DTC Troubleshooting: P1031 (183)
DTC P1031:
 Fuel Heater Circuit Malfunction
NOTE: Before you troubleshoot, record all freeze data and review the general troubleshooting information.
  1. Turn the ignition switch ON (II).
  1. Clear the DTC with the HDS.
  1. Do the FUEL HEATER ON/OFF in the INSPECTION MENU with the HDS.
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P1031 indicated?
YES -
Go to Step 5 .
NO -
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the fuel heater the fuel heater relay and the ECM.■
  1. Turn the ignition switch OFF.
  1. Check the No. 25 FUEL HEATER MONITOR (7.5 A) fuse in the under-hood fuse/relay box.
Is the fuse OK?
YES -
Go to Step 7 .
NO -
Replace the No. 25 FUEL HEATER MONITOR (7.5 A) fuse, then go to Step 18 .
Is the fuel heater relay OK?
YES -
Go to Step 9 .
NO -
  1. Disconnect ECM connector No. 1 (96P).
  1. Disconnect the fuel heater 2P connector.
  1. Turn the ignition switch ON (II).
  1. 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 Step 17 .
NO -
Go to Step 13 .
  1. Connect under-hood fuse/relay box connector J (10P) terminal No. 5 to body ground with a jumper wire.
  1. Check for continuity between ECM connector No. 1 terminal No. 37 and body ground.
Is there continuity?
YES -
Go to Step 15 .
NO -
Repair open in the wire between the under-hood fuse/relay box and ECM connector No. 1 terminal No. 37, then go to Step 18 .
  1. Check for continuity between under-hood fuse/relay box connector J (10P) terminal No. 5 and fuel heater 2P connector terminal No. 2.
Is there continuity?
YES -
Go to Step 16 .
NO -
Repair open in the wire between the under-hood fuse/relay box and the fuel heater, then go to Step 18 .
  1. Check for continuity between fuel heater 2P connector terminal No. 1 and body ground.
Is there continuity?
YES -
Substitute a known-good under-hood fuse/relay box, then go to Step 18 and recheck. If DTC P1031 is not indicated, replace the original under-hood fuse/relay box, then go to Step 18 . If DTC P1031 is indicated, go to Step 23 .
NO -
Repair open in the wire between the fuel heater and body ground (G401), then go to Step 18 .
  1. Turn the ignition switch OFF.
  1. Reconnect all connectors.
  1. Turn the ignition switch ON (II).
  1. Reset the ECM with the HDS.
  1. Do the FUEL HEATER ON/OFF in the INSPECTION MENU with the HDS.
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P1031 indicated?
YES -
Check for poor connections or loose terminals at the under-hood fuse/relay box and the ECM, then go to Step 1 .
NO -
Troubleshooting is complete. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.■
  1. Reconnect all connectors.
  1. Do the FUEL HEATER ON/OFF in the INSPECTION MENU with the HDS.
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P1031 indicated?
YES -
Check for poor connections or loose terminals at the under-hood fuse/relay box and the ECM. If the ECM was updated, substitute a known-good, then go to Step 25 . If the ECM was substituted, go to Step 1 .
NO -
If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.■