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There is a device, a bulb comparator, hidden in a cutout on the back right side of the passenger tray, at passenger knees. The signals for tail and stoplights pass thru that box on their way to rear of car. Before you go to the trouble of removing the tailcone, you might want to confirm that the power signals are getting to the back of the car thru that box. Usually I find by cleaning fuses, then carefully removing taillight lenses and cleaning sockets, i can solve. Occasionally those bulb comparators fail partially. It is possible to troubleshoot, especially if you take the time to unmount that and take the plug cover off it. A piece of long lamp cord and a voltmeter can also help the process.
On my first car, 84 USA 5 speed, I took off bumper tailcone, which involved rusty problematic fasteners, only to find the problem was in the comparator.
Turn signal lights do not pass thru the comparator. Right and left have own fuses.
Removing tail lenses can be tricky due to interference with tailcone edges, especially if tailcone is cold. Breaking lenses is costly. You can clean the sockets pretty well when lenses are off.
@Landseer , I could not locate the bulb comparator.Do you have any pictures to show me how the bulb comparator looks like and also where is it located?
Thanks Mrmerlin. I believe I was able to locate it. I connected it and the bulb right away turned on. However, still no power from the tail and stoplights. I checked the fused and had good connectivity. So, the next step would be to clean the light bulbs' connections.
I cleaned the light bulbs, the fuses, wire connectIon to frame, connected the Bulb comparator and still no break light on the tail lenses. Only a red light is on and also the side Marker L+R are on when the key is turned on(not on start).
I cleaned the light bulbs, the fuses, wire connectIon to frame, connected the Bulb comparator and still no break light on the tail lenses. Only a red light is on and also the side Marker L+R are on when the key is turned on(not on start).
Any Idea what should be my next step?
Go to the brake master cylinder, there are two connectors plugged in on the underside into the brake light switches. Unplug one and run a jumper between two of the terminals in the socket. I think between black and black/red wire but there are three terminals and in one combination it should illuminate the brake lights if the key is turned on to ignition. If they work, this will tell you that your wiring and bulbs are OK but the brake light switches are bad. If you still have no brake lights you have to troubleshoot the wiring.
I just replaced mine a few weeks ago. The only tool I could get on them was an 8" crescent wrench and they were pretty tight. They did not break loose the way a bolt does. Only a couple drops of brake fluid came out but you have to bleed the system afterwards, my pedal was spongy.
I replaced my switches this way. remover m/cyl cap, cover hole with gladwrap, replace cover - this will stop air getting in and allowing fluid out. Remove electrical connectors. Undo 1 switch at a time (24mm IIRC), screw new one in place, tighten GENTLY. After both are done, remove gladwrap above. Fit the electrical connector (the hard part!). I left mine sit overnight and had a good pedal next day. The switches are cheap Audi/VW parts.
jp 83 Euro S AT 57k
The break switches are really hard to remove. A really tight spot to use the tool. I had the first one out and it is a real pain to screw the new one. Once the first one done I put back the connector and turned on the key. pressed on the breaks. Still no light.
Any suggestion would be welcome. Am I on the right track? ShouldI replace the other switch too? Was hoping it would work with only one replaced.
Also, should I add more break fluid? I lost a lot during the process
10-27-2018, 10:43 AM
