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 System
2000 Saturn LS AutomaticSECTION Ignition System
- Perform OBD system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
- Check ignition control module ignition feed circuit fuse and fuel injector ignition feed circuit fuse. If either fuse is blown, locate and repair short to ground in suspect ignition feed circuit. If fuses are okay, go to next step.
- Using scan tool, command fuel pump on. If fuel pump runs, go to next step. If fuel pump does not run, see FUEL PUMP ELECTRICAL CIRCUIT (VIN K) or FUEL PUMP ELECTRICAL CIRCUIT (VIN 1) .
- Turn ignition off. Install fuel pressure gauge. See BASIC FUEL SYSTEM CHECKS . Turn ignition on and observe fuel pressure. Fuel pressure should be 48-55 psi (3.4-3.8 kg/cm2 ) and hold steady. If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, diagnose fuel system. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article.
- Turn ignition off. Remove fuel pressure gauge. Connect scan tool. Turn ignition on. Using scan tool, select ENGINE DATA 1. Observe engine RPM while cranking engine. If scan tool indicates engine RPM, go to step 17 . If scan tool does not indicate engine RPM, go to next step.
- Turn ignition off. Disconnect ignition control module harness connector. Turn ignition on. Connect test light between ignition positive feed circuit and ground circuit at ignition control module harness connector. If test light illuminates, go to step 8 . If test light does not illuminate, go to next step.
- Leave ignition control module harness connector disconnected. Using test light connected to ground, probe ignition positive feed circuit at ignition control module harness connector. If test light illuminates, go to step 39 . If test light does not illuminate, go to step 40 .
- Turn ignition off. Reconnect ignition control module harness connector. Disconnect 18X CKP sensor harness connector. Turn ignition on. Measure voltage between 18X CKP sensor feed circuit and CKP sensor ground circuit at CKP sensor harness connector. If voltage is near battery voltage, go to next step. If voltage is not near battery voltage, go to step 11 .
- Measure voltage between 18X CKP sensor signal circuit and CKP sensor ground circuit at CKP sensor harness connector. If voltage is 6-8 volts, go to next step. If voltage is not 6-8 volts, leave DVOM connected and go to step 14 .
- Check for poor connections at CKP sensor. Repair as necessary. If connections are okay, go to step 41 .
- Measure voltage between engine ground and 18X CKP sensor feed circuit at CKP sensor harness connector. If voltage is near battery voltage, go to next step. If voltage is not near battery voltage, go to step 13 .
- Turn ignition off. Leave CKP sensor harness connector disconnected. Disconnect ignition control module harness connector. Check for open in CKP sensor ground circuit. Repair as necessary. If ground circuit is okay, go to step 38 .
- Turn ignition off. Leave 18X CKP sensor harness connector disconnected. Disconnect ignition control module harness connector. Check 18X CKP sensor feed circuit for open or short to ground. Repair as necessary. If circuit is okay, go to step 38 .
- Turn ignition off. Disconnect ignition control module harness connector. Turn ignition on. If DVOM displays battery voltage, go to next step. If DVOM does not display battery voltage, go to step 16 .
- Locate and repair short to voltage in 18X CKP sensor signal circuit.
- Turn ignition off. Check 18X CKP sensor signal circuit for open, short to chassis ground or short to sensor ground. Repair as necessary. If signal circuit is okay, go to step 38 .
- Turn ignition off. Disconnect all fuel injector harness connectors. Turn ignition on. Connect fuel injector test light to each fuel injector harness connector. If test light illuminates for any of the injectors, go to next step. If test light does not illuminate for any injector, go to step 19 .
- Leave fuel injector harness connectors disconnected. Turn ignition off. Disconnect PCM. Turn ignition on. Connect fuel injector test light to each fuel injector harness connector. If test light illuminates for any of the injectors, go to step 43 . If test light does not illuminate for any injector, go to step 46 .
- Leave fuel injector harness connectors disconnected. Connect fuel injector test light to a fuel injector harness connector and crank engine. Repeat for each fuel injector. If test light flashes for each fuel injector, go to step 24 . If test light does not flash for each fuel injector, go to next step.
