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Home >> Chevrolet >> 1998 >> Monte Carlo LS >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 2 (Engine Controls - Tests W/Codes - 3.8L) >> Diagnostic Trouble Codes >> DTC P1651 - Fan 1 Relay Control Circuit >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different variant/trim than selected.
  1. 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.
  2. Turn ON the ignition, with the engine OFF. With a scan tool, command the Fan relay 1 ON and OFF. If the relay turns ON and OFF with each command, go to Diagnostic Aids . If the relay does NOT turn ON and OFF with each command, go to next step.
  3. Turn ignition off. Disconnect fan 1 relay connector. Turn ignition on. Check voltage between engine ground and fan 1 relay ignition feed circuit. If battery voltage is present, go to next step. If battery voltage is not present, go to step 10).
  4. Connect a test light between fan 1 relay harness connector fan 1 relay driver and ignition feed circuits. Using scan tool, command the Fan relay 1 ON and OFF. If test light flashes on and off, go to step 8). If test light does not flash on and off, go to next step.
  5. If the test lamp remain illuminated with each command, go to step 7). If the test lamp does NOT remain illuminated with each command, go to next step.
  6. Test the control circuits of the relay for a short to voltage or an open. Refer to ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. If the condition is corrected, go to step 13). If condition is still present, go to step 9).
  7. Test the control circuits of the relay for a short to ground. Refer to ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. If the condition is corrected, go to step 13). If condition is still present, go to step 9).
  8. Inspect for poor connections at the relay. Repair as needed. If the condition is corrected, go to step 13). If condition is still present, go to step 11).
  9. Inspect for poor connections at the PCM. Repair as needed. If the condition is corrected, go to step 13). If condition is still present, go to step 12).
  10. Repair the feed circuit of the relay. Refer to ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. Go to step 13).
  11. Replace the relay. Refer to BUZZERS, RELAYS & TIMERS . Go to step 13).
  12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  13. 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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