Does any one know what this is?

[Ryno]

Sorry if its a horrible pic, its a hard angle to get to...I`m not sure what that white/yellow plastic piece is at the top of the brake pedal above the brake switch.
Long story short, I pulled the MC and Booster from a 99 Grand cherokee to put into my 89 Comanche(automatic trans). But I`m pretty sure I took too much off when I was flattening the part of the rod the brake switch would sit on. It stays loose and this gives me no brake light.  I was thinking I could put a universal brake switch where this white plastic piece is but it is actually plugged up and I do not know what it is.  I couldn`t find it in the Haynes manual and I didn`t know what to call it to search for it in google. Any insight is greatly appreciated. 
 

[Jeep Driver]

Have you got cruise? does it work?

 

If not and you don't care to make it work...................

Universal or Ford brake light switch. The Renix era switches are nothing but a PITA. 

 

[Green Mesa XJ]

Reminds me of a clutch switch for disabling the starter or disengaging cruise control. Maybe it part of the cruise control? Just a early version with a separate switch for the brake light and another for cruise control?


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[Ryno]

I do not have cruze, so that works out.

Oh man that will make it so much easier than trying to mess with that stock brake light switch. Thanks a Million!

 

[Ryno]

Could it possibly a torque converter clutch switch ?

[Green Mesa XJ]

I dunno. On the 91 up XJ the brake switch has a bigger plug and does 3 functions, brake lights, cruise control, siginsl to lock and unlock torque converter.
Not sure about Renix era jeeps. Some google pics look like your switch


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[Ryno]

Stumbled onto this on a XJ forum : https://www.cherokeeforum.com/f2/brake-light-switch-88-xj-206969/index2/

hmmmm, best I can tell that is in fact a torque converter switch....
Bummer, I am still going to have to figure something out for this breaklight switch.

[87MJTIM]

It is the vacuum disconnect for clutch pedal to disengage cruise control 

[Ryno]

If thats the case, I`m in good shape. Because my jeep with the dummy lights most definitely does not have cruze control

[HOrnbrod]

 

23 minutes ago, 87MJTIM said:

It is the vacuum disconnect for clutch pedal to disengage cruise control 

 

Is that switch normally open or normally closed? You need a NO switch for the brake lights. 

[87MJTIM]

I believe it is NC.  When you push in the clutch, the vacuum opens, thus disengaging the CC

[HOrnbrod]

Just now, 87MJTIM said:

I believe it is NC.  When you push in the clutch, the vacuum opens, thus disengaging the CC

 

Yeah, that's what I thought. 

[Ωhm]

Its the Cruise/Trans Switch. Serves two purposes:

1. Vacuum dump for cruise when brake lights are ON.
2. Disengage Torque Converter when brake lights are ON.

[Ryno]

4 minutes ago, Ωhm said:

Its the Cruise/Trans Switch. Serves two purposes:

1. Vacuum dump for cruise when brake lights are ON.
2. Disengage Torque Converter when brake lights are ON.

Thanks, that is good to know. I don`t know that I`d have figured that out by myself

[cruiser54]

11 hours ago, Ryno said:

Could it possibly a torque converter clutch switch ?

Yup, it is.

I converted one of my Jeeps to the single switch from a GM car. bit of a pain.

 

 

[Jeep Driver]

19 minutes ago, cruiser54 said:

Yup, it is.

I converted one of my Jeeps to the single switch from a GM car. bit of a pain.

 

 

A solution to every problem. 

 

I knew you were smart. :)

[Ωhm]

Out of the box and on the bench, doesn't that switch (SL186) have one set of contacts NC and one set of contacts NO? I would think you need both contacts to be NC.

[Jeep Driver]

4 minutes ago, Ωhm said:

Out of the box and on the bench, doesn't that switch (SL186) have one set of contacts NC and one set of contacts NO? I would think you need both contacts to be NC.

You could use one switch, NC, and wire the TC side through a relay, TC side could be NC or NO, wouldn't matter other than how you wire the relay. 

 

Brilliantly simple to do. Explaining so gets one mired in the mud. 

 

Or one could mod the bracket for two switches. 

 

Either way, I don't bother as one of the jesters will dismiss me as usual. 

[Ωhm]

Yes you could use relay logic here or could one just take the output of the correct contacts (connector connected) and feed the output wire (connector not connected) of the other set of contacts. This would a$$ume that all current requirements are meant and that the switch is as I claim.

[cruiser54]

1 hour ago, Ωhm said:

Out of the box and on the bench, doesn't that switch (SL186) have one set of contacts NC and one set of contacts NO? I would think you need both contacts to be NC.

 

Brake switch is NO until brake switch is actuated.

TCU is NC and goes open when brakes applied interrupting power to the torque converter lockup solenoid. 

 

[Ωhm]

Looking at the wiring diagrams (88ELECT, pg20,pg71) both switches close when brake pedal is depressed. How should we address the NC & NO verbiage, when installed on the vehicle or out of the box and on the bench?

[Ryno]

On 8/24/2018 at 9:02 AM, cruiser54 said:

Yup, it is.

I converted one of my Jeeps to the single switch from a GM car. bit of a pain.

 

 

this looks like the most viable option for me.... what did you have to do?
I`m not that bright... especially when it comes to electrical.... was it plug play? or did you have to do some more work?

[Ωhm]

I still think you need a switch, when installed in the vehicle, where both switches (Brake & Cruise/Trans) are closed when the brake pedal is depressed.

[HOrnbrod]

Use an HO 91 or above brake pedal switch and re-purpose it. Each switch has three sets of contacts; two NC (normally closed) and one NO (normally open) set of contacts for brake lights, cruise, and torque converter lock. It mounts the same way as the switch pictured above. It will have to be hardwired in or use an HO brake pedal switch connector w. a pigtail.

[cruiser54]

14 hours ago, Ryno said:

this looks like the most viable option for me.... what did you have to do?
I`m not that bright... especially when it comes to electrical.... was it plug play? or did you have to do some more work?

By the way, your TCC switch is not adjusted properly. Give it a shove till it hits the pedal.