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Transmission slipping

i have an 01 sonoma and my transmission started slipping pretty bad, so i went ahead and replaced the transmission, problem is…the new transmission slips exactly the same as the other one…any clue on the problem??

Did you swap the transmission with a new one, a rebuilt one, or a used (Junkyard) trans?? Has anyone done any troubleshooting with the trans?? For instance, Checked line pressures, and scanned the computer?? If not, that would be the place to start.


it was a brand new transmission…i got a diagnostic check on my truck a long time ago and it was reading a crankshaft a sensor was out…but i just ignored it, the people wanted me to buy one for 90 dollars and i just didn’t have the money…could that be cause the slipping?

Crank sensor?? No. TPS (Throttle Position Sensor) maybe. Pressure control solenoid?? Maybe. This is where a pressure guage and scanner come in. What I usually do is connect my scanner to the computer and a pressure guage to the line pressure tap. Using the scanner, I take control of the pressure control solenoid and adjust its current through the scale while watching the line pressure. If its within specs, its usually good. I also check the TPS with the scanner to see if it is operating properly. The TPS is what controls the pressure control solenoid. You need to get this trans looked at before the slipping destroys it which might void the warranty on it.


ok. i had someone else tell me it might be a pressure problem as well…but what about modules, just to get your professional opinion…do they cause slipping as well? because i’ve had a couple of people tell me it might be a module

You mean the PCM?? (Powertrain control module) Maybe since it processes the information. Let me tell you something though. DONT go throwing parts at it, this could get very expensive. Someone needs to troubleshoot this transmission and narrow the problem down.


ok well thank you very much charles, you obviously know a lot about this stuff… i’m from the bakersfield area in cali, hard to find people that really know what they’re talking about here, wish you hadn’t moved away from the west coast :wink: but thank you very much you’ve saved me a lot of money and headache

[f] … got a diagnostic check on my truck a long time ago and it was reading a crankshaft a sensor was out…but i just ignored it [/f]

Of course if a new error was triggered by the transmission problem, you would have no way of knowing about it since as far as you would know it was just the crankshaft sensor.

When you do find out about it, follow up with us on the forum. Let us know what you find out.