brake light problem

[old_master]

2000 and 2001 are similar, but there are some differences.

The orange wire is in connector "A" pin #4. The white wire from the stop lamp switch is in connector "A" pin #1, which theoretically, pins 2 & 3 should between them. The schematic that shows the stop lamp circuits only shows circuits involved with the stop lights at the multifunction switch so I can't say for certain if there are wires connected to pins 2 & 3.

As far as running a new wire from the stop lamp switch to the multifunction switch: yes, that would work fine. I know the harnesses are packed in pretty tight under there so that would be a satisfactory alternative to locating and repairing the open circuit. When you make your connections, use rosin core solder and heat shrink tubing, do not use crimp connectors. Keep us posted.

[viggy58]

i've been tearing through the wiring diagrams for a while now, and i think i finally have it all understood. the operation of the multi switch, that is. found a new switch for about $90 online, so we're gonna get it just in case, but from what i understand, i'm losing that white wire somewhere between the brake switch and the multi switch. i'm gonna throw a jumper on there next week and see what happens. that is litterally the only thing that i can see that could possibly be causing the exact situation i'm having.

thanks again for the help, and pointing me in the right direction. i'll let ya know how it goes next week.

in other news, it took about an hour to get the hitch bolted up and was really pretty easy. managed to do it myself :-)

[old_master]

Loss of voltage on the white wire at the multifunction switch is the only thing that can cause the problem you described. Give the white wire a once over if/when you replace the multifunction switch. If you look close, you'll find the problem.

[viggy58]

replaced the white wire from the brake switch to the multi switch. voltage is getting to the multi switch and getting lost, so i assume the switch is bad. white wire was also getting voltage at the switch.

so. looks like tomorrow i'll be replacing the multi-fuction switch.

any one ever done this? i know how to get it out of the column, but i'm not entirely sure how to disconnnect the wiring.

[old_master]

In the "How-To" thread for cleaning the contacts in the multifunction switch, it shows how to remove it: http://www.automotiveforums.com/vbul...d.php?t=577320 Might want to try cleaning it before you replace it.... could save you some serious cash!

[viggy58]

yea i've seen that, and used it to take the switch off the column, cleaned it out and everything with no luck. i'm guessing an internal solder joint or something has gone bad.

On a strange note, there is a recall on my 2001 blazer for the hazard switch carrier going bad, causing these exact symptoms (center high mount stop light works, but not the rear brake lights). HOWEVER, i'm working on a 2001 GMC sonoma, and there is no recall, even though the multi switch AND the hazrd switch are the same part numbers.

but more specifically, i was looking for some pics of where/how the harnesses plug in. i have the new one in the box, but last time i took the column off, i dont remember seeing where/how it all plugs in.

i'll take some pics while i do it tomorrow, and add them to that thread.

[viggy58]

woooohoooooooo!

replaced the multifunction switch this morning, and it fixed the problem. I now have brake lights AND turn signals again! I'll add the steps for final removal to of the multifunction switch to the cleaning thread, unless you would prefer i start a new one.

And thanks for all the help! I feel good about the fact that I carried out a full diagnosis/testing before dropping the money on the part.

[old_master]

Good job, glad you got her fixed and thanks for posting back! Add your pics, and anything else pertainiing to the switch, to this thread.

[viggy58]

unfortunatly, i couldn't get any pics, but here's a step-by-step for it. maybe i'll get some pics of the basic stuff from my blazer this weekend. I have to add, i've taken this column apart so many times, it took exactly 2 hours from start to finish to change out the multi-switch.
I also put this in the multi-switch "how to" thread

Here's the final steps to completely removing the multi-function switch, should it need to be replaced:

1. remove everything as described in the earlier steps
2. remove switch from column.
3. there are 2 small connectors on the pass. side of the column. on is green and plugs in towards the ignition switch. the other is black and plugs in near the back of the shifter. unplug these.
4. remove the sleeve from thh wires, cut any cable ties, and reove any tape that is holding the bundle together.
5. unplug the steering column mass connector. if you trace the wires you'll find it, right at the base of the column. A 7mm bolt holds it in. the bolt will back out a good ways, and bring the harnesses with it. a gentle tug will break the whole thing free. note: all of the dash harnesses (4 i believe) are conected together to make this one large harness.
6. the 2 longer harnesses belong to the multi switch. to get them out, look at the bottom of the harness (the side that goes into the mass connector). insert a small screwdriver between harness and the middle piece to push the harness past the retaining notch, then slide down. (do this with both harnesses).
7. remove the multi switch.
8. bolt in the new multi-switch (so it isnt just hanging).
9. install the harnesses into the mass connector thing. seat it, and tighten the 7mm bolt down.
10. install the 2 small harnesses for the ign switch and shifter. be mindful of where you run them, so the don't get pinched.
11. use cable ties, tape, or whatever to secure everything.
12. put everything else back together and test it.