:  Dec 17, 2007



Overview

For information on the system operation, refer to the relevant workshop manual section.

Inspection and verification

. Verify the customer concern.

. Visually inspect for obvious electrical faults.

Electrical
  • Glow plug lamp
  • Fuses
  • Glow plug relays
  • Engine management control relay
  • Wiring harness(es)
  • Electrical connector(s)
  • Glow plug(s)
  • Engine control module (ECM)

. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

. Use the approved diagnostic system or a scan tool to retrieve any diagnostic trouble codes (DTCs) before moving onto the symptom chart or DTC index.
  Make sure that all DTCs are cleared following rectification.
Make sure that all DTCs are cleared following rectification.

Symptom chart

Symptom Possible cause Action
Poor starting (extreme weather conditions)
  • Glow plugs inoperative/inefficient
  • Fuel temperature too low
Check the glow plug harnesses at the glow plugs and at the connection to the main harness. Refer to the electrical guides. Check for glow plug DTCs. The fuel system recycles fuel until operating temperature is reached to reduce this possibility.
High cold-engine emissions
  • After-glow phase inoperative
Check the glow plug harnesses at the glow plugs and at the connection to the main harness. Refer to the electrical guides. Check for glow plug DTCs. After-glow is designed to function at engine temperatures below 50 degrees C (122 degrees F), and below 2,500 rpm.
High cold-engine noise, vibration or harshness
  • After-glow phase inoperative
Check the glow plug harnesses at the glow plugs and at the connection to the main harness. Refer to the electrical guides. Check for glow plug DTCs. After-glow is designed to function at engine temperatures below 50 degrees C (122 degrees F), and below 2,500 rpm.

DTC index

:
  Generic scan tools may not read the codes listed, or may read only 5-digit codes. Match the 5 digits from the scan tool to the first 5 digits of the 7-digit code listed to identify the fault (the last 2 digits give extra information read by the manufacturer-approved diagnostic system).

:
  For a full list of ECM DTCs, refer to workshop manual section 303-14 - Electronic Engine Controls.

DTC Description Possible causes Action
P038300 Glow Plug Control Module Control Circuit Low
  • Glow plug relay, control circuit high resistance
  • Glow plug relay, control circuit short circuit to ground
  • Glow plug relay failure
Refer to the electrical guides and check the circuit. Check the relay operation. Repair/renew as necessary.
P038400 Glow Plug Control Module Control Circuit High
  • Glow plug relay, control circuit short circuit to power
  • Glow plug relay failure
Refer to the electrical guides and check the circuit. Check the relay operation. Repair/renew as necessary.
P067000 Glow Plug Control Module Control Circuit / Open
  • Glow plug relay, control circuit high resistance
  • Glow plug relay, control circuit short circuit to ground
  • Glow plug relay failure
Check the glow plug relay circuits. Refer to the electrical guides. Check the relay operation. Activate the relay and listen for an audible 'click'. Repair/renew as necessary. Clear the DTCs and test for normal operation.