voltage is 200 mV or less, check CKP sensor for proper installation. If installation is okay, replace CKP sensor.
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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.