'91 244 brake light woes

seanj · Post by **seanj** » 14 Jun 2016, 05:19

Lost all my brake lights yesterday driving back home. Made sure the bulbs are ok. Took out fuses 15 & 16, cleaned and put them back. No dice...
I have nothing at brake switch - replaced it and now have 12V over there with brake pressed.

However, I get no voltage at the tail lights whether the brakes are on or off. My indicators/hazards work.

How do I check the bulb failure relay? Hate to throw $60 at a part only to find it ok...

PO did a hack job with the sockets at the tail lights - he soldered the wires into the metal tabs of the lower, outermost sockets (the combination ones that house tail+brake lights - dual filament bulbs) - but irrespective I get nothing when brakes are pressed.

Help will be greatly appreciated.

seanj · Post by **seanj** » 14 Jun 2016, 07:00

Follow up:

the blue-yellow wire is the wire to the bulb-out failure light. cutting it effectively disables the bulb out sensor.

pin 1 - blue-yellow - bulb failure warning light
pin 2 - blue - low beam left
pin 3 NC
pin 4 NC
pin 5 - brown-black, to 3rd brake light
pin 6 - grey, from step relay (low beams)
pin 7 - blue - right low beam
pin 8 - ground for warning light
pin 9 - blue-red - brake light switch
pin 10 - yellow-grey, brake light left
pin 11 - yellow - brake light right
pin 12 - brown-white - tail light right
pin 13 - red - tail light left
pin 14 - grey - from fuse 16 (power for right tail)
pin 15 - white - from fuse 15 (power for left tail)

battery to fuse panel to fuse 7 to green-red wire to brake switch (at brake pedal).
brake switch to blue-red wire to bulb sensor pin 9

bulb sensor pin 5 to brown-black wire to conenctor 'F' pin 15 to brown-black to high level brake light

bulb sensor pin 10 to yellow-grey to connector 'F' pin 19 to left brake light

bulb sensor pin 11 to yellow to connector 'F' pin 20 to right brake light.
connector 'F' is a 2x12 (24 pin total) connector that I think is somewhere near the back of the fuse panel. has a whole PILE of stuff on it

Can someone please educate me on when I take measurements at the aforementioned pins on the bulb failure relay - what is my reference/ground point?

93Regina · Post by **93Regina** » 14 Jun 2016, 11:27

seanj wrote:educate me... brake lights

To light a light bulb requires a positive and negative.

So, one uses a grounded test lamp, and touches the metal-tabs on bulb's receptacle. No go...then pull the wiring harness that attaches to rear-light assembly, and touch the pins on it while brake is depressed, or lights on, etc.

Is there power at this rear wiring harness?

seanj · Post by **seanj** » 14 Jun 2016, 14:36

I figured....but before I get to the tail lamps themselves (those have been rather "tastefully reconfigured' by the PO - so half of it is hard wired and the remaining half uses the PCB - I intend to make it all hard wired in the future), how do I check the bulb failure relay (the red cylinder)?

I have a basic DMM. So positive lead would go to into the pins, but where is a ground point within the dash to connect the negative lead of the DMM?

93Regina · Post by **93Regina** » 14 Jun 2016, 15:23

seanj wrote:ground point within the dash

When I get serious, I run a jumper cable from battery's ground post and use it as the ground.

Late model 1993 diagram...Yours may be different...or the same.

seanj · Post by **seanj** » 14 Jun 2016, 15:45

Thank you! This is what I was looking for..

seanj · Post by **seanj** » 15 Jun 2016, 18:58

So it turned out to be the bulb failure relay...its failed partially. There is no power going to the LHS tail lamp at all.
I am going to try to get a soldering iron and get some jumper wires built to create straight bridge like mentioned on Dave Barton's page.

Might be a few days before I get to it - but I will post back with results.

seanj · Post by **seanj** » 21 Jun 2016, 12:31

She's back! I decided to just get rid of the relay completely. I wired it per Dave Barton's instructions and my lights run great.
The joker who owned this car prior to me wired the lights in such a way that only the outer lights work. The 2 inner tail/running lamps are completely out no matter what. Sigh...

yosef7 · Post by **yosef7** » 03 Apr 2017, 15:04

Can you help me? I am having similar problems. Where are Dave Barton's instructions? Can you send link or copy paste them to me? Thank you. Having shift lock trouble as well. So when the bulb failure relay goes bad things down line go with it. Where is this relay located? Is it also known as the buld failure warning sensor? Thank you [email protected]