2006 Duramax replaced the glow plug control module and had the computer reprogrammed two days later I'm getting codes P0671 thru P0678. Is it possible all glow plugs are bad?

 

I moved your thread to the appropriate section.

 

Looks like 1 and 8 are bad.

Here's what you need.

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. See: Diagnostic Trouble Code Tests and Associated Procedures

CIRCUIT/SYSTEM DESCRIPTION
The glow plug controller has the ability to perform internal checks, an open or a short to ground on each of the glow plug circuits. If the glow plug controller senses a problem in a glow plug circuit, the glow plug on the affected cylinder will be disabled and the glow plug controller will send an error message to the engine control module (ECM). If this condition exists, the DTC will set.

CONDITIONS FOR RUNNING THE DTC

* The ignition is ON.
* DTCs P0671-P0678 run continuously.

CONDITIONS FOR SETTING THE DTC
The glow plug controller detects that the glow plug control circuit is open, shorted to ground, or has more than 1 ohm of resistance.

ACTION TAKEN WHEN THE DTC SETS

* 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.

CONDITIONS FOR CLEARING THE DTC

* The control module turns OFF the 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.

CIRCUIT/SYSTEM VERIFICATION
Refer to Testing for Intermittent Conditions and Poor Connections if you cannot duplicate the conditions. See: Diagrams\Diagnostic Aids

* If DTC P064C is also set, diagnose DTC P064C first.

CIRCUIT/SYSTEM TESTING

IMPORTANT:

* If a glow plug control circuit is shorted to 12 volts , the glow plug will be damaged and the glow plug must be replaced.
* If a glow plug is replaced and the tip is missing or burned off, the cylinder head must be removed and all debris be cleaned out of the cylinder.

1. With the ignition ON and the glow plugs not commanded ON, probe the affected glow plug with a test lamp connected to a ground. Observe that the test lamp does not illuminate.

o If the test lamp does illuminate, test the glow plug control circuit for a short to voltage or for a faulty glow plug control module (GPCM).

2. With the ignition ON, probe the affected glow plug with an unpowered test lamp connected to ground. Command the glow plugs ON with a scan tool and observe the test lamp.

o If the test lamp does not illuminate, test the affected glow plug harness between the glow plug control module and the glow plug for an open, short to ground or high resistance.

3. With the ignition OFF and the affected glow plug disconnected, measure the resistance between the affected glow plug terminal and ground with a DMM for less than 1 ohm .

o If the resistance is more than 1 ohm , test the affected glow plug control circuit for a short to voltage and replace the damaged glow plug.

4. With the ignition OFF and the glow plug control module harness disconnected, measure the resistance between the affected glow plug harness connector and the glow plug control module harness connector for less than 1 ohm resistance.

o If the resistance is more than 1 ohm , repair the harness.
o If the resistance is less than 1 ohm , replace the glow plug control module.

COMPONENT TESTING
With the igniting OFF and the affected glow plug disconnected, measure the resistance between the affected glow plug terminal of the glow plug and ground with a DMM for less than 1 ohm .

* If the resistance is more than 1 ohm , replace the affected glow plug.

REPAIR INSTRUCTIONS



* Control Module References for ECM replacement, setup, and programming
* Glow Plug Replacement - Bank 1 or Glow Plug Replacement - Bank 2

 

agree the 1 and 8 are ad replace tehm and see if they go away.