Engine/Transmission (1994 - 1998) Mystery Switch Instructions

[ndurbin]

I looked around TST's website but I can not find the instructions for the mystery switch with their new website. I found one link by searching but it just took me to the TST home page.



TIA

Nathan

 

[Lnwing]

Nathan,



I used the instructions found on TST's website to install my switch only a couple of months ago, but you're right, it's gone now. I think they want to sell you a controller instead.



I know I had printed a copy when I was working on it. I'll see if it's still in the garage.

 

[CarlJensen]

Pin 54 of the PCM to ground through a switch so the line can be grounded at will. Just solder the wire on after stripping, don't cut it.

 

[Joe G.]

There are two ways to do the switch.



One is to use a single pole single throw with to ground the wire without cutting it. This way allows you to force the TCC to stay locked or let the PCM handle it.



The other way is to use a double throw (center off) single pole switch. With this method you cut the wire. Attach the transmission end of the wire to the center pin of the switch. The ground wire goes to one of the outside pins. The PCM end of the wire goes to the other outside pin. This way allows you to force the TCC to stay locked, let the PCM handled it, or force the TCC to stay unlocked.



I use the second method.

 

[ndurbin]

Joe G.



I am after instructions or something I can see (w/ pictures would be nice) for the double throw switch.



Thanks

Nathan

 

[Joe G.]

I don't really know what to say other than what I said above. I don't have a picture of a switch like that. It's a simple switch that you can get at Radio Shack or a parts store. It has three terminals on the back. If the lever is in the center the switch is off, that is there is no connection between any set of terminals on the switch. If the lever is up the center terminal is connected to the lower one. If the lever is down the center terminal is connected to the upper one. I mounted my switch so that if the lever is up the TCC is locked.



The wire on pin 54 of the PCM is orange with a black tracer. I am assuming that your '94 is wired the same as my '95. It should be since we both have a 47RH transmission.



Find that wire in the cable that goes from the PCM along the top of the firewall. Cut it. Solder a wire to the end of the wire you cut that goes to the transmission. Solder another wire (advise a different color) to the end of the wire that goes to the CPM. Connect a black wire to a ground somewhere. I connected mine to a button on the floor so I can instantly break the ground connected by stepping on the switch. This allows me to unlock a forced locked TCC temporarily for stops or things like that. See a picture of my ground switch in my gallary in Reader's Rigs. The button I used is a dome light switch that is used to turn on the interior lights what the door is opened. If you decide to do it this way get a simple switch. I think mine is from a early '90s Dakota. Connect the wire that goes to the transmission to the center terminal on the switch. Connect the wire that goes to the CPM on the upper terminal. Connect the ground wire to the upper terminal.



The valve body for a 47RH is different for TCC lockup than the 47RE so it behaves a little differently. If you flip the switch up (locked) it will maintain a lockup regardless of anything until the switch is turned to a different position. Note that I said "maintain". It will not force it to lockup like it will for a 47RE. It will lockup IF the hydraulic conditions are correct for that to happen. This means that you will have to give it a little pedal to cause the lockup in many cases. This is important if you are going down hill with a trailer and want to lockup the TCC. You have to accellerate to do that which can get kind of hairy in some cases. It's best to have it locked up before you start down a hill.



I hope this is a little clearer.

 

[biggy238]

How can I get a factory style switch that will install next to the O/D on/off switch on my dash? I checked napa and they said no deal. I'd like to use this switch in conjunction with the two pole-three position switch so I can kick the lock up off for stops by just hitting the switch on the dash.



I also was wondering if the relay has to be removed as per TST's instructions? I tried this setup a few months ago and had no luck with it.

 

[Canadian Cummins]

I am looking to do the 2 position switch mod

But my problem is how do I get the connector or its cover off the PCM?



would it help to remove the air box?

I can see some little tab thingys but they dont want to move

dont want to break the "brains" box I need this as a daily driver!

Help appreciated.

CC

 

[biggy238]

Canadian Cummins- Definately remove the air box. You shouldn't need to unhook the harness from the PCM though.



O. k. this will amuse someone. I rigged up the switch based on Joe G's instructions. All I've got is a cool way to turn on my "Wait to Start" light on the dash.



Whats up with this? I used the Orange wire with the black stripe like TST said. I can get the light on full with the connection that should be the Ground-TCC circuit. Place it the other way and the Light on the dash blips and is gone.



Am I on the wrong wire? I know i've got the papers somewhere. And yes I know the 96 and newer models are different. It shouldd still be the orange/black stripe wire shouldn't it?

