mystery switch

[SRehberg]

I just tried the "mystery switch" per TST's website on my '96 auto, to try to determine if my torque converter lockup/unlock problem was electrical or mechanical. What I experienced was this: I could lock the TC in 2nd, but not in 3rd or OD. Once locked in 2nd, it would stay though. When I turned the switch off, it still stayed locked and was quite an eye opener when I tried to stop; similar to not pushing in the clutch when coming to a stop.



Anyone else had this problem with the switch? Thanks in advance,



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'96 auto completely stock, except line pressure tweak.

 

[Joe G.]

It sounds like you used the instructions for wiring the switch for the '94 and '95 models. In '96 the circuit is different because there is a relay involved. The relay must be removed and a jumper wire installed in the socket.



The wiring diagram for the switch at the TST site is not the best way to go. In order to avoid damaging your TCC you have to provide a way to force it to UNLOCK under a hard pull or excelleration. I've wired mine with a single throw double throw with center off switch so that when the switch is up the forced lock is on, center the forced unlock is on, and down is stock behavior. This is done by cutting the wire TST says not to cut. Then connect the wire to the transmission to the center pole, the ground to one of the outside poles, and the wire to the CPM to the other outside pole. I also have the ground wire connected to a dome light switch mounted on a brack on the floor where an old fashioned dimmer switch would be. This allows me to quickly unlock the TCC when it is force locked so I can stop or down shift easily and then reconnect the forced lock.

 

[SRehberg]

I removed the relay per TST's directions, installed the jumper which puts a constant 12V to the solenoid in the trans. Then the computer or the switch provides the negative side for operation. When this thing started bucking like someone forgot to push the clutch in, the switch had already been turned off, at approx. 35mph. I know the TST site says for all '96's up, except Calif. trucks, (which this one is) so I wrote TST and they replied it would set a "chech engine" light. That didn't bother me much, and I didn't see that happen; just wacko behavior. Needless to say, I didn't try that one again and the switch is now on my work bench thinking it over.



How do you force the TC to unlock other than disconnect the ground to it?



Thanks for the reply; I may have other problems that are interfering with the operation as the trans has been rebuilt by Dodge 3 times. All within 500miles. The TC doesn't want to lock up after it warms up, that's why I tried the mystery switch.



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'96 auto that is going to become a Chevy if it doesn't straighten out

 

[Joe G.]

TPS

Has the TPS been replaced or tested on your truck?

 

[catoiler]

Mine did the same thing the first time i instaled the switch took it to the dealer and had it reflashed cured that problem!now i want to do the force un lock. some ride when it would not stop isin't it!!

 

[SRehberg]

I checked out the TPS per the service manual procedure, and the only thing I found there was the initial voltage was on the low end (. 78V) but tweeking it I was able to get (. 85) It was rock smooth thru the whole sweep and had the 2+volts difference it was required to have at full throttle. So I eliminated that.



It WAS quite a surprise when the TC wouldn't disengage and it started bucking etc. You related you had your truck reflashed by the dealer; any thing I can hang my hat on? My dealer tells me the '96 is "a breed all of its own" with no updates etc. available for it. I don't have a lot of faith in this particular dealer, but I don't have anything that says he is wrong.



Thanks for the input and I guess this problem is not unique.



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'96 auto that is sick

 

[amsoilman]

Are you sure your transmission is not in 3rd gear instead of second when the TCC locks with the mystery switch? The TCC should not be able to lock in second after you are up to speed. Try this to make sure. Put the trans selector in Drive and the Overdrive locked out, then get up to speed and put the mystery switch in the locked position. You should feel the trans shift only two times; ie. from 1st to second, and from second to third. Then when the TCC locks you will feel it lock and by lifting your foot from the accelerator, the tach should not drop off rapidly.



Wayne

 

[Dieselnerd]

If I remember right, the 1996's that were built before March or April 1996 did require a reflash to get the mystery switch to work right. I was told this by Mark Chapple at TST. Of course these days we all know better and are no longer using these switches since they do cause excessive wear on the transmission. The only reason you might want to use one is with an exhaust brake and in that case you should also have a Pressure Loc or some modification that acts in a similar way to keep your TC clutch from slipping with the brake applied. I speak from personal experience and unless you are trying to hasten the demise of your transmission so you can justify some mods, don't use the switch.

 

[SRehberg]

Amsoilman, dieselnerd, thanks for the replies but yes it is definetly in second gear, i. e. shifts one time from a stop and manually engaged the switch. Definite lock up. What's strange, is it won't lockup in the higher gears with the switch, only in second. With it in the normal operation position, starting from a dead stop, it will go up thru the shift sequence normally, including lockup, but don't disengage it (hit the brake etc. ) as it won't lock again. Does o. k. for first 5miles when cold, then after that it's all over. That's why I installed the switch, trying to determine where the problem lies, but it wasn't much help. This isn't for permanant use, just diagnostic for now.



I'm open to all suggestions, as this thing is driving me nuts and the dealer doesn't want to see me again, as the mechanic is eating this on his own time, so I can't vouche for his willingness to do a good job. (4times so far) This all started with a simple lip seal change for the 2nd to 3rd shift problem; just goes to show there can sometimes be no end to the fun one can have when you go to the dealer!



Dieselnerd, the dealer tells me there are no "flashes" for this one, a unique animal in their opinion. Makes you wonder doesn't it. This truck was built Oct. '95.



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'96 2wd with sick auto (37000mi)

 

[catoiler]

Reflash

Their is a reflash for the 96'I will try to get over tomorow to the dealer and get the number and post back tomorow night. did not work before and now it does. ps. the converter is smoked already. thats why I need the unlock. if I give any throttle it starts to slip as long as am crusing it is ok. that fix is next on the list!

 

[SRehberg]

reflash-mystery switch

Catoiler, thanks for the help, as the dealer has basically told me to pack sand. With the number, he will have a hard time convincing anyone to listen to him! Isn't it amazing how much the customer has to teach them?!





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'96 2wd with an auto with maybe some help