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Brake switch..after 96 booster swap, question about wiring..


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Hey guys, figured someone must have done this by now. I did read the whole post on the MC swap in the projects forum, helped some. But, here is my issue. I want to use the newer switch, what wires do I need to splice. I do have a large white pressure switch on the brake pedal now, not sure what that is? Maybe something to do with the trans selecter (need to brake before you move it)? My MJ is a colum shift. So here is what I need. What wires off the brake switch and this white pressure switch do I need to splice into the 96 pressure switch? I am staying with the 89 pedel assembly since it has the trans selector cable bracket welded on to it. TIA

:cheers:

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ill get a diagram of mine up this week for ya...i used the newer switch with mine...the big white switch is for the cruise control

 

I would really appreciate that diagram, thanks! I don't have cruise control, so I found it odd to have another switch on there besides the brake switch. It was even plugged in.

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The new (1991+) switch actually has three sets of contacts; NO for the brake lights, NC for the speed control servo (cruise), and another NC to the TCU and ECU (cruise also). Switch pin 5 is the 12V input for the brake lights; switch pin 3 is the 12V out to the brake lights. Pins 3 & 5 are the only normally open contacts on the switch, and are all you'll need to wire in for the brake lights. How do you plan on mounting the new switch on the pedal? The bracket is different.

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The new (1991+) switch actually has three sets of contacts; NO for the brake lights, NC for the speed control servo (cruise), and another NC to the TCU and ECU (cruise also). Switch pin 5 is the 12V input for the brake lights; switch pin 3 is the 12V out to the brake lights. Pins 3 & 5 are the only normally open contacts on the switch, and are all you'll need to wire in for the brake lights. How do you plan on mounting the new switch on the pedal? The bracket is different.

 

What colors are the brake wires? I can work with the bracket difference's, easy enough to fix. Just want to figure what wiring to splice into.

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  • 1 year later...

First off, thanks for the info above!

 

Just got finished installing a '95 master/booster combo into my '88...

 

Although I dremeled the rod end of the '95 to match the '88 perfectly, my original brake switch still would not work...

 

So I pulled the whole pedal bracket assembly from the '95 Automatic tranny equipped donor, so that I could use the 91+ brake switch (much better stationary switch design and includes switch bracket)

 

I case anyone else runs into this problem, and doesn't want/can fab a bracket to hold the new switch, I'm happy to report that the '95 bracket swapped over perfectly to my manual tranny equipped '88.

 

You have to remove the pedals from your old bracket, install into donor bracket and drill one small hole into donor bracket to install clutch pedal return spring. reinstall and good to go...

 

FWIW, I needed to use the aluminum spacer from the donor to get the correct pedal height.

 

I had to use a zip tie to hold the switch in place as I stripped its plastic threads removing it from the auto tranny hole in the bracket... New switch is on order

 

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So the pushrod on the booster from the 95 is the same length as the one from your 88?

 

I swapped a 99 booster/MC into the 88 because I needed it back on the road. The rod length is much longer and the pedal is much higher. I'm thinking it will be easier to use a 95 booster than get the pushrods swapped over.

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So the pushrod on the booster from the 95 is the same length as the one from your 88?

 

I swapped a 99 booster/MC into the 88 because I needed it back on the road. The rod length is much longer and the pedal is much higher. I'm thinking it will be easier to use a 95 booster than get the pushrods swapped over.

 

Yes, exact same length when you use the aluminum spacer on the engine bay/firewall side. Be sure to grab it when you get the Booster. Without it, my pedal would have been a bit higher. While your at it take the pedal braket too. (It is somewhat of a PITA to change the bracket as you have to remove the lower dash panel, disconnect clutch pedal and clutch pedal to brake pedal bracket bolt, gauge cluster (to access the two 15 mm top bolts). (EDIT: Just noticed you have an AW4, no need to deal with that hard to reach clutch pedal bracket bolt) Not hard just time consuming.

 

As you found out, the 97+ rod is way too long.

 

You want a non-ABS booster/master from a '95 or '96 XJ (these are the only two years that are mostly plug and play)

 

I got all the brass fittings and brake lines (2, 20" long 3/16 standard thread lines, part no. PA-320) to do the swap from Advance Auto Parts. Hope that helps!

 

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So the pushrod on the booster from the 95 is the same length as the one from your 88?

 

I swapped a 99 booster/MC into the 88 because I needed it back on the road. The rod length is much longer and the pedal is much higher. I'm thinking it will be easier to use a 95 booster than get the pushrods swapped over.

 

Yes, exact same length when you use the aluminum spacer on the engine bay/firewall side. Be sure to grab it when you get the Booster. Without it, my pedal would have been a bit higher. While your at it take the pedal braket too. (It is somewhat of a PITA to change the bracket as you have to remove the lower dash panel, disconnect clutch pedal and clutch pedal to brake pedal bracket bolt, gauge cluster (to access the two 15 mm top bolts). (EDIT: Just noticed you have an AW4, no need to deal with that hard to reach clutch pedal bracket bolt) Not hard just time consuming.

 

As you found out, the 97+ rod is way too long.

 

You want a non-ABS booster/master from a '95 or '96 XJ (these are the only two years that are mostly plug and play)

 

I got all the brass fittings and brake lines (2, 20" long 3/16 standard thread lines, part no. PA-320) to do the swap from Advance Auto Parts. Hope that helps!

 

 

Do you have to swap over the brake pedal assy to keep the pedal from being too high, or can I just install the booster and call it good?

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you may have to swap over the pedal assembly if you don't have the spot for the late model switch if you plan on using it. My pedal sits in the same spot it did b4 the swap...this was very easy and i have had it in my MJ for over a year and a half and love it

 

 

Did you have to splice in the old switch? At the time we did the swap, we had the opportunity to swap over the whole pedal assy but it looked a lot more complicated and time consuming; including updating the wiring.

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