If my overdrive is not engaging, does this mean my TC is not locking up?

Ive seen a few posts on here suggesting installing a lock-up or "mystery switch". If I do this, will my OD work when I flip the switch or what?

Can someone explain that to me?

Also, any detailed instructions on how to do this to a 1997 12v would be GREAT.

Ive searched and searched for days on the various problems ive been having and the searching has given me a headache so any help would be much appreciated.

 

If you lock out OD does the TC lock up in third? TC lockup and shifting into OD shouldn't affect each other, you may be having a sensor problem of some kind. The Mystery switch simply allows you to keep the TC locked up whenever you want, with it turned off the transmission should operate normally.

 

crap im having other issues then i guess.

My trans wont go from 3 to 4.

and it goes from 1 to 2 very quickly and my rpms are really high.

It used to kick into 4th around 45mph and the RPM would drop a lot, but now it sticks in 3rd and I top out at 55 at almost 2500rpm and basically floored.

I was hoping the switch would force it to go into 4th(od?)

 

A switch is cheap and easy, just do it
Instructions> http://www.tstproducts.com/Torque%20...p%20Switch.pdf

 

infidel-

Will the switch cure the problem I am having?

If so ill hook it up tomorrow!

 

Bet it is not 4th, but TC lockup you have lost.

4th is small RPM drop vs. the TC lockup.

You don't want to hear this, but when mine pulled that stunt, my TC linings were shot.

 

you've got trans problems, nothing big but there are a couple sensors and one might have gone bad.

 

its really disspointing to hear that.

The trans was rebuilt 4k miles ago and is now out of warranty, not because of miles but because of time.

Any suggestions?

 

No, it might just mask it, but it will help diagnose what really is wrong.

 

TPS is my guess. They typically get dirty and stop responding. You can try to clean them and it works short term, but eventually you need a new one.

 

You know...I hooked up my OBDII scanner to it and it pulled a P0123 "TPS Circuit A voltage high." so Im guessing that its the TPS also.

I guess I will try replacing the TPS this weekend. **** things are $170 bucks and a special order 2-4 day shipping

 

the tps voltage can be adjusted - google for it. You may save yourself some bucks...

 

Search up TPS cleaning. There was a good thread a few years back with pictures and dimensions for drilling a hole in the casing. Hitting with some good electrical cleaner and resetting for the proper voltages may help until you want to splurge on the new one.

 

First you need to figure out of your problem is OD or CL. You can do this by driving the truck with the OD switch on(light on). You should feel the 1,2,3 shift and then the CL. If you don't get the CL the converter lock is the problem and not OD. If you don't get CL hit the OD button (light off) and see if it shifts up. If it does the OD is good and your problem is in the CL (there will be a slight delay before it shifts, this is programmed into the computer to unlock the converter before the shift to reduce stress on the flex plate and input shaft).

I bet your problem is the OD solenoid on the valve body. I have seen this a few times. the solenoid is a coil of fine wire. It has a plastic shield clipped around it but the wires are still exposed. the wires that connect to the terminals will break lose at the joint. the wire usually is hanging out below the shield when this happens and one turn can be unwound from the coil, insulation cleaned and soldered to the terminal and it will work.

You can test for this before you drop the pan. Wire a test light to the converter lock wire as it enters the tranny. I think it was the rear most wire in the tranny plug. Run a wire from there into the cab and hook to a light. Run the other side of the light to 12v and go for a drive. If the light comes on at 45-50MPH and the converter does not lock the solenoid is bad. This test also works on the OD solenoid but you connect to the front wire. The solenoids are the same.

I have seen many times where people put the filter on and pinch the wires. The insulation usually prevents a short but I have seen some very flat wires where I was surprised it did not short. If this was the case OD or CL would stay in all the time or blow a fuse if it was the third wire.

 

dguru, you could also have a case where the TC clutch linings have shed, and electrically, it looked like the Solenoid was bad.

A easy way to check it is to jack the truck up on stands ( or command TC LU with a DRB3 ) and have someone feel the rubber trans cooler hose up by the radiator. When TC lockup is commanded you will feel a definate pulse in the hose if the Solenoid is working.

That's how I finally diagnosed my bad TC.