Circuit/System Testing

PNP Switch Circuit Malfunction - 6T40/6T45 (MH8)

1. Inspect the range selector lever cable for proper adjustment. Refer to Range Selector Lever Cable Adjustment .
2. Ignition OFF, disconnect the harness connector at the transmission inline 20-way connector.
3. Ignition ON, test for greater than 10 V on the park/neutral signal circuit terminal 3.
   • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
4. Ignition OFF, remove the control valve body cover. Refer to Control Valve Body Cover Replacement .
5. Connect the transmission inline 20-way connector, with the cover removed.
6. Disconnect the shift position switch connector from the TCM. Refer to Control Solenoid Valve and Transmission Control Module Assembly Replacement .
7. Ignition ON, verify that the scan tool ECM PNP Switch parameter is In Gear.
   • If not the specified value, replace the ECM.
8. Connect a 3 A fused jumper wire between the park/neutral signal terminal F of the TCM and ground. The scan tool PNP Switch parameter should be Park/Neutral when the terminal is connected to ground.
   • If not the specified value, replace the ECM.
9. If all circuits test normal, test or replace the shift position switch.

PNP Switch Circuit Malfunction - 6T70 (MH2)

1. Inspect the range selector lever cable for proper adjustment. Refer to Range Selector Lever Cable Adjustment .
2. Ignition OFF, disconnect the harness connector at the transmission inline 20-way connector.
3. Ignition ON, test for greater than 10 V on the park/neutral signal circuit terminal 20.
   • If there is less than 10 V on the park/neutral signal circuit, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
4. Ignition OFF, remove the control valve body cover. Refer to Control Valve Body Cover Replacement .
5. Connect the transmission inline 20-way connector, with the cover removed.
6. Disconnect the internal mode switch connector at the control solenoid valve assembly.
7. Ignition ON, verify that the scan tool PNP Switch parameter is In Gear.
   • If not the specified value, replace the ECM.
8. Connect a 3 A fused jumper wire between the park/neutral signal terminal F at the control solenoid valve assembly and ground. The scan tool PNP Switch parameter should be Park/Neutral when the terminal is connected to ground.
   • If not the specified value, replace the ECM.
9. If all circuits test normal, test or replace the internal mode switch.

Start Relay Circuit Malfunction

1. Ignition OFF, disconnect the START relay.
2. Ignition OFF and scan tool disconnected, open and close the driver door, and wait 45 seconds. Test for less than 5 Ω between the relay ground circuit terminal 85 and ground.
   • If greater than the specified value, test the ground circuit for an open/high resistance.
3. 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.
4. Connect a test lamp between the relay coil ground circuit terminal 85 and the relay coil control circuit terminal 86.
5. Ignition ON, transmission in Park, turn the ignition switch between the start and run positions. The test lamp should turn ON and OFF when changing between the commanded states.
   • If the test lamp is always ON, test the relay coil control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
   • If the test lamp is always OFF, test the relay coil control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
6. Connect the START relay.
7. Install a test lamp between the starter terminal A X1 and ground.
NOTE:

The engine may begin to crank.

8. Ignition ON, transmission in Park, turn the ignition switch to the start position. The test lamp should illuminate.
   • If the test lamp does not illuminate, test the starter control circuit terminal 87 for an open/high resistance. If the circuit tests normal, test or replace the START relay.
9. If all circuits test normal, test or replace the starter.