Circuit/System Testing

PNP Switch Circuit Malfunction (MN5)

1. Inspect the shift control cable for proper adjustment. Refer to Shift Control Cable Adjustment .
2. Ignition OFF, disconnect the harness connector at the PNP switch.
3. Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 5 ohms between the ground circuit terminal 1 and ground.
   • If greater than the specified range, test the ground circuit for an open/high resistance.
4. Verify that the scan tool ECM PNP Switch parameter is In Gear.
   • If not the specified value, test the signal circuit terminal 12 for a short to voltage. If the circuit tests normal, replace the ECM.
5. Install a 3 A fused jumper wire between the signal circuit terminal 12 and the ground circuit terminal 1. Verify that the scan tool ECM PNP Switch parameter is Park/Neutral.
   • If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
6. If all circuits test normal, test or replace the PNP switch.

CRNK Relay Circuit Malfunction

1. Ignition ON, observe the scan tool ECM Ignition 1 parameter. The reading should be B+ voltage.
   • If not the specified value, test the ECM/TRANS ignition circuit terminal 54 X2 (LNF) or terminal 19 X1 (L61/LE5) for a short to ground or an open/high resistance.
2. Ignition OFF, disconnect the CRNK relay. Refer to Relay Replacement (Attached to Wire Harness) or Relay Replacement (Within an Electrical Center) .
3. Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 5 ohms between the ground circuit terminal 85 and ground.
   • If greater than the specified range, test the ground circuit for an open/high resistance.
4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
   • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
5. Connect a test lamp between the ground circuit terminal 85 and the control circuit terminal 86.
6. Ignition ON, transmission in Park (MN5) or clutch pedal pressed (M86/MU3). Command the starter relay ON and OFF with a scan tool (MN5/MU3), or turn the ignition switch between the start and run positions (M86). The test lamp should turn ON and OFF when changing between the commanded states.
   • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
   • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
7. Ignition OFF, connect the CRNK relay. Disconnect the X1 harness connector at the starter solenoid.
8. Ignition ON, transmission in park (MN5) or clutch pedal pressed (M86/MU3). Command the starter relay ON with a scan tool (MN5/MU3), or turn the ignition switch to the START position (M86). Verify that a test lamp illuminates between the starter terminal A X1 and ground.
   • If the test lamp does not illuminate, test the starter control circuit for an open/high resistance. If the circuit tests normal, test or replace the CRNK relay.
9. If all circuits test normal, test or replace the starter.