Handbrake light staying on.

[emperorpatrickiv]

This issue just started recently, where the hand brake warning light on the dash would stay illuminated after releasing the hand brake, and when I accelerated above about 10mph, the aural warning would sound non-stop. I have performed a few tests to attempt to figure out what the issue may be;

1) the hand brake sensor still works: I removed it and tested the switch and wires with a multimeter. They all tested good. In addition, when I press and release the switch I can hear the DRL relay clicking and see the DRLs turning on and off.

2) I have removed and examined all of the fuses and found non of them to be faulty.

3) I have replaced the DRL relay just in case that was the issue, but it did not help.

4) When I turn my headlights on, the problem goes away most of the time, but sometimes it will come on for brief periods.

5) when my headlights are off, the problem persists most of the time, but sometimes the brake light will go away and the aural warning cease for brief periods (measured in the seconds).

6) yes, my brake fluid is full

I am really stumped. If anyone has anything I would really appreciate it. I have done a search and most of the results revolve around brake fluid, but I know the warning for that is different.

 

[Nuje]

You seem to have covered most of the usual suspects.
You didn't mention checking the brake light bulbs (?). I think the bulbs are combination 5/20W tail/brake light bulbs (which might explain why the problem abates when turning on the headlights...current is flowing through the circuit, so warning light goes out(?)).

I'd toss some known good bulbs in there, put some electrical contact cleaner (Deoxit D5 is the cat's meow) on the contacts, and see if it changes any behaviour.

 

[csstevej]

This is just a wag…… is by chance the parking brakes levers fully releasing and allowing the parking handle in the car to make full and firm contact with the switch?

 

[emperorpatrickiv]

@ Nuje - I will try throwing some new bulbs in and see what happens

@ csstevej - I tested the switch by removing it from its mount point and pressing it by hand. I could tell that it was working because the DRL relay was audibly clicking and the DRLs were turning on and off. It performed the same when I reinstalled the switch. No problems with the parking brake switch itself.

 

[csstevej]

No sorry , maybe I didn’t explain it well.
I was talking about if the handle is coming down to make positive contact on the switch, and are the cables completely releasing allowing the handle to come down.

 

[emperorpatrickiv]

@ csstevej - Yes, that is another thing I did check. The hand brake is coming down and completely depressing the switch.

 

[emperorpatrickiv]

Update -
1) I did change out the brake lights and the issue persisted.
2) I got another cluster to see if there was something wrong with mine electronically. The issue did not go away when I swapped them.
3) I did notice that the DRLs are now no longer illuminating, but I can still hear the DRL relay activating when the hand brake button is pressed. I disconnected my headlights and performed a test to see if there was an electrical issue with my headlights, but the issue persisted. All other lights seem to be working correctly.
4) The last few times I drove the car, the brake warning light would not turn off and the beeping persisted no matter what position the light switch was in.

 

[Nuje]

You said in post #1 that you tested the switch with a multimeter, but have you tried activating it with your hand while the ignition is turned on?

 

[Nuje]

Another thread with numerous thoughts / suggestions / fixes:

Help! E-brake light and beep,beep,beep

Started my 01 TDI this morning and my e brake light stayed on. Shortly after a consistent beep-------beep------beep that won't shut off. I checked my brake fluid, coolant, oil, and washer fluid. I don't use my e-brake very often. Anybody know what's goin on? Thanks

forums.tdiclub.com

 

[emperorpatrickiv]

@ Nuje - Yes, I did try activating the switch by hand. I'll look into that thread. TY

 

[Nuje]

...and activating the switch by hand...it worked - or not?

 

[emperorpatrickiv]

@ Nuje - When I activate the handbrake switch by hand, the brake light stays on, but I can hear the relay activate.

 

[csstevej]

Ahhhh the plot thickens……….

 

[Nuje]

Just to try the simple stuff, I'd be one to find a known working switch from another car (the upside of having another Mk4 car here almost all the time) the switch, or even just short the two wires together to see if any behaviour changes.

 

[emperorpatrickiv]

Ok so I was able to figure out what the problem was and fix it. I started by obtaining a wiring diagram for the system, then testing all of the circuits where they interact with the DRL relay since that was a central point in the system. I found that everything seemed to be working correctly. During this, I also found that the instrument cluster requires 12v to the pin for the brake light and aural warning to turn OFF. This led me to perform two tests: 1) a continuity test between a certain pin on the relay and the pin on the green plug that goes to the instrument cluster (according to the schematics there should be one wire with nothing in between), and 2) after disconnecting the relay, testing the same wire for a short to ground. My tests revealed that part of the circuit was indeed continuous, and that it was shorted to ground.

So on the the fun part.

I removed my dash and the tubular support behind it to gain access to the wire conduit, then removed the wire bundle from the conduit. The first thing I noticed was that the wire bundle looked like it was built by a 12 year old. I followed the wire that was supposed to go from the relay to the instrument cluster and found the issue. There are two wires coming from the fuse panel which provide power to the light circuitry; one a larger gauge than the other, both yellow and green. Whomever had made the bundle made the smaller gauge wire about 2 1/2 feet too long and instead of trimming it, they had just looped it back and forth so when flattened the loop was about 5 inches in length. The power draw in this wire over time had caused this wire to overheat and melt. Not only had it melted itself into one lump of plastic, but it has also caused about five other wires to melt to it. In addition, the wire had burned through the insulation where it looped back on itself. This had caused three other wires to burn where they were touching, causing all of them to short. One of these wires was a ground wire and one of these wires was the wire that brought current from the relay to the back of the instrument cluster.

So I removed all of the wires where they were damaged and spliced in new wire at those locations. Everything works now. I was going to take pictures of this, but the section of wire made it into the trash when I was not home.

Hope this helps anyone who may have this issue in the future.

 

[csstevej]

Thanks for the follow up and what you did for the repair.