junkyarddoggie

Hello all, I just joined up to try to to find some quality info. Have this 97 Suburban 4L60E transmission electrical problem. Have searched the web and read hundreds of posts. Some good info. to go on, but mostly BS. There appears to be a million things to check. Ignition switch, power to pin e, pcm, harness, etc etc. But would rather not waste time checking things that don't need to be checked. And replacing parts that don't need to be replaced. First off bought this truck way cheap because of this issue. Previous owner stated truck lost all forward gears suddenly for no reason. Most likely bad transmission one would assume first thing. But this is an electronic transmission and can have all sorts of electrical problems to make it not work. No forward gears but the reverse still works, fluid is clean. After a little playing around. I found that I can turn the shift solenoids on with my scanner, and truck drives normally in all forward gears briefly. Then you have to keep pushing the button on the scanner to keep the solenoids energized. You can't really drive it on the road this way, but I can move it around on my property just fine. To me that kind of proves that there is nothing wrong with the transmission it's self. Scanner is not picking up any codes what so ever. However shorted to voltage says yes in the transmission output control section of the scanner. Short to voltage yes on the solenoid is the only thing that doesn't look normal on the data. If I'm not getting power to the connector from the pcm, how can I tell it to power up with the scanner ? Also If the ignition switch is bad, how am I able to power things up from the scanner ? That leads me to believe that the ignition switch, power wire, and pcm are probably ok. I seem to have power going to the transmission, since am able to control things and view transmission data. I'm thinking it's more like a wiring harness or that control board inside the trans pan. Any other good ideas on this fellas? Thanks

junkyarddoggie

Hey Guys got an update. No Fix, nothing has changed. Not for lack of tring though. Still shorted to volts. I can tell you what's not the problem. Not the pressure manifold, or any of the 6 solenoids, or internal wiring harness. Replaced all electronic parts inside the transmission. Brand new psi manifold. All other parts were robbed from a known good transmission. Guess I'll take the dash apart and look at the ignition wiring next. Go from there. What a pain in the butt this project has turned into. Was kind of hoping to get some leads here. Not even the crackpot, bad temperature sensor guy. I guess I'm the only one ever to have this problem.

junkyarddoggie

Today's Update. Pulled dash panel apart, removed aftermarket sidewinder alarm system, checked all ignition wiring. Wiring was a mess, alarm installer used the twist and pray connection method, which I can not stand. Still no go. Swapped ecu from parts truck I have. Still no go, however no more shorted to volts message. Just for kicks swapped the original ecu back in. What do you know my shorted to volts on the 2-3 solenoids was back. Interesting, but fixes nothing really. Swapped parts truck ecu back in, short to volts is gone. So will suspect original ecu has something going on. Un plugged the big round trans connector and that gives me drive and overdrive by default. No 1 or 2, haven't been able to get 1 or 2 to work no matter what I tried. Thought I originally had those gears working from the trans out put controls. However not been able to move in those gears no matter what I do on the scanner, or anything else I tried.