ECM question

Horton · #1 10-04-2009, 07:48 PM

I was trying to read ECM #s that Landyacht318 talked about. I removed the cover held by the torxhead screws, here is what I could see. A heat sink in the center, a circuit board covered by a soft foggy gel. The gel is cracked all over the surface. I didn't try to remove anything other than the wire harness that bolts to the top of the computer case. There are no readable numbers inside the case, am I looking at the right part? The shop replaced the idle speed control motor, so the van runs correctly now. I asked them to look for numbers on the tranny case, they said they found no numbers. They did say they drove it and got no error codes, but code 35 is still on the key dance. Can I clear this by unhooking the battery?

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landyacht318 · #2 10-04-2009, 11:11 PM

Hope I didn't send you on the proverbial goose chase looking for a number. As far as the cracked foggy gel over the circuit board, it is the same as mine, but mine has 2 circuit boards, one on top of the other each encased in the silicone. The number was on the bottom circuit board, whose gel was less foggy or cracked. I see your ECM only has one 60 pin connector, and probably only one circuit board.

I was under the impression that every ECM had a number written on the circuit board somewhere, as I've seen it refered to on other forums for dodges and other makes.

Try wiping off the accumulated grime off the silicone without flooding the cracks, with any liquid. There is an outside temp sensor in there that requires ventilation so it gets dirty and might just be obscuring the number. It is in the gel if it is there.

But if it is cracked, dirty and foggy, it is probably the original computer, and my hypothesis is no longer valid.

The shop should have reset the codes, but you can do so by disconnecting the battery for a while.

Horton · #3 10-04-2009, 11:47 PM

Okay this helps a lot. I just didn't want to mess with the gel & screw things up. I think I can assume it's the original from what you've described. Thanks Landyacht.

landyacht318 · #4 10-05-2009, 08:34 PM

There remains the possibility that the original computer was swapped out with an equal age junkyard computer that was for a 3 speed instead of a 4.

Horton · #5 10-06-2009, 12:38 AM

Very good point LY. My next stop will be the tranny shop recommended by the guys who fixed the idle control motor. I need to call them to see if they can run a scan while driving the van, to see if the computer calls for OD to engage. The fan clutch was bad also, they fixed that last week. If the computer is bad, do the rebuilt ones have to be reprogrammed? If not I can check rockauto. I'm not quite ready to replace this one until I've exhausted the other possibilities.

landyacht318 · #6 10-06-2009, 02:44 AM

I don't know for sure on your '90, but my '89 did not need any programming. It works right from the box.

Rockauto is pretty good about taking stuff back, your only out the cost of shipping. Might be cheaper than going to a tranny shop.

There should be a way to manually engage the overdrive solenoid. I don't know it, but it would be a good way to determine if it is a mechanical or electrical issue.