Need help figuring out how to wire in a "newer" brake light switch

I'm working on my brother-in-laws '90 XJ...and amongst a bunch of upgrades, we decided to swap in a booster from a '96 XJ. I snagged the pedal assembly from the same XJ as the booster, and also grabbed the brake light switch as well.

I've tried searching to find my answer, but haven't found anything incredibly helpful. I'm just needing to figure out how to wire the new switch so it works correctly. There is the 2 wires from the "old" brake light switch ( Pink & blue I think ), and the new switch has I think 6 or 8 wires. Which one is hot and which one is ground?

I haven't dug into it just yet...and I'm sure after awhile I can figure it out, but I wanted to see if any of you guys knew and could save me some troubleshooting? Any help would be much appreciated!!

Thanks!

You don't need the pedal assembly or new brake light switch. You just need the newer booster and a spacer to push it away from the firewall. Junk the pedal assembly and craigslist the switch.

The reason I grabbed the pedal assembly is because the ease of just snapping the post on the side of the pedal into the rod on the booster....save the headache of trying to grind the backside of the post down to work with the old switch. If that makes sense?

I already have everything bolted in place....I just haven't messed with the wiring yet.

Gotlift01 said:

The reason I grabbed the pedal assembly is because the ease of just snapping the post on the side of the pedal into the rod on the booster....save the headache of trying to grind the backside of the post down to work with the old switch. If that makes sense?

I already have everything bolted in place....I just haven't messed with the wiring yet.

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Yeah, but you're trading one headache for another at this point.

if you have a haynes manual or access to one, you can look up the wiring diagrams for the circuit you are working on and kind figure it out from there. I am sure that some of those wires from the new switch would go to cruise or ABS or something similar. you could also hook up a test light to the switch wires and kinda just guess and check until the light comes on to find out which ones to use.

I'm downloading a digital FSM right now....I'll cruise through the wiring schematics and figure out what wires I need. I was going to use the test light to figure it out....I was just curious if anyone else had already done this and could save me a little bit of time.

I'll get 'er figured out, and post back up which wires I use.

Re: Need help figuring out how to wire in a "newer" brake light switch **UPDATE**

Alright...so a little update! That was one of the easiest swaps I've done!

So a little tech:

A Dual Diaphragm booster and master cylinder / pedal assembly from a 1996 Cherokee is a direct swap into a 1990 Cherokee. The push rod to the booster is the same exact length as the original, and with the pedal assembly from the '96, you DO NOT have to mess around with grinding down the push rod for the brake light switch.

The pedal has a stud cast into the side of it that the rod snaps onto....no drilling holes, no bolts, nothing...a simple snap and that is it!

You'll also want to use the newer style brake light switch ( my whole reason for this post ). The pink wire from the "old" brake light switch needs to get spliced into the solid pink wire coming out of the "new" brake light switch ( the pink is the power ). The blue wire from the "old" brake light switch needs to get spliced with the solid white wire. And I'm not sure whether this was needed, but I hooked the black wire from the "new" brake light switch up as a ground. Not sure this was needed, as the brake lights worked without it...but figured it wouldn't hurt.

I'm not sure how to wire it up if you have cruise control, as this Jeep doesn't have it.

So that's it....extremely easy swap, and the brake power is incredible compared to the old one.

The extra wiring is probably for the TCU (unlock torque converter while braking, among other things) and the cruise control. I'm not sure exactly, would have to look at my FSMs.

I'm also doing this swap, using a 96 booster/MC/pedal assembly & switch into my '89, and I was wondering if anyone had any further info on the wiring for the newer style switch. I've searched for some diagrams, but I haven't had any luck so far. I like the switch from the '96, and would prefer to keep that in place of my other two. Any advice with regards to what the other wires are for would be appreciated.
Thanks,
Sean

we just did a 98 booster and master into a 88...used the switch and bolt off the 88 and just swapped brake line form booster up

kastein said:

The extra wiring is probably for the TCU (unlock torque converter while braking, among other things) and the cruise control. I'm not sure exactly, would have to look at my FSMs.

Click to expand...

The switch has 3 sets of internal contacts.

If I remember correctly - from when I pulled the switch apart in my 97/98 to replace a broken terminal ....

One set of contacts is open circuit ... and two are closed circuit ... until the pedal is depressed and they reverse.

Cruise Control seems to be the main function of the extras but as I dont have cruise control I didnt take too much interest ... I was just replacing an internal contact in the switch to get the brake lights working.

PinOut descriptions are in the FSM with wire colours.