Engine/Transmission (1994 - 1998) mystery switch

[Mesenbrink]

Can some one confirm the jumper wire placement for a 98 12V. I removed the relay as stated in TST's instructions and then ran the jumper wire between the two larger connectors. When I turn the key on I get a high pitched noise coming from the passenger side of the engine compartment. Possibly the ECM. What will happen if you ground the circuit and leave the relay in with out the jumper wire? What is the exact purpose of the jumper wire?



Thanks

 

[SBrandon]

It goes in place of the relay located to the imeadiate right of the fuse puller. Or from the right side there are four relays it replaces the relay to the left of the second relay up from the fender. Id post a pic but it appears my camera does not make them small enough.

 

[Mesenbrink]

Thanks for the info SBrandon, I pm'd you with more detail to my question. Out of everybody that has read this no one has any answers? I know there has to be some guys out in TDR land that have installed a mystery switch in a 98 12V. Don't let me down guys.

 

[JustScott]

I think TST's website has a diagram for the mystery switch. I think that is where I saw the diagram when I did mine.

 

[krs]

Mesenbrink,



You did you do the entire procedure? If you did then it sounds like your new switch is closed when you turn the key. It should be open until you're on the road, in drive, and wanting to lock the converter.



The jumper in place of the relay bypasses the pcm control of the torque converter lockup and it will lock, or try, at all times that the key is on unless the circuit to ground is opened by the switch.

 

[wsmalley]

That's not quite true. The PCM will still lock the converter on its own at it's designated times. (3rd w/OD off, or OD) The switch and jumper don't disable the PCM-controlled lockup.

 

[krs]

Oh. I thought that once you cut into the orange/black wire it disabled the PCM unless grounded by the switch. I can't feel it lock unless I do it artificially but maybe that's because of my DTT torque converter. It feels locked almost all the time.

 

[wsmalley]

Well you don't have to cut the wire completely off. All you have to do is splice into it. That way you can still allow the transmission to lock on it's own when it is supposed to. You aren't supposed to completely remove it from the equation

 

[krs]

Youre right. Guess two years is a long time to my memory. I looked at the instruction, finally, and TST clearly says not to cut the wire.



So, back to the problem at hand: Mesenbrink, you energized your switch with the key on but the truck not moving? Maybe your noise is a relay being forced to close when it shouldn't or can't?

 

[RedRamer]

I know I'm late to this party but, I have the same question.

Why does the relay need to be pypassed?



I tried with and without the bypass and get the same results. 3 & 4 lockup.



Now because I also wanted 2nd lockup... with the shifter in "2", I also tried that with and without the pypass on the replay and it won't lock up at all.



If it does the same why not keep the relay in?



thanks

 

[Howard Durand]

There is a purpose for cutting the wire.



Use a three position switch and then you have other options.

You can lock, unlock or leave it up to the PCM.



At some time you may want to be able to unlock the TC even though the PCM, in all of it's wisdom, wants it to remain locked.

I have used it to quickly get out of a high egt situation on a big hill.

Unlocking the TC allows you to stay in gear. Rpm picks up and egt drops and quite often you can scoot on over the hill. The trade off there is a little added transmission temperature but not much.