'98 RCSB K1500 going into limp mode

[LSUfan71]

From another thread:
http://www.gmt400.com/forum/showthread.php?26918-Need-help!!!-Currently-in-limp-mode-4l60e&p=786686&viewfull=1#post786686

Any luck on this? Sorry if this is late. On that code, if you have already replaced the shift sol, it could be a couple of things. One is voltage, but you have covered that. Second is the PCM or wiring. The PCM sends one wire to the "B" solenoid. It sends ground to turn that solenoid on. If the PCM is bad, it won't send that ground and you have failsafe. If that wire is broken or shorted, you will get that code. What I would do is run a new wire from the PCM to the Transmission connector. Should take 20 minutes and that will determine if the problem is in the wires or PCM. I have the pin numbers on the PCM and Trans if you want to try this.

@rhino, can you send me that info? This really seems to describe the problem with my truck.

Anyone, forgive my wording & terminology, I'm not a tranny guy:

When my truck is cold it will start off in 1st fine, I'll have 2-3, it really drives fine while I'm trying to get out of my subdivision to the highway. The problem begins as soon as the engine warms; it will start from a stop in 3rd, I'll have 1st or 2nd manually. Occasionally from 3rd it will go into 4th (I think) when I get it to about 2600-2700 rpm.

My transmission shop replaced both solenoids and valve body, still same problem. Transmission guy at the shop says I should replace the computer. He "thinks it should" fix the problem. They had it 3 weeks and this is where they were, no improvement, so I just took it home so I can get it done myself or somewhere else; lost my patience with them. They could have handmade another transmission in 3 weeks.

Anyway, another issue is that the wiring harness was allowed by previous owner to come to rest on the EGR tube. The plastic conduit melted at that location, of course, so I had copper strands in one wire exposed due to the heat with a few broken threads and I repaired it. A few other wires had some discoloration due to heat but no apparent physical damage. The guy at the shop says the wiring is fine (not that I put confidence in that determination).

I ordered a reman ACDelco ECM and it came in yesterday but I haven't had the chance to go somewhere to get it flashed, been working all week. I'm about to leave work in a few minutes and I'll pass a Pull-A-Part location so I think I'll stop and grab a cheaper ECM for experimentation I suppose. I may have the ECM from Pull-A-Part flashed and if it works fine then I guess I can return the other one and save $180 bucks.

I've owned this truck for about 6 weeks and I knew it had tranny problems but I got a deal on it, so I have patience for the truck but not for the tranny shop.

Advice for a tranny newbie? (it might be Monday before I can get a computer flashed)

 

[LSUfan71]

Anybody?

Sitting at a dealership right now waiting for the ECM to be flashed. They quoted me $115 for the flash then hinted at an installation fee. Told them I could handle that. Wondering if they'll insist on the install fee... >:

 

[df2x4]

Sorry I'm not any actual help here, but I just had to say those PCM prices are outrageous. $180 just for the part?? You can buy used, tested cores from BBP for like $50. When you consider the stealership price for flashing and installing your new one, you could have had a custom tune made up for your truck from BBP and still been money ahead with better results and a spare PCM. $115 plus install (easiest thing ever, move one bar and disconnect/reconnect 5 harnesses) for a stock flash is straight up robbery IMO.

 

[LSUfan71]

$115 plus install (easiest thing ever, move one bar and disconnect/reconnect 5 harnesses) for a stock flash is straight up robbery IMO.

That's what I was afraid of. I had ordered a reman PCM from ACDelco via Amazon. But I had the dealership flash the one I yanked at Pull-A-Part; they said it flashed but would not clear anti-theft. So the reman unit was flashed and installed, my tranny problems cleared up and it seems to be running perfect now. Cost me about $125. They didn't mention an install fee again after I told them I was quoted a price over the phone.

The service rep at the dealership specifically said that PCM 'must' be installed in the truck in order to finish the flash/anti-theft. I obviously am not armed with enough experience/knowledge to challenge him. I suppose that the anti-theft stuff must be disabled in order for a flash to be done with the PCM out of the truck?

 

[LSUfan71]

And they refused to flash anything other than factory settings.

I may later try another service but I was in a hurry to get this truck on the road.

 

[df2x4]

Hey, if it fixed your trans problems then that's not such a bad deal! I always forget about the Passlock system, that's probably why it cost you so much. Got to do the security relearn with the new PCM in the vehicle. They only started doing that from '98 up if I recall correctly, both of my trucks are '97s so I never had to worry about that.

 

[LSUfan71]

Well, considering I was prepared for a $1,800-$2,400 rebuild, I'm actually very pleased I came out that cheap.

 

[LSUfan71]

I snapped this pic of a 2016 Z28. Just for eye candy...

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