96 7.3 turbo. Van won't start. No Ficm voltage shows using android apps and scanner. Will not buzz test unless I supply main power to Idm. When not supplied with jumper, main power only shows voltage for a second when key is first turned on. My guess is no signal from pcm on Idm enable wire which go to Idm relay in fuse box. What besides a bad pcm would cause it not to enable? Wait to start light stays lit even when glow plugs relay kicks off. Any help is appreciated.

 

No PCM/IDM DTCs?

As a quick check,, using a test light on the IPR connector (red wire) is there contionous voltage there with the key On? The PCM controls the IDM relays ground for closing the contacts. You could check for a PCM supplied ground on the relay connector with the relay removed.. Both active?

 

Both red wires to pcm has power with key on. Pins 71 and 92...vpwr. Ipr is on same wire and had power last time checked. Only DTC was 1668..I think...no communication between pcm and Idm when I tried to buzz test. With Idm jumped over...the DTC doesn't show and will buzz test.

 

It turns out that the PCM is a DPC-315 and the Chassis Harness is for a DPC-202. Will be ordering the right PCM later today. Will update if it fixes my problem.

 

The new dpc-202 pcm fixed the problem. The van is starting and running fine. A pcm made for a 1997 will not work with 1996 wiring harness.