The power from the brake pedal position switch goes through the driver's under-dash fuse box before it goes to the rear. I included some diagrams in my previous posts and instructed him to check those terminals.

 

1. If you were to splice the wires, it would be best to de-pin those specific wire terminals or cut the wires and splice. Electrical tape by itself may not give very secure and constant connections. Soldering or using splice connectors would be better.

See terminal removal instructions at this link regarding de-pinning: http://www.justanswer.com/uploads/sa...ocedures.pdf//

2. Alternative to splicing would be to replace Connector O and the fuse box. -- I would try to get one from a salvage yard or ebay, etc. due to the high cost of new.

 

The wiring diagram from the shop manual I have doesn't have the wht/blk wire going through the multiplex unit. It looks like supplies power to the highmount brake light, the rear failure sensor, and the multiplex through a common point.

 

Thanks, redbull-1... I think I will go with splicing, and solder it per your guidance. It seems simpler than the replacement job(s).

Here's a question....just to make sure, is there any reason I can't put the "T" I used to back-probe into Connector B #5 and then put battery (+)ve on it to make sure the brake lights light up? That should do it, right? But will I blow up anything else in the fuse box or upstream? If there really is an "open" in there it should be OK, right?

Thanks again!
marks

 

Technically with the open (break) between Connector O and B, it may be okay to test that way. But, if the open somehow closed (intermittently or permanently), adding the power can damage the circuit elsewhere and/or blow the fuse.

You can just unplugged Connector O and add power to the Wht/Blk wire doing downstream to test that the brake lights up.

 

Thanks, red bull-1...that worked. I unplugged connector B, powered cavity 5 and the brake lights lit up! So I am positive about which wire to splice to on that side. On the connector O side, I snip and splice from this one, right? (Circled)

Thanks again!
markb

 

That does appear to be terminal cavity 20 on Connector O; make sure the wire is Wht/Blk on the opposite side of the connector.

Since the Wht/Blk wire at Connector O, terminal no. 20 supplies power to the following, you should not cut the Wht/Blk wire at Connector O.

• ABS Control Unit
• Driver's Multiplex Control Unit
• PCM or ECM
• Cruise Control Unit
• Brake Lights

(See image)

Leave the Wht/Blk wire intact at terminal no. 20 of Connector O. Carefully strip some of the wire insulation away from that wire and splice a new piece of wire into the Wht/Blk wire at terminal no. 20.

Cut the Wht/Blk wire at terminal no. 5 of Connector B and splice the other end of the new piece of wire spliced from Connector O to this cut wire.

 

Done! No proper technician would be proud of my splicing job, but it appears to be working - all three brake lights work! Thanks a bunch, many times over!

I got that done on Saturday (I go real slow, checking each step of the way....). When I took it out for a test drive I discovered it won't idle right - it hunts between about 1000 RPM and 1900 RPM. I looked that up and many sources say that what happens after an older one sits for a while - the idle air control valve locks up. So I took off the throttle bdoy and removed and and gave it what I thought was a good cleaning using carb cleaner and a cheap paint brush. After reassembly it was acting the same. I am investigating that now, and know I might have to buy a new one. But it will be pricey for an old car like this! I'll post a new thread if I can't get it fixed with advice already on the forum.

Thanks again - this is my first time effort working through an electrical issue, and I sure could not have done it without your guidance!

all the best, and have a great Christmas!
markb

 

Good to hear and thanks for reporting back.

Merry Christmas to you too.

 

Hi redbull-1 ... maybe I can tap your know-how one more time. Chasing down the idea surge, I cleaned the IACV, which was in fact stuck, and was able to get the flap to move easily. Or at least, it felt easy. When I got things back together it still had the idle surge... roughly 1100 to 1900 RPM swings. I then did the "idle learn" process that there are several Youtube videos about. Still surging, although now after a couple of minutes it goes into a 200 RPM swing - maybe 1400 to 1600. So based on what I have read, I need to replace the IACV. A number of places say to get a new OEM valve rather than an after market valve. I found that NAPA has one for about half the cost of OEM. My question to you then, is whether you would trust a NAPA part, or would you go with OEM? Getting to it and cleaning it was a breeze compared to the wiring trouble shooting, so I am not scared to the job. I just don't want to waste money trying to save money.

Thanks again!
Mark