Does a stock Ecm have any notable lettering on it. Heres why I ask. Took the truck to a friend's tranny shop last week to have tranny rebuilt. It has been on my list of to do's for a while and just scratched up the extra $$$.

He calls me a little while ago, has it all back together, but its having some issues that he thinks aren't tranny caused but are having a direct effect on the tranny. After his first test run, he said that it went into OD no problem. But after a few miles it wouldn't go back into OD. Took it back to the shop, hooked it up to his Snap-on Scanner and gets a error message, basically saying that it could not read the ecm at all. My uncle has the same snap-on scanner and he had the same issue not long after I got the truck.

I can pull codes with the paperclip, like normal. But my friend thinks that I must have and aftermarket ecm that has a hot tune to it. He said that he has driven many 6.5's, and mine has alot more power than any other that he's driven :D. So once I get it, i'm gonna go looking at the ecm.

Or am I missing something? Should I be looking in a different Direction? The tranny didn't shift properly before I took it to him, and I'm getting ready to walk out the door to pick it up. So I will check back in once I get it back.

Thanks Jack

reading on ss diesel site a couple guys may have had similar problems.dude solved it with a wiring fix maybe? may be worth a read.

Oh and the # you are lookin for is inside the ecm on the chip itself. pull it out and undo the torx screw to access the chip

Ok, The # on said ecm is 4206-BMRM-0073, and it is a light blue. Don't know if color says anything about it. I have seen similar on Heaths website, but Have never seen one otherwise. I have never looked at my ecm before, but someone definatly has as it was not remounted properly. It was just kind of laying there, made it real easy to take out though.

My Heath one is light blue. Can't help you on #s though.

The BMRM could be a broadcast code, but there will usually be an 8 digit GM number nearby. Are you saying the ECM case is light blue, or the numbering? The OE parts are plain metal cases. Yes, there will also be a PN on the PROM, which is different from the ECM #.

The # i was referring to is on the chip inside the ecm. After I reread my last post, i saw that I didn't include that part. And that chip is whats light blue. Its not a metal chip, it is plastic. I will find that info on SS diesels site and see if I'm working with the same thing.

The problem I have now is that I just got the truck back from the tranny shop. And it drove it home and shifted fine. I put my new exhaust on it and took it for a test run. Not a hard run by any means. Well, it would start to roll out just fine, but when it tries to shift to second it acts like I have shifted it into neutral. It revs out and won't shift. Just like it would rev if it were in neutral in the driveway.

With scanners not being able to read my ecm, its going to be almost impossible to figure this thing out.

sounds to me as if you have a bad ground wire to the trans.....put a 350 gas in a 93 k3500 that had a 65l in it and we didn't get the ground hooked up and it would hit second and go to neutral.....it was the grounds at the back passenger side head ...they went to the last intake bolt on the 65l...hooked them up and it shifted just fine...


about your chip i couldn't tell ya'll....

PCM (ECM's are for gassers (patooie!)) has a GM-coded p\n label on the case, p\n and cksum code on the chip should be similar - sounds like you need to go thru the re-grounding procedure (with pics for the reading-challenged!) in FAQ's - should give better (and repeatable!) results

Truckie, let us know if you figure out if you have an aftermarket chip from SS or Heath or wherever. I'm considering getting one from one or the other (price is close on both) but would like some feedback from people as to what they've experienced and is it worth the almost 4 hundy for it? Already have the intake and exhaust mods that are recommended and am also going to order gauges if the chip is worth it. My 94 like yours can only get the chip and not reflashed so I'd really like to hear some comments from you guys, thanks, Mike.

The Snap On Brick scanner that I tried to hook to my truck wouldn't read either. Came up with an error. Wonder why?

I don't know why, it sounds like the same two scanners that have been attached to mine. I'm gonna bring the old girl in and give the grounds a whoopin. Then hopefully for an improved test run.
:rotflmao:

Well, i'm gonna have to call it a night. The stuff to clean the grounds that I would normally have on my truck were unloaded to go to the shop. And I am at the firehouse tonight. So I am SOL. :mad:

And to top it off, it will not shift into 2nd anymore. So its gonna have to sit here until tommorow when I can have it towed. Its just frustrating to put big $$$ into a rebuild, just to have it S&^t out on me. Okay vent over. Once I can confirm clean grounds, i'll start back at square one.

I am almost positive that is a stock chip you have there. other examples are bprx bpaa, heath puts his own decal on his chip. If you want a definite answer, call heath's toll free line, them guys are always happy to answer any question I have had. Great service.

The Snap On Brick scanner that I tried to hook to my truck wouldn't read either. Came up with an error. Wonder why?


Are you using GM OBD-I cartridge and if OBD-I do you have the correct plug for GM, & cigarette plug for power into that ???

Hey Doc, To be honest with you I'm not sure about either of those questions. I personally haven't tried to hook the scanners up. Both of the guys who owned them did. Now, both have experience with working on older vehicles, so I would think that they would have had the right plugs and such, but I will put a call into the tranny man today to make sure that he had it all set up right.

I can do the paperclip method for pulling codes no problem. Right now it just gives me 12 because I had the battery disconnected when I put the new exhaust in.

Jack -

I replaced my PROM last Fall - OEM ACDelco from the local Chevy house. It's light blue, GM part# 16244781stamped on it. My PCM is an ACDelco reman unit, ACDelco part #88961136, GM part #88961136. Hope this helps!

Dave

Hey Dave, Thanks for the info, I am starting to think that I have a stock setup. What caused you to change out your PCM and Prom?

I've been thinking about all of the problems that I've had for a while on my truck. And it dawned on me that another consistant issue that I have is my wastegate solinoid for some reason isn't allowing vacuum to the wastegate.

When I got the truck, the vacuum pump was shot. Replace it, and still no vac. to the wastegate. Replace Solinoid, Nothing. Replace Boost Sensor, still nothing. So since then have had the vacuum line directly from the pump to the solinoid. I know, I know......not the way to correct it. But I never boot it and have never towed with it. I've never had it throw a code for overboost. So with all of the boost related parts replaced and still no resolve for it, I put it lower on the list of fixes that I had. And up until now haven't really thought about it.

I'm really starting to think that the PCM is causing the problems across the board.

2wd 4L80E not same number as 4wd 4L80E or 4wd NV4500

Hey Dave, Thanks for the info, I am starting to think that I have a stock setup. What caused you to change out your PCM and Prom?

Actually, I only had to change the PROM. In '94, there were two IP's used - one for light duty; one for heavy duty. Each pump had its own PROM chip. Trying to team an IP with the wrong chip resulted in all kinds of running/performance problems. When I bought my 1Ton dually (not running/partially disassembled), it had the LD pump, but an HD chip was installed in the PCM. Since the LD pump was actually the stronger/more reliable of the two, I decided to switch chips ($85) instead of pumps ($$$$).