Engine/Transmission (1994 - 1998) 3-Position lock-up switch

[cluckmaster]

Can someone give me an exact shopping list of what I need to buy before starting on a three position lockup switch w/ the amber and red warning lights? Thanks. -Josh

 

[Howard Durand]

I am using a 3 pole, double throw toggle switch with a center off position along with a double pole, double throw relay.

One position of the switch locks up the TC and turns on a red light.

Position two opens the circuit to unlock the TC and turns on a green light. The center off position returns the TC circuit to normal and both lights are out.

There are probably different ways to do this but this scheme works for me and doesn't call for any mysterious electronic logic circuits.

The toggle switch that I am using is a C&K 7303. It is a miniature switch but has a large standard size toggle. I bought mine from Allied electronics but Mouser electronics has them as well.

The relay is a standard 12 volt DPDT relay.



If you would like a diagram of the circuit, I could post it here or send you one.

 

[cluckmaster]

A diagram would be awesome if it's not too much trouble. Thanks for all of the info! -Josh

 

[Eric_B]

I have been wanting to install a 3 position switch or controller . A diagram would be most helpful. Just trying to avoid a possible computer reflash for the switch. I have read allot about early 1996 models (mine 10/95 production) needing a reflash.

 

[Ridesamule]

Eric, you do need the reflash. I did with my 12/95. It was really depressing putting in the switch and going into limp mode/stalling and all the other things that can happen to the early 96.

On the bright side tho I just called my local dealer and told him I would like the TSB towing flash for the early 96. He ran my Vin and at 190K I got the flash, heater wire replacement, throttle linkage replacement. AND the PO had purchased an extended service deal so they changed all my fluids and filters plus the 24 point check. I walked out with a pile of papers a great big smile and never paid a dime.

I did get a lot of questions about not having a TPS tho.

 

[Howard Durand]

I have been trying to get a drawing posted here. It looks OK on preview but becomes unreadable when posted. I'll keep trying.

 

[Graphic man]

I am using a 3 pole, double throw toggle switch with a center off position along with a double pole, double throw relay.

One position of the switch locks up the TC and turns on a red light.

Position two opens the circuit to unlock the TC and turns on a green light. The center off position returns the TC circuit to normal and both lights are out.

There are probably different ways to do this but this scheme works for me and doesn't call for any mysterious electronic logic circuits.

The toggle switch that I am using is a C&K 7303. It is a miniature switch but has a large standard size toggle. I bought mine from Allied electronics but Mouser electronics has them as well.

The relay is a standard 12 volt DPDT relay.



If you would like a diagram of the circuit, I could post it here or send you one.

this may be a silly question... . but why a relay if the TC is locked by using a ground?

 

[Howard Durand]

This is the circuit I am using. I used the relay because, in my opinion, it was the simplest way for me to provide all three configurations of the TC circuit and control the the lights for indication.

There are probably other ways to do it but this works for me.

 

[BILLVO]

If I read this schematic correctly, Did you eliminate the factory relay in power distribution center and tap into a couple of the terminals from it there for your relay? I am a bit confused in that area.



Edit: I just found this link that explains it better.



http://home.pacbell.net/jaybo/image2.gif

 

[EMD-Run8]

There are a couple of transmission websites that tell how it can be setup automatically using a few pressure switches. Do a google search on

47RH, A618 or 47RE. Looks pretty simple.

 

[Howard Durand]

BILLVO, the circuit in the drawing is inserted in the line between PCM and transmission. The relay in the PDC on the later trucks has to be dealt with separately.



The main reason I wanted to use a relay was to allow operation with a simple toggle switch. A multi position rotary switch could be used and eliminate the relay.

Besides, I have a whole shoe box full of small DPDT 12 volt relays that fit in a 16 pin DIP socket.

 

[Joe G.]

BILLVO,



Howard's circuit is on a '94 12 valve. Preventing a CEL is not necessary on a 12 valve. The only way a 12 valve will have a CEL is if the alternator has a problem. If you are not concerned with lights to indicate the status of your lockup control you don't need the relay at all.

 

[TJHenderson]

well this is great, I have been wanting to do this for awhile. But the only worry I have is, when to turn switch on. I know when coming to a stop, to turn it off. When wrenching for gm the 125 trans in early 90, would stay locked up. Can you help with the perrameters. Also by locking convertor in earlier, will this help with fuel economy.

 

[BILLVO]

Raed my post #6 in this thread.



https://www.turbodieselregister.com/forums/showthread.php?t=178608





Can anyone help with this question?

 

[Joe G.]

The circuit in the link above should work fine. The resistor puts a false load on the PCM to prevent it from throwing the CEL. I question the size of the resistor. I'll bet a 1K 1/4 watt would do the job. Nothing in the transmission circuit draws as much current as a 50 ohm resistor. You will need to remove the relay and put a jumper in the socket as shown on the TST web site for the switch to work right. The reason for the three position switch is to have forced lock, PCM control, and forced unlock. Forced unlock is useful if you are pulling and have high EGT with the TCC locked. Forceing it to stay unlocked with raise your RPM so EGT should drop. Trans temp may go up in that situation. If it does then downshift.

 

[Eric_B]

So if I buy an aftermarket lock-up controller will I still need a refash?