I dont have that on my chip.

 

Im at a complete loss here. I found a random schematic saying how to check the FDCS voltage between the IDM and the PCM, but it requires a break out box, which doesnt seem to exist. But when i get off work i will be ohming out pin 96 and 91 on the PCM. And if that doesnt come up wrong, I am completely at a loss. Also it did crank with ether (I hated using it but I had to see) but immediately died.

 

Stupid question but I'll ask. Does the IDM have power?
Have you checked the IDM fuse in the engine compartment? Also the IDM relay which is in the same box as the fuses. To verify you can swap the horn relay with the IDM relay. Still sounds like a dead IDM or no power to it..

 

I have swapped in all fuses and moved all the relays back and forth in every configuration I can imagine. I am actually going to pick up another 30 amp fuse and a brand new relay this afternoon. Im willing to try just about anything

 

but... when i do crank the motor or try the buzz test, there is no clicking from the Relay

So could that mean its a power in thing and maybe a problem with the fuse box? I was under the impression the signal from PCM to IDM then activates relay to power injectors...

 

Operation is pretty simple. Key ON the PCM relay is energized. One of the contacts on the PCM relay supplies power to the IDM relay coil so it also is energized. Believe the fuse is either #8 or #9, 30 Amp that supplies power and protects the IDM.

If you don't already have this link it's a good diagram on the fuse box.

Go to Electrical distribution ... Wiring and Circuit Protection ... Power Distribution Box.

https://www.thedieselstop.com/faq/94...an/stjmain.htm

 

No, see post above. When PCM relay is pulled in the IDM should also be pulled in supping power to the IDM always, until you turn the key OFF. There is no relay clicking and the buzz test is done electronically through software as is the firing of the injectors.

 

Gotcha. Yeah i love that manual. Has helped me tons. I have checked all of those fuses and relays multiple times. But 30 bucks is still a lot less then 700 so I will pick up new fuses and relays just to be sure. anyone by chance have the ford part number for the relay? Im not at home right now and I cant remember

 

Also try to start with the chip out if not tried, with new IDM.

 

went through all fuses again. all relays. tried new idm with chip, without chip. Tried old idm with chip, and without chip. Found some instructions on how to check the resistance on PCM, but cant find a pic that shows me which one is 95, 96,48 and 91. You guys have any ideas? All help is greatly appreciated.

 

So this was my last thing I could think of. I tested the resistance on the PCM between pins 91 and 95, 91 and 96 and 91 and 48 and all of them had way over 1000. 91 and 95 barely registering at setting 25m on my multimeter. ohmed out the harness to idm. All at 000. Then plugged ECM back in, and checked the power pin on the IDM Harness, number 17 and number 4 and never got any volts. With key in ignition, while trying to turn over, nothing. I checked voltage at all fuses and coming into all relays. Without a break out box, im not sure what I did with the idm harness works or not, but Im feeling pretty confident that the IDM is getting no voltage. The question is, does that leave my working for everything else PCM as the culprit??

 

Well, now I feel like a total jerk . Was going from memory but did take a look at the schematics today.

PCM relay does supply power to the IDM relay coil but the ground side of the IDM relay coil goes to pin 70 on the PCM. That pin does ground the IDM relay to activate it.
Power input to the IDM is on pin 14 on the IDM thru the IDM relay. Guess you could measure it there.

So yes, that one bad pin #70 on the PCM or internal damage would prevent the IDM from activating. I would check out pin #70 on the PCM for bent or damage pins before ordering a new PCM though.

 

No worries buddy. You have been amazingly helpful. All pins look perfect. So, kinda wondering, is PIN 70 just a ground? think there may be a way to splice that to another wire and just ground that circuit permanently? Or would that just not work at all and mess up the IDM? Im guessing im gonna just have to buy a PCM. Sucks because there appear to be none available from the auto stores (all on back order) and the only place i can find is Flagship and they want 550 bucks. Any suggestions are greatly appreciated or other ideas. Because im at a complete loss now.

 

[QUOTE=muscle66;18623790]No worries buddy. You have been amazingly helpful. All pins look perfect. So, kinda wondering, is PIN 70 just a ground? think there may be a way to splice that to another wire and just ground that circuit permanently? Or would that just not work at all and mess up the IDM? Im guessing im gonna just have to buy a PCM. Sucks because there appear to be none available from the auto stores (all on back order) and the only place i can find is Flagship and they want 550 bucks. Any suggestions are greatly appreciated or other ideas. Because im at a complete loss now.[/QUOTE


I got my spare pcm from e bay years ago. I just looked over there and wow they have gone up in price.

 

I don't know if pin 70 is an actual ground on the PCM or if the PCM grounds that wire internally (electronically). The only reason I can think it is there is to disable the IDM relay and power to the IDM in case the PCM is removed or unplugged. The schematic label just says "IDM Enable Out". I really don't think it would hurt anything just to ground Pin #70 and see if the IDM powers up. But that's just me and I don't like suggesting something that I've never tried. I know both relays PCM and IDM activate pretty much simultaneous as far as I can tell so I can't see any reason for a delay.