DTC Troubleshooting: P1031 (183-2)

DTC P1031:  Fuel Heater Circuit Malfunction

1.Turn the ignition switch ON (II).

2.Clear the DTC with the HDS.

3.Do the FUEL HEATER ON/OFF in the INSPECTION MENU with the HDS.

4.Check for Temporary DTCs or DTCs with the HDS.

Is DTC P1031 indicated?


YES - Go to 5.


NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the fuel heater relay and the ECM.n


5.Turn the ignition switch OFF.

6.Check the No. 31 FUEL HEATER MONITOR (7.5 A) fuse in the under-hood fuse/relay box.

Is the fuse OK?


YES - Go to 7.


NO - Replace the No. 31 FUEL HEATER MONITOR (7.5 A) fuse, then go to 18.


7.Disconnect the fuel heater relay.

8.Check the fuel heater relay.

Is the fuel heater relay OK?


YES - Go to 9.


NO - Replace the fuel heater relay, then go to 18.


9.Disconnect ECM connector No. 1 (96P).

10.Disconnect the fuel heater 2P connector.

11.Turn the ignition switch ON (II).

12.Measure voltage between ECM connector No. 1 terminal No. 37 and body ground.

 

Is there battery voltage?


YES - Repair short to power in the wire between the fuel heater relay and ECM connector No. 1 terminal No. 37, then go to 17.


NO - Go to 13.


13.Connect fuel heater relay 4P connector terminal No. 2 to body ground with a jumper wire.

 

14.Check for continuity between ECM connector No. 1 terminal No. 37 and body ground.

 

Is there continuity?


YES - Go to 15.


NO - Repair open in the wire between the fuel heater relay and ECM connector No. 1 terminal No. 37, then go to 18.

15.Check for continuity between fuel heater relay 4P connector terminal No. 2 and fuel heater 2P connector terminal No. 2.

 

Is there continuity?


YES - Go to 16.


NO - Repair open in the wire between the fuel heater relay and the fuel heater, then go to 18.

16.Check for continuity between fuel heater 2P connector terminal No. 1 and body ground.

 

Is there continuity?


YES - Go to 23.


NO - Repair open in the wire between the fuel heater and G301, then go to 18.


17.Turn the ignition switch OFF.

18.Reconnect all connectors.

19.Turn the ignition switch ON (II).

20.Reset the ECM with the HDS.

21.Do the FUEL HEATER ON/OFF in the INSPECTION MENU with the HDS.

22.Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?


YES - If DTC P1031 is indicated, check for poor connections or loose terminals at the fuel heater relay and the ECM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.


NO - Troubleshooting is complete.n

23.Update the ECM if it does not have the latest software, or substitute a known-good ECM.

24.Do the FUEL HEATER ON/OFF in the INSPECTION MENU with the HDS.

25.Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?


YES - If DTC P1031 is indicated, check for poor connections or loose terminals at the fuel heater relay and the ECM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.


NO - If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM.n