Where is the 4th gear pressure switch. Trying to fix lockup in 4th problem.

[Nasty Wendy]

Hellow. I have a problem with the tranny. My TCC won't lock up until 55mph in 4th gear. The chip(s) that I have call for loock up at 45 in 3rd and 4th gear. If I put the car in D my TC locks up at 45mph but in OD it won't lock up until 55mph. I changed what I think is the 4th gear press switch, I saw two switches when I dropped the pan and I changed the one closest to the front of the car on the passenger side of the tranny guts. This didn't fix the problem. The TC still wont lock until 55mph in 4th. I've tried 5 chips. Any and all help would be greatly appreciated. TIA.

 

[Stephen Soulsby]

Yes you replaced the right switch. Here is an easy way to check the switch without dropping the pan. Get a $3 test light from your local auto parts store. Jack up the rear wheels off the ground and support the rear axle securely with jackstands with the front wheels chocked. Safety is everything. Check for a ground signal in hte top right (fourth gear switch) wire and bottom right (third gear switch) wire coming from the drivers side of the trans. If you do not have ground, replace the faulty switches. If you do have ground start the motor and put shifter in D (third). With your hand, accelerate the car until it is in third gear (you'll feel a clunk every time it shifts). When it gets to third gear, the bottom right wire should not have any ground signal. If it does, replace the switch. Next put the car in OD (fourth). Accelerate the motor until the car goes into fourth. The top right wire should loose ground when it goes into fourth. If it doesn't, replace the switch.

Let me know if everything checks out. My converter won't lock at all right now and I stil have more things to check.

 

[Nasty Wendy]

how bout' this.

What if I tapped the 3rd and 4th gear wires and ran extentions to the inside of the car. Now I can hook my aligator clips to them and two multimeters and check out what happens when I drive. I don't like the idea of the car on jackstand running in 3/4th gear with me underneath. I do like the testing of the switches tho.

What kind of crap could cause the cpu to not know the tranny is in 4th until 55mph especially if I changed the press switch.

Thanks for the advice Stephen, it was responsible for my next conkocted test.

 

[Stephen Soulsby]

That would work as well. Just make sure they're secure and won't come off while you're driving. As for the ECM not recognizing it's in OD until 55, only one other thing I can think of can cause that problem is a bad vehicle speed sensor. Check for a trouble code 24, but it probably won't be there because it would be a weak sensor, not an outright bad one that the computer would see. If the pressure switches test good, replace the vehicle speed sensor located on the back of the speedometer. Probably run about $40? Specify to the parts guy if you have the digital guages or not.

I now got my TCC working today. Bad solenoid. Only had 2 ohms. New one has 25 ohms.

Let me know what you find.

 

[Nasty Wendy]

Bad VSS

A bad VSS, now I never thought of that. I guess I figured it to be good because I have lockup in third at the proper speed and the scanmystery shows my MPH and doesn't show a trouble code. I've tried everything else and can't seem to pluck this gremlin-tick off of my ass. I'll try another VSS and see if that works. I'll keep you posted.