7.3 Diesel error code for glow plugs on #5,#7 Cylinder
 

Hi,
Have an 01 7.3 diesel throwing a glow plug code for cylinder #5 and #7. The dealership says it is usually the control module and not the glow plugs which seems like it would make sense. How likely is it to lose both of those glow plugs simultaneously? Anyone know where that control module is and how to check it? Are cylinder #5 and #7 paired to the same control module?
Thanks,

Thread moved to the 7.3 forum.

My excursion threw a #2 glow plug code at me, but the engine ran rough at startup until warm. Turns out the wiring harness under the valve cover came partly unplugged. I replace the harness while I had the cover off, all is well now. I would check and make sure the harness is plugged in before going any further, this is a common problem.

If you have an mulit-meter that can read ohms, you can check the glow plugs without pulling the valve covers.

Unplug the flat 9 pin connector on the inboard side of the passenger valve cover. It's near the center. The very back 2 pins are for glow plugs #5, & #7. Check those pins against a good ground (or battery ground). A good glow plug should read between 0.1 - 2.0 ohms.

The GPCM is in the valley of the motor on the passenger side. It's a rectangular box with 2 large plugs on it. The wires from these plugs run to each of the valve covers.