- If test light flashed for any fuel injector, go to next step. If test light did not flash for any fuel injector, go to step 22 .
- Turn ignition off. Leave fuel injector harness connectors disconnected. Disconnect PCM. Check for open in fuel injector control circuits associated with fuel injector circuit that did not flash test light. Repair as necessary. If fuel injector circuits are okay, go to step 44 .
- Leave fuel injector harness connectors disconnected. Turn ignition on. Using test light connected to ground, probe ignition positive feed circuit to each fuel injector. If test light illuminates, go to step 24 . If test light does not illuminate, go to next step.
- Locate and repair open in ignition positive feed circuit to fuel injector.
- Turn ignition off. Install Spark Tester (J 26792) to cylinder No. 1, 2 and 3 (one at a time). Connect spark plug wire of companion cylinder to ground (i.e., 1/4, 2/5, 3/6). Crank engine and observe spark tester. If spark is present at all cylinders, go to step 34 . If spark is not present at all cylinders, go to next step.
- If spark is present at any cylinder, go to step 30 . If spark is not present at any cylinder, go to next step.
- Turn ignition off. Disconnect 18X CKP sensor harness connector. Turn ignition on. Measure voltage between ground and CKP sync signal at CKP sensor harness connector. If voltage is 6-8 volts, go to next step. If voltage is not 6-8 volts, go to step 28 .
- Check for poor connections at CKP sensor harness connector. Repair as necessary. If connections are okay, go to step 41 .
- Turn ignition off. Disconnect ignition control module harness connector. Turn ignition on. Check CKP sensor sync signal circuit for short to voltage or short to 18X CKP sensor feed circuit. Repair as necessary. If sync signal circuit is okay, go to next step.
- Turn ignition off. Check CKP sensor sync signal circuit for short to chassis ground or sensor ground. Repair as necessary. If sync signal circuit is okay, go to step 38 .
- Inspect ignition coils and spark plug wires associated with cylinders that did not indicate spark. Repair as necessary. If ignition coils and spark plug wires are okay, go to next step.
- Measure ignition coil secondary resistance. If resistance is 5000-8000 ohms, go to next step. If resistance is not 5000-8000 ohms, replace ignition coil.
- Measure resistance of spark plug wires associated with cylinders that did not indicate spark. If resistance is 1000-1500 ohms per foot, go to next step. If resistance is greater than specified, replace spark plug wires.
- Remove ignition coils associated with cylinders that did not indicate spark. Connect test light across ignition coil primary circuit associated with cylinders that did not indicate spark. Crank engine and observe test light. If test light flashes continuously, go to step 45 . If test light does not flash continuously, go to step 42 .
- Remove spark plugs from all cylinders. Inspect spark plugs for excessive fouling. If spark plugs are fouled, check engine mechanical condition. Repair as necessary. If spark plugs are okay, go to next step.
- Check for the following:
- Short between 18X CKP and CKP sync signal inputs to ignition control module.
- Short between 18X and 3X reference signal inputs to PCM.
- Stuck TP sensor.
- Faulty ECT sensor.
- Unresponsive MAP sensor.
- Faulty MAF sensor.
- Faulty IAC valve.
- Test fuel for contamination. Clean fuel system if necessary. If fuel is okay, go to next step.
- Check for bent push rods, faulty or incorrect camshaft, leaking or sticky valves or rings, excessive valve deposits, loose or worn rocker arms, weak valve springs, incorrect valve timing or a leaking head gasket. Repair as necessary.
- Check for poor connections at ignition control module harness connector. Repair as necessary. If no problem is found, go to step 42 .
- Locate and repair open in ignition control module ground circuit.
- Locate and repair open in ignition feed circuit to ignition control module.
- Replace 18X CKP sensor.
- Replace ignition control module.
- Locate and repair short to ground in fuel injector control circuits associated with test light that remained illuminated.
- Check for poor connections at PCM. Repair as necessary. If connections are okay, go to step 46 .
- Replace ignition coils associated with cylinders that did not indicate spark.
- Replace PCM. Perform PCM relearn procedures.
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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.