Hello everyone,
Trying to diagnose a 97 E350 ambulance for a"miss under load", the customer has replaced IDM, glow plug relay, and valve cover gaskets. I have noticed that when you first key on the glow plug relay comes on then acts as if it is shorted or has loose connections, the service engine light comes on then goes off within 1/2 a second. Tried using scan tool and I have found I have limited communication with the vehicle, I can only perform tests in the IDM can not communicate with PCM. Truck runs and drives ok other than the intermittent miss or stumble. With the glow plug relay connected if you remove PCM relay the IDM relay clicks rapidly unless you disconnect the signal wires from glow plug relay. Wondering if i have a pcm issue? Anyone have this problem before? Any help would be great and thank you in advance.