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 MANUALSBUICK1998REGAL 25TH ANNIVERSARY EDITIONREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - TESTS W/CODES - 3.8LDIAGNOSTIC TROUBLE CODESDTC P1652 - FAN 2 RELAY CONTROL CIRCUITDIAGNOSTIC PROCEDURES
1998 Buick Regal 25th Anniversary Edition
Diagnostic Procedures
1998 Buick Regal 25th Anniversary EditionSECTION Diagnostic Procedures
- Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. After performing OBD system check, go to next step.
- Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between engine ground and PCM harness connector fan 2 relay driver circuit. If battery voltage is present, go to next step. If battery voltage is not present, go to step 6).
- Disconnect cooling fan connectors. Using DVOM in 10-amp scale, check current between engine ground and fan 2 relay driver circuit for 2 minutes. If current remains .05-.50 amp go to step 11). If current does not remain between .05-.50 amp, go to next step.
- Ignition off. With PCM connectors still disconnected, disconnect series/parallel and high speed fan relays. Turn ignition on. Using DVOM, check voltage between engine ground and fan 2 relay driver circuit. If voltage is zero volts, go to step 10). If voltage is not zero volts, go to next step.
- Locate and repair short to voltage in fan 2 relay driver circuit. After repairs, go to step 16).
- Check fan 2 relay ignition feed fuse. If fuse is blown, go to next step. If fuse is okay, go to step 8).
- Locate and repair short to ground in fan 2 relay ignition feed circuit. Replace fuse. After repairs, go to step 16).
- Disconnect fan 2 (high speed) relay connector. Turn ignition on. Check voltage between engine ground and fan 2 relay ignition feed circuit. If battery voltage is present, go to next step. If battery voltage is not present, go to step 13).
- Check fan 2 relay driver circuit for open or short to ground. Repair as necessary. After repairs, go to step 16). If circuit is okay, go to next step.
- Check fan 2 relay driver and fan 2 relay ignition feed circuits for faulty connection at PCM. Repair as necessary. After repairs, go to step 16). If connection is okay, go to step 14).
- Turn ignition off. Reconnect PCM connector. Disconnect high speed cooling fan relay connector. Turn ignition on. Connect a test light between fan 2 relay harness connector fan 2 relay driver and ignition feed circuits. Using scan tool, cycle fan 2 relay 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 fan 2 relay driver circuit for faulty connection at PCM. Repair as necessary. After repairs, go to step 16). If connection is okay, go to step 15).
- Locate and repair open fan 2 relay ignition feed circuit. After repairs, go to step 16).
- Replace high speed cooling fan relay. After replacing relay, go to step 16).
- Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 16).
- Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL 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.