LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Pontiac >> 1996 >> Trans Sport >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P1641 - Mil Control Circuit >> Diagnostic Procedures
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
  2. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between engine ground and PCM harness connector MIL driver circuit. If voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 6).
  3. Using DVOM in 10-amp scale, check current between engine ground and MIL driver circuit for 2 minutes. If current remains 0.05-1.50 amps go to step 11). If current does not remain as specified, go to next step.
  4. Turn ignition off. With PCM connectors disconnected, disconnect I/P connectors. Turn ignition on. Using DVOM, check voltage between engine ground and MIL driver circuit. If MIL driver voltage is zero volts, go to step 10). If voltage is more than zero volts, go to next step.
  5. Locate and repair short to voltage in MIL driver circuit. After repairs, go to step 15).
  6. Check I/P indicators ignition feed fuse. If fuse is blown, go to next step. If fuse is okay, go to step 8).
  7. Locate and repair short to ground in I/P indicators ignition feed circuit. Replace fuse and go to step 15).
  8. Disconnect I/P connectors. Turn ignition on. Check voltage between engine ground and I/P indicators ignition feed circuit. If voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 13).
  9. Check MIL driver circuit for open or short to ground. If a problem is found, repair as necessary and go to step 15). If no problem is found, go to next step.
  10. Check MIL driver and I/P indicators ignition feed circuits for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 15). If connection is okay, diagnose and repair I/P problem.
  11. Turn ignition off. Reconnect PCM connectors. Disconnect I/P connectors. Turn ignition on. Connect a test light between I/P harness connector MIL driver and ignition feed circuits. Using scan tool, cycle MIL on and off. If test light flashes on and off, go to DIAGNOSTIC AIDS. If test light does not flash on and off, go to next step.
  12. Check MIL driver circuit for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 15). If connection is okay, go to step 14).
  13. Locate and repair open I/P indicators ignition feed circuit Go to step 15).
  14. Replace PCM. Program replacement PCM using required equipment. Go to next step.
  15. 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 DTC P1641. If scan tool displays DTC P1641 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1641 FAILED THIS IGN, repair is complete.
scientia non olet · About LEMON Manuals