Circuit/System Testing
WARNING: This page is about a different car, the 2009 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the 3 cooling fan relays listed below:
- Fan 1 relay
- Fan 2 relay
- Fan 3 relay
- Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 85 of each relay and ground.
- If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
- Verify that a test lamp does not illuminate between the ignition circuit terminal 85 and the control circuit terminal 86 of each relay.
- If the test lamp illuminates, test the control circuit for a short to ground. If the circuit test normal, replace the ECM.
- Remove the test lamp.
- Ignition ON, command the affected relay ON using a scan tool. Verify the affected scan tool FC Relay Control Ckt. Short Volts Test Status parameter is OK.
- For the fan 1 relay, use the scan tool Fan Relay 1 command.
- For the fan 2 and fan 3 relays, use the scan tool relay 2 and 3 command.
- If not the specified value, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- Install a 3A fused jumper wire between the control circuit terminal 86 and the ignition circuit terminal 85. Command the affected relay ON with a scan tool. Verify the scan tool Relay Control Ckt Short Volts Test Status parameter is Fault.
- If not the specified value, test the control circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
- If all circuits and the ECM test normal, replace the affected relay.