 

[biggy238]

O. k. i broke out the manual and the OR-bk is the Wait to start light. So where is the wire I need?

 

[SRehberg]

There's two black/orange wires in the harness, you need to be on B11(?) I believe it is. It's on the middle plug, looking at it, lower left corner of the connector. I own a '96 with the 47RE and it gave me fits trying to get it to work correctly but mine required a PCM reflash. I think the reflash only involved the early '96's but it cured my issues. I installed the single pole, double throw switch as Joe G. suggested and it works great. Going down hill with the exhuast brake and converter locked is a good feeling with a trailer behind you.

 

[Joe G.]

There are two OR-bk wires. I forgot about that. Find the other one. If you look in your service manual you will see the wire on pin 54. If it's not the same as my '95 (I think it is) then find the wire that is on that pin. If you have a 47RE then you have to put a jumper on the relay. The TST instructions had that. With a 47RH like in the '94 and '95 there is no relay involved. The original post in this thread was for a '94 and that is the way I answered the question. If you have a 47RE ('96 and later) and TST does not have the instructions on line any more you will have to ask someone with a 47RE who has installed the switch.

 

[biggy238]

Joe G- I know you were answering that question. I was just in hopes you saw and remembered what I needed to know. I thought they were right together on the site. I found the correct wire. Thanks though. The problem now is that After the first use of the Mystery Switch I lose my PCM control altogether and the truck stops pulling in Drive.

Is it my switch? Mine has an off position (no signal either direction) in the center switch position.



If it's the flash the dealer and I are gonna have a talk because they told me there was no flash for mine. I read the TST instructions and the note about the early 96 models, which mine is. Where do the ends of the jumper plug in of the four slots that the relay plugs into?



SRehberg- is that what your truck was doing pre-flash? If it is, i'll find another dealership to do the flash.



Thanks for the help guys.

 

[Joe G.]

Biggy238,



PM Steve (SRehberg) to get the part number for the reflash. He had to rub their noses in the part number to get the reflash. The dealer may take some convincing.

 

[biggy238]

I would have used my size to my advantage at the time the dealer told me that. It alone is usually convincing enough for alot of people. I was giving them hell anyway because they had trashed my TPS and let on like it was something I did. I let the flash go for that round. But yeah i'll try that. Thanks alot for the info. I put the truck through five or six more runs to see what would happen. It will lock up and hold until it hits overdrive. It shifts and then the TCC unlocks and then I have no forward acceloration because my PCM bails out. I put the jumper in the switched side of the relay ports and It does the same only it doesn't unlock with the switch off. (yeah that got hairy until I hit neutral) Then my PCM bails like before. I kept having to restart to reset the PCM. I wonder how much they'll charge for the flash.

 

[SRehberg]

There is a PM with a note and part number. As I mentioned in the PM, my truck would go into a gear and remain there or it would latch onto lockup without being able to unlock which made stopping interesting. With the reflash, all is well and it works like Joe G. describes in his wiring/switch. I used the switch quite a bit on the last trip I was on without incidence. The dealer who performed the reflash had never heard of what I wanted the truck to do but he was at least willing to pursue it and they found the reflash. Don't give up because the dealer says it doesn't exist... . educate them.

 

[Canadian Cummins]

Installed mistery switch! NO lockup?

I had printed the TST instructions some time ago and followed them for the 96 thru 03's as I have a 1997 47RE.

Found the B11 Orange/Black wire in center connector to PCM, spliced into it and removed the torque converter relay and added the jumper to the pins indicated.



STILL NO LOCKUP, any idea's.



Told the wife not to touch the switch, watch she will flip it and the thing will probably work for her!

CC

 

[SRehberg]

I don't have a lot of suggestions, but it is pretty straight forward. By installing the jumper at the relay slots, it provides a constant 12volts to the solenoid(s). Installing the ground wire, it brings in the solenoid to lockup the converter when ground is supplied, either by the PCM or manually with the switch. Don't take any offense at this, but is the ground good, and the jumper in the right slots? The basics which you have probably have ruled out are most likely. Did you tap into the wire or split it? I see you have a '97 so I wouldn't think yours would fall under the requirement for a reflash like the early '96's. Was the lockup feature working o. k. prior to the tap/splice?

 

[Canadian Cummins]

What Lock-up

SRehberg

Thanks for the tips.

On driving the beast today I figure that the TC has never been locking up, LOL.

Checked the 20A fuse for the circut and I have power to the jumper, this fuse also feeds the fuel pump shut down relay? According to the "Bible"

The ground is good it is inside the cab close to where I grounded the switches for the fog & driving lights, not a heavy load as I have bosh relays for the lights.

I will have to start checking the trans its self! Might have to take it to a shop to get it checked out.

CC

 

[SRehberg]

I hope it is as simple as the connector being loose at the trans, or a wire was broken somewhere etc. If you check to make sure the signals (12Vand ground) are at the trans plug, then in the trans you go. Let us know what you find and good luck.