2001 X 7.3 psd. Service engine soon light on. Code reader says cylinder 2,4,6,8 glow plug inop. Changed all glow plugs and gpr. Still have light with same codes. Wondering if GPCM might be problem. Any thoughts?

 

All those cylinders are on the drivers side. maybe the harness is not connecting tightly. I had a code of P0677 and it was #7 circuit failure. I too replaced all glow plugs. chk engine Light is still on, but I think you have to have the computer cleared.

 

That's definitely the Glow Plug Control Module...you will never see a whole bank of glow plugs suddenly fail at once. Order one off of ebay and save yourself some money.

 

Thanks, I replaced the glow plug control module and all is well. I got the part from powerstroke.com for $126 plus change.

 

Glad you got it fixed!