How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Neal Your Own Question
Neal, Chevy Mechanic
Category: Chevy
Satisfied Customers: 8349
Experience:  Shop Owner and Mechanic on multiple makes.
Type Your Chevy Question Here...
Neal is online now
A new question is answered every 9 seconds

2005 Chevy: duramax..probably the glow plug control module..wiring

This answer was rated:

I have a 2005 Chevy 3500 Duramax that is giving me a P0670 code - I can clear the code and it will come back after an engine start or two. I figure it's probably the glow plug control module. How can I test to make sure it's not the wiring or a bad ground before I drop the money on a new module?

I'm Neal and I am here to assist you. Only accept when you are happy with my assistance. If I can't help I will open your Question to other experts.


It should be the glow plug controller, here the diagnostic info if you want to do some testing to be sure.


DTC P0670

The glow plug controller has the ability to perform internal diagnostics for voltage and output state of the glow plugs. If the glow plug controller senses an open in the main battery supply to the glow plug controller, or a condition with any of the glow plug driver circuits, the glow plug controller will send an error message to the engine control module (ECM).

This diagnostic procedure supports the following DTC:
DTC P0670 Glow Plug Module Control Circuit

- DTC U0073 or U0106 is not set.
- The ignition is ON.
- DTC P0670 runs continuously.

The glow plug controller detects an open to the main battery supply for the glow plugs, or an open in all 8 glow plug circuits for less than 1 second.

- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.


Customer: replied 4 years ago.
Thanks Neal. On step 5, which wire is the hot wire? There's a 12-connector plug there...
It should be pin #5 5 the pink wire, that is ignition voltage
Customer: replied 4 years ago.
OK, that one is hot when the ignition is on. No obvious signs of a loose or bad connection anywhere. Time to replace the module?
Sure looks like it. It sounds like you covered everything in the diagnostic.
Neal and 2 other Chevy Specialists are ready to help you