Chevy Silverado Transmission And Shift Indicator Problem

Question:
1997 Chevy 1500 Silverado 5.7L Service Engine Soon. I was pulling out out of car wash yesterday. I noticed my P,R,N,D,3,2,1 indicator light was off, (could not read which gear), my tach wasn't moving, and lost my Speedo too. Had VERY minimal power in drive gear. (I could tell I was in drive from feeling). Felt complete loss of power. Drove it 1 mile to service center. They put a scanner on it, it's throwing following codes: Torque Converter PWM, PWM Solenoid. Clutch Solenoid. 1&2 shift Solenoid, 2-3 Solenoid. Dipstick for trans has bubbles, which could mean low fluid, but they say fluid level is fine. This morning, they want to pull the transmission pan to check for shavings, and to look at solenoids. This service center is not my usual mechanic. Went on 1 mile test drive, vehicle would only go in drive, and could only accelerate in 1st, then mechanic would shift up to Drive gear, but was moving slow. My mechanic who I’ve known and trusted for 20 yrs is in another city. He suggests topping fluids first!

Then looking at pan, he said based on the codes that are being thrown, it sounds internal. He also knows how I baby this truck. He also said if FLUID IS LOW, that it could throw all those codes previously mentioned above once topped off, codes could go off, and restore normal driving. (not sure if matters),but I NEVER haul, or pull anything with truck. This truck is pampered, daily driver, driven like an old ladies car. 181,000 miles, (orig engine trannie) and runs fantastic, which is why I was so surprised this occurred yesterday. PRIOR to this occurring, I’ve had no symptoms, no shakes, no stalling, no grinding of any sort. ALL maintenance done routinely, has been a wonderful truck, given me NO problems in last 8yrs. (i don't know if you guys call, but if so, let me know and i will supply my number) Thank you !!

Answer:
The transmission fluid being low would not cause any of these codes. Bubbles on the transmission dipstick are probably caused by the way it is running. With the shift indicator light being off, tachometer not moving, speedometer not working and all the transmission codes you have, this sounds like electrical problem.

It's possible you have a bad ignition switch. The ignition switch is what feeds power to most of your truck systems including the transmission. There is a pink wire that goes down to the transmission Her. It should be hot. This wire feeds all the solenoids inside the trans. It also feeds the transmission range switch, known as the PRNDL. First check all of your fuses. If the fuse is blown for the power feed to the transmission solenoids this can cause all your problems.

The reason the truck doesn't run well is because the computer doesn't know what gear the transmission is in. I would not worry about taking the trans pan down now to you get this electrical problem fixed. Any transmission with 181,000 miles on it is going to have debris in the bottom of the pan. But this is not the cause of your problems.

The next step would be to use a test light and check for power at that wire at the transmission. If there is no power you're going to need to trace that wire up to find a broken wire. If there is power there then you would need to go into the transmission and check all the solenoids. If one is shorted it will affect the whole circuit and all other shift solenoids.

VISITOR REPLY:
Greetings and thank you very much for your reply!! I apologize for my late response to you. This is my work email, and have been extremely busy. Your analysis is dead on what my own personal mechanic said. I took the truck to him the day after I wrote to you guys, and he put a diagnostic tool on the ignition switch and noticed it wasn’t running enough amps. I believe he said should be running 15 amps, and was only doing 3.

After that, he pulled the trannie pan, and did not see anything bad. He added all new trannie fluid and a filter, slapped it back together and it has ran good ever since. We think what happened was the FIRST SHOP I took it too tried to pull the “metal shavings in the pan “ scam that is seemingly prevalent with shady mechanics. They put some metal shavings in my pan, called me back to the shop, showed me the pan full of shavings, and tried to convince me to spend $2,400 for a re-manufactured trannie. I took a picture of it.

I had it towed to my mechanic, & the Truck has ran completely fine since my own personal mechanic looked at it. I intend to turn the other shop into the better business bureau, but not before I confront them about what they tried to do. Plus, I would like to have them REFUND my $125.00 for the diagnostic they charged too.

The only thing the truck has done since this occurrence is stall 2-3 times in traffic, which could also be “Electrical related” . When it does that, I shift to Neutral, start it back up, and keep going.

Ignition switch is approx $200 at O’Reilly’s, should be a simple fix. Thank you guys again for being available. REALLY appreciate your knowledge! God Bless.