Hi all new to this site and hopeing to get a little help. I searched this code on here already and have read tons of info, but so far nothing has helped.

Here is the situation..... I have a 98 Yukon 4x4 with the 5.7 vortec and around 125000 miles on it. About 2 weeks ago I was on my way home and the MIL came on. I work for Auto Zone so I borrowed out scanner and got a p0758 code. I not really paying attention to what the code actually said replaced the 1-2 and 2-3 solenoids, and also the 3-2 down shift solenoid. Still had the same problem.

I google searched the problem and found this site. I ready up and checked everything I have the power check. I checked for power at fuse 20 (ignition switch problem) and there was power there. I then pulled the pan (again) and checked for power at the solenoid, and there is power there. So I know my internal trans harness is good (checked it out extra carefully). I know I have power going to it. I know the solenoids are good (checked the new ones and the old ones).

So my question is where should I turn next. Is it possible the computer is bad? If so I cant find a listing for the trans computer. Is it the same computer that controls the engine? If so is there any way I can test this item? Any help is greatly appreciated as this is my tow vehicle and I have an offroad event coming up the end of the month and need it badly. Unfortunatly with high gas prices I cant afford to pay a shop to fix it and make my event.

No help on this one? I was just wondering if anyone knew anything else to check before I go and replace the ecm? Any help would be greatly appreciated.

Using a full mode trans scanner you can command and confirm these solenoids for proper function, this is the right way to diagnose the problem source. This is an open or short in the Solenoid B circuit do some continuity tests also.

I have checked the hot side all the way to the solenoid. No problems there. I have power at the plug for the solenoid. I dont have access to a scanner that can do the testing where is forces a shift. I dont have enough money to take it to the trans shop either.

Do you have any idea what color wire the ground is coming from the computer so I can at least do a continuity test on that? Any other ways to test this out without the scanner? Is there a way to test the ECM? Also is the engine computer on this truck the same one that controls the transmission? Thank you for your response.

Yes the pcm also controls the trans shifting, you are going to have to get lucky to do this on your own, you will need at least a wiring diagram here to look for an open or gd in the pcm side of the circuit from the solenoid to the pcm. 3-2 is a white wire to the pcm, 2-3 is yellow/blk, and 1-2 is light green.

Thank you much. I will check for continuity on those wires from ecm to the trans harness.

If I have continuity on those wires all the way to the shift solenoids that would pretty much mean that the ecm is bad correct?

Well again, only a bidirectional trans scanner that can command the solenoids thru the pcm will really tell you the story.

Any idea what a shop would charge to test that out for me? I am on a really tight budget and need this fixed in the next couple of weeks. I have a 4x4 event coming up, and that is my only vehicle capable of towing my trailer and comp rig.

We charge about 60.00 for a scan of that type with a road test, upstate NY. This type of scanner is usually only used by a full line trans shop or a dealer.

Thank you for the info. I was thinking it would be more than that. I tried calling around and all the shops here just want to rebuild it because it is over 100,000 miles on it. I will try and just take it to one of them and tell them to run that scan. Thank you very much.