Engine/Transmission (1998.5 - 2002) Mystery Switch

[nanpaul]

I Have Recently Installed The Mystery Switch, Per The Information I Received On Tdr. The Only Problem I Have, Is That It Caused The Engine Light To Come On, With The Code P1765. "transmission 12 Volt Supply Relay Control Circuit". On A Receint Search I Read A Post That Stated, Putting A 40 Or 5o Ohm Resistor On The Ground Wire Would Cause The Light To Go Out. I Have Not Been Able To Get Any Further Information, After A Few Emails. Would The Resistor Solve The Problem? If Anyone Has Any Additional Information It Would Be Appreciated. Thanks: Paul

 

[DCreed]

yup thats it. only the Cal. spec trucks seem to have this problem.

 

[JFlagg]

What the heck is a mystery switch? Or is that the mystery..... not knowing.

 

[DCreed]

a manual (usually toggle) switch to lock the auto torque converter

 

[paulb]

Yep, put the resistor in and also put the relay back in, if you pulled it. Mines been working for... oh, about 110K miles. Oh, yeah... . Mines a CA truck too.



Paul

 

[icman95]

Well, I learned something new today. To me the mystery was not knowing what the switch did. Those of us with a stick wouldn't be interested and I've never heard of it before. What a great idea! Thanks for the education guys.

 

[BILLVO]

From what I have read here a mystery switch is a switch that is put in so the rig won't start for security reasons.



The Torque converter lockup swith is just that, I have never read of this being the mystery switch. I have just read all the wrong threads I guess.

 

[Spunkys Ram]

From what I have read here a mystery switch is a switch that is put in so the rig won't start for security reasons.



The Torque converter lockup swith is just that, I have never read of this being the mystery switch. I have just read all the wrong threads I guess.

Maybe that's part of the mystery, not knowing. :-laf

 

[SMoules]

Yep, put the resistor in and also put the relay back in, if you pulled it. Mines been working for... oh, about 110K miles. Oh, yeah... . Mines a CA truck too.



Paul

so you have the the jumper wire and the relay in at the same time? and did you just solder a resistor in line between the ground and switch? as of right now i have the resistor in the ground wire and the engine light has not gone away(i have had the resistor on for more than a week).

 

[paulb]

so you have the the jumper wire and the relay in at the same time? and did you just solder a resistor in line between the ground and switch? as of right now i have the resistor in the ground wire and the engine light has not gone away(i have had the resistor on for more than a week).

No, the relay is still in, but no jumper wire. Yes the resistor is soldered in, between the switch and ground.



Paul

 

[SMoules]

No, the relay is still in, but no jumper wire. Yes the resistor is soldered in, between the switch and ground.



Paul

wow, it does work. :-laf thanks for the info Paul. now if i can only keep the CEL off with the RAD on... ... .

 

[paulb]

wow, it does work. :-laf thanks for the info Paul. now if i can only keep the CEL off with the RAD on... ... .

Glad you got it working. The CEL coming on with the RAD just lets you know it working... :-laf At least it clears after a few restarts.



Paul

 

[nanpaul]

Paul, If I Understand You Comments Correctly. You Said That I May Remove The Jumper Wire, And Reinstall The Relay. And The Switch Will Still Lock-up The T. c. Would It Still Be Necessary To Put A Resistor On The Ground Wire To Cause The Engine Light To Turn Off? Paul

 

[paulb]

Paul, If I Understand You Comments Correctly. You Said That I May Remove The Jumper Wire, And Reinstall The Relay. And The Switch Will Still Lock-up The T. c. Would It Still Be Necessary To Put A Resistor On The Ground Wire To Cause The Engine Light To Turn Off? Paul

Yep, no jumper wire, relay needs to be installed, and you will need the resistor to stop the light from coming on.



Paul

 

[SMoules]

delay?

when i hit the lock up switch, it seems to take about 2 seconds until i can feel the converter trying to lock up. seems to be a delay. is this normal? i guess i was expecting it to try and lock up the moment i hit the switch.

 

[paulb]

when i hit the lock up switch, it seems to take about 2 seconds until i can feel the converter trying to lock up. seems to be a delay. is this normal? i guess i was expecting it to try and lock up the moment i hit the switch.

Some delay is normal. How much depends on a lot of things including TC and valve body. Having some delay is also usually a good thing...



Paul

 

[Eric Lee]

Momentary TC lockup switch

I'm getting a little addicted to the acceleration just after 2-3 shift when the TC finally locks up in 3rd. I don't want to spend another 350 - 450 for a fancy controller so I'm researching the installation of 'the' switch - I am thinking about installing it as a momentary - operated by my left foot. (as a fellow TDR member noted).



I have a Suncoast TC and valve body with real solid shifts at lower rates of acceleration but seems to 'slip' much more at 3/4 to WOT throttle. I'd sure like to put more of that on the ground - but not on the way to the 'input shaft store'.



My question is - how much switching can I get away with? Can I unlock the TC just before gear shifts, lift throttle at speed or when ready, and lock it up after? All for the sake of saving the transmission from a brutal locked up shift.



- Eric

 

[MAleshire]

I don't know if the mystery switch works differently with later model auto transmissions. But, on my '95 all the switch does is establish a ground so the tc can lock up. The tc locks up on it's own sometime after the ground is established. I find that giving a little throttle and then backing off causes the tc to lock up a little more quickly.



Skip

 

[Eric Lee]

TC Stall lockup - 1:1 @ 1800 rpm anyway?

I've been doing a little research today and discovered 'stall speed' and what it is. Here's the article that helped explain it best for me.



How to Select the Right Torque Converter - Car Craft Magazine



The way I interprete all this is that if my Suncoast TC has a stall speed of 1800 rpm (which is what the SC site states) the transmission should reach full fluid coupling at 1:1 somewhere close to 1800. Whether or not the additional lockup clutches are locked up or not.



That little extra 'oompf' after the shift into 3rd has got to be the lockup mechanisms and not the stall speed being reached????? Right?



Anybody on the harshness of the locked up shift?? --- Is it worth the risk for a little speed?



Suncoast's billet input is north of 7 bills. Plus labor.



-Eric