I am getting a DTC P0673 Cylinder 3 glow plug circuit CEL. I saw a good post on this subject at:

https://www.ford-trucks.com/forums/1...cel-light.html

m-chan68 was recommending the following test:

".. Disconnect the four wire connector that is clipped to your FICM mounting bracket (the one with the red lock tab). Using an ohm meter set to OHMs (preferably one that auto ranges), connect the red lead to each of the four female cavities with the black lead connected to your driver side battery ground terminal. Each of the four terminals should give you no more than 2 ohms readings. If this test checks out good, your GPCM likely needs to be replaced, provided the circuit is good between the engine harness side that connects to the GPCM and the glow plug harness. Yes, and P06XX glow plug control system codes WILL throw the CHECK ENGINE light on, because it is considered an emissions affecting component."

I did this test and I got 0.7 ohms for each of the 4 female plugs. The readings would start around 1.2 - 1.4 and settle down to 0.7.

Any suggestions?

 

it may not be ur gpcm. it may be exactly wat u said. the cylinder 3 glow plug circuit.

personally, i'd take tis opportunity to change out all the glow plugs. maybe even the harness.