View Full Version : Engine Control Module

Dave L
11-24-2007, 07:14 AM
My '95 D90 SW won't start. I can hear that the fuel pump is not working, and the local mechanic tells me that it's the Engine Control Module (AMR3947) that's bad. If they put power right to the fuel pump, it runs fine. The dealership tells me they can special order a new ECM for ~$2200! Quite proud. Has anybody used any of the refurbished ECMs? Can anyone recommend a source for a used/refurbished one?

11-24-2007, 03:30 PM
before i replace the ECM i would check the fuse,relay operation and wiring,also the ground, then check output of the ECM right at the ECM .....

Dave L
11-26-2007, 12:54 PM
Yeah, they tell me they have done all that. Said the ECM won't turn the fuel pump on and will only tell an injector to fire once every few attempts. Sound reasonable? Do you know of any source for a used ECM or a reputable source for a refurbished one? ecudirect will sell me a refurbished one for ~$680, but of course won't take it back if it doesn't fix the truck.

11-26-2007, 05:09 PM
i have a few opt's octagon spares 717-244-5279,lkq 800-626-6708, linders 800-521-8000 if none of these work out try DAP www.dap-inc.com or your local parts store a lot of ecm's are available in the aftermarket world today if all these fail spend the $680.....

12-06-2007, 10:51 AM
I'm having similar problems I've been told it's probably the ECU but i have yet to find the right replacement.

12-07-2007, 06:03 AM
If it's an NAS 90 with 3.9, it will run fine with any 14CU or CUX ECU from pre '96 Disco, 89-95 classic. There are so many of these old trucks being scraped, used ECU are easy to get. PM if you can't find one. I have a few and know of another source also.
As some one previously said, check the relay and crash switch first.

12-08-2007, 12:22 PM
How do you test the relay? I now exactly where it is just not sure the right procedure

12-24-2007, 07:14 PM
Did you check the fuel pump relay? Try Roversdownsouth.com for a used ecm

Dave L
01-03-2008, 08:11 PM
You were right - it wasn't the ECM, it was the relay that led to it - thanks. Of course, the mech didn't find it until the bazzilionth time checking it. It wasn't fully engaging, so the ECM was getting voltage - just not enough! Of course, I now have a spare rebuilt ECM...
Thanks guys,

01-14-2008, 07:06 PM
Which Relay was it? I know there are two. They both are clicking and seem to be working for me, but I'm not certain they are 100%. It doesn't appear to be the ECM. The ignition coil is getting no spark, could this be a sign of a bad relay, or just a bad coil? Hope someone can provide some insight.