Electrical help - brake lights

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SammyAdams

Member
I am new to a 1990 200 TDI.
Driving home yesterday in front of a buddy who informed me that my brake lights were not working.
The lights do turn on when I put on my parking or headlights but not do not get brighter when I put on the brake.
Cursory look at the connections and all looks ok.
The truck came from Italy but through the UK and had passed the UK road safety test before I got it so I assume they were working at that time -
I have no idea when they stopped working or if they were ever working when I got it

When I received it back in Oct, I had to replace the slave cylinder/MC.
While doing this I did break the connection onto the brake booster but recognized it and fixed it though again never actually had someone check to see if the brake lights were coming on
I then drove it to a local rover shop and had them do some work for me - they did replace rear brake cylinders among other things.
It is driving great and now I am frustrated that the brake lights are keeping me from driving it
Could it still be a bulb issue? I have checked fuses and they are ok
Any tips on trouble-shooting this?
Thanks
 
RDavisinVA

RDavisinVA

Technical Excellence Contributor
Jump the 2 wires to the switch and see if the lights come on.
The key needs to be in the run position for the test to work.
 
PJambo

PJambo

Well-known member
It's a bi-filament bulb, so one filament is working (running lights) while your other filament is not. You can test for continuity with a multimeter. I used the 6v battery out of my kid's powerwheels to test both filaments to ensure my bulb was good.

I had the same issue as you, but reverse in that my brake light worked but not the running light. Turned out the wire's connection to the rubber bulb housing had corroded and slipped out. Soldered it back in and I was good to go.
 
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SammyAdams

Member
Sorry I am new to electrical things
To test this do I use a multimeter with the positive on the spade coming out of the hot lead on the top of the reservoir? Do I just ground the negative?
Car doesn't need to be running - just in on key position?
 
javelinadave

javelinadave

Administrator
Staff member
Multimeter set to 12v dc. Red to the spade and black to something metal but not painted and the key set to run. Try both spades because one will be hot and the other not. If you have 12v plug than plug it into the switch. Then touch the red probe to the other switch pole and see if you get 12v while somebody pushes the brake pedal. Let us know what happens and we can go from there.
We will get it fixed for you.
 
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SammyAdams

Member
Thanks for the guidance!
I get voltage from the wire going into the spade
Was not getting voltage out with brake down
Took the cap off and found the reservoir was fairly gunked up
I cleaned it out and reconnected everything
Now I get just under 11 volts coming out of the switch
But still no brake lights
Looked at the bulbs and both filaments are intact

I did just have a bunch of VDO gauges installed boost, EGT, and temp - any likelihood they hit something?
 
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SammyAdams

Member
I guess this means its caused problems in the past? Thank PO!
 

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SammyAdams

Member
Update and back to square 1
I removed the switch - and was finally able to connect the two leads together - still no brake lights
Tested both sides of the switch with vehicle on and brake depressed and there is good voltage at each
I'm starting to think that when my new gauges were installed, something got knocked loose at fuse box?
I'm thinking of undoing the fuse compartment and looking back there - does that sound like the next best step?
 
mgreenspan

mgreenspan

Founding Member
Not a brake light issue.

Front indicator stopped working. Side and rear flash fast like a burnt out bulb. Check bulb. It appears bad. Replace with new. No change. Check voltage in the bulb housing. Appears good. Exact same as the passenger front. Swap that bulb in and put one of the new ones on passenger side. Passenger side still works. Driver side still bunk. Sounds like bad ground? Maybe I'm electrically illiterate but if I tested the voltage using the ground portion of the bulb housing shouldn't the ground be good. I'm going to try a new ground wire in a little bit but if that isn't it then the housing is getting replaced.
 
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