Probably an easy fix, but like it says, my horn and reverse lights just quit working. i ran a quick check through the fuse boxes and didn't notice any burnt ones but thought I might have a wiring issue somewhere. Any suggestions?

Are the horn and reverse lights even on the same set of wiring or are these two different issues I must deal with?

Also, my reverse lock out isn't working, could this all be linked together???

 

Anyone have an idea?

 

The two systems are completely separate. The horn problem is probably a fuse - there's a 20A minifuse for the horn in junction block #1 under the hood (on the left fender).

The backup lights could either be a fuse or a problem with the switch. The fuse is the TURN/BU fuse in the dash fuse panel. Never trust that a fuse is good because it looks good - always use a tester or try another fuse. I expect that the problem is with the switch though, because of your reverse lockout issue. The switch is in the middle of the transmission on the right side. It has two wires - brown and light green. Try shorting the two wires together with the ignition on to see if that makes the backup lights work. If so then the switch is the problem.

 

Is the switch you're referring to the same one that leads to the reverse lockout solenoid?

 

There is no reverse lockout solenoid on an M6 transmision. Reverse lockout is a mechanical function of the shift lever (push down to shift into reverse). Reverse lockout on an A4 transmission is controlled by the brake light switch (lever won't move unless brake pedal is pressed).

The backup light switch on an M6 is a simple on/off two-wire switch in the side of the transmission that allows current to flow from the TURN/BU fuse to the backup lights when the transmission is in reverse. On an automatic this function is controlled by the neutral position switch which is connected to the shift lever.

 

If you don't want to crawl around under the car for testing you could check first at the harness connector under the dash. Look for a natural colored (white) 10-pin connector behind the knee panel under the glove box on the right side of the dash. It will have the following ten colored wires - tan, gray, pink, purple, black with white, orange with black, brown, another orange with black, light green, yellow with black, and dark green with white. The brown wire is the power feed to the backup light switch and the light green is the feed from the switch to the backup lights. Use a tester to confirm that you have power on the brown wire when the ignition is on. If not then replace the fuse or start tracing the wire looking for a break somewhere. Then check the light green wire for power when the ignition is on and the transmission is in reverse. If not then the backup switch or the wires to it are the problem.

 

Great info! I really really appreciate the help!

 

I checked the wires with a continuity testeer with the car in reverse and the power on. The green wire showed nothing and the brown wire made it light up. So, if I understand correctly, I just need to replace the switch and I should be good to go, right???

 

Well, if you tested at the switch then yes, the switch is the problem. If you tested under the dash then either the switch or the wires between where you tested and the switch are the problem. In that case just check that the wires aren't broken someplace before you replace the switch. You might want to check underneath just to make sure that it isn't something as simple as the switch coming unplugged somehow.

 

I jacked it up and checked the plug itself, so it's not the wiring in between. THe plug seemed pretty tight, clean, and the pins looked fine too. I'll order a switch today and see what happens. Thanks for the help!

 

New switch finally got installed, and everything is working just fine.

 

fyi... I had the same two problems on my firehawk turned out i needed to remove the airbag portion of the steering wheel by removing the (2) 25pt hex nuts on the rear. From there I needed to sand down the round nub because it wasn't getting a good ground from that flat piece of metal that contacts it for the horn to work. The reverse light is from the switch on my M6 trans, shorted the two pins on the harness and the lights went on. Thank you for this thread