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 MANUALSCHEVROLET1999SUBURBAN C2500, 6.5 FREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROL SYSTEM - TESTS W/CODES - DTC P1537-U1193DTC P1672DTC P1672: LOW OIL LEVEL LIGHT CONTROL CIRCUIT (3.8L "G" BODY)DIAGNOSTIC PROCEDURES
1999 Chevrolet Suburban C2500, 6.5 F
Diagnostic Procedures
1999 Chevrolet Suburban C2500, 6.5 FSECTION Diagnostic Procedures
- Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
- Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using a DVOM, check voltage between oil level switch control circuit at PCM harness connector and ground. If battery voltage is present, go to next step. If battery voltage is not present, go to step 6.
- Connect DVOM between oil level switch light control circuit at PCM harness connector and chassis ground. Monitor reading for 2 minutes. If DVOM reads.05-.50 amp, go to step 11. If DVOM does not read.05-.50 amp, go to next step.
- Turn ignition off. Disconnect instrument panel harness connector (leave PCM harness connector disconnected). Turn ignition on. Check voltage between low engine oil level light control circuit and ground. If voltage reading is zero volts, go to step 10. If voltage reading is not zero volts, go to next step.
- Locate and repair short to voltage in low engine oil level light control circuit. Repair as necessary. After repairs, go to step 15.
- Check ignition feed fuse for instrument panel indicators. If fuse is blown, go to next step. If use is not blown, go to step 8.
- Locate and repair short to ground in ignition feed circuit for instrument panel indicators. Replace fuse. After repairs, go to step 15.
- Disconnect instrument cluster harness connector. Turn ignition on. Check voltage between ignition feed circuit for instrument cluster indicators and ground. If battery voltage is present, go to next step. If battery voltage is not present, go to step 13.
- Check for open or short to ground in low oil level light control circuit. Repair as necessary. After repairs, go to step 15. If circuit is okay, go to next step.
- Check for poor terminal connections at instrument panel and PCM. Repair as necessary. After repairs, go to step 15. If connections are okay, diagnose instrument panel assembly.
- Turn ignition off. Reconnect PCM harness connector. Disconnect instrument cluster connector. Turn ignition on. Using a test light, connect test light between low engine oil level light control circuit and ignition feed circuit at instrument panel harness connector. Using scan tool, cycle the low engine oil level light on and off. If test light flashes on and off, see DIAGNOSTIC AIDS . If test light does not flash on and off, go to next step.
- Check low engine oil level light control circuit for poor connection at PCM. Repair as necessary. After repairs, go to step 15. If connection is okay, go to step 14.
- Locate and repair open in ignition feed circuit to instrument panel indicators. Repair as necessary. After repairs, go to step 15.
- Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
- Using scan tool, read and record FAILURE RECORDS data, and clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, select SPECIFIC DTC INFO for this DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2. If scan tool does not display that this DTC FAILED THIS IGN, repair is complete.
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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.