my truck starts to shake real bad when i hit 45 mph, when i tap the brake or let go of the gas it goes back to normal but when i release the brake or give it gas it starts to shake again. if i leave it in drive it shifts through the first 3 gears flawlessly, but when i have it in overdrive thats when the problems start. it has a 5.7 tbi and a 700r4. does anyone have the wiring diagram for the tourge converter wiring? thanks
CK5
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1990 k5 torque converter lock up problems
- Thread starter p.o.s 78
- Start date
The TCC is controlled by the ECM. If you can drive in OD with throttle and the brake pedal engaged just enough to cancel lockup, then I agree it must be the TCC. If it still does it, then something is wrong with 4th gear in the tranny. Of course you want to check for everything else before ripping the tranny out.
I think there is a way to monitor that output from the diagnostic port(?). I know you can manually engage it via that port. It's possible you have a bad connection somewhere (or a bad ECM) so that the solenoid is not getting enough voltage. Maybe you can string a wire up into the cab and look at it on a voltmeter while you drive. It could also be a bad solenoid. There was an old trick of putting a ball bearing in the snout of the solenoid so lockup happened whenver the valve body called for it. However, I think on the TBI trucks, this would cause lockup all the time, so you couldn't even put it in gear without stalling or peeling out and would be abusive to the TCC and planetary clutches.
I had a shudder like that one time and it was the torque converter. The shop has a machine that engages the clutch with compressed air to see if it works and my old converter wouldn't hold any pressure. New converter solved the problem.
I think there is a way to monitor that output from the diagnostic port(?). I know you can manually engage it via that port. It's possible you have a bad connection somewhere (or a bad ECM) so that the solenoid is not getting enough voltage. Maybe you can string a wire up into the cab and look at it on a voltmeter while you drive. It could also be a bad solenoid. There was an old trick of putting a ball bearing in the snout of the solenoid so lockup happened whenver the valve body called for it. However, I think on the TBI trucks, this would cause lockup all the time, so you couldn't even put it in gear without stalling or peeling out and would be abusive to the TCC and planetary clutches.
I had a shudder like that one time and it was the torque converter. The shop has a machine that engages the clutch with compressed air to see if it works and my old converter wouldn't hold any pressure. New converter solved the problem.
