2001 9.5 Estate High level rear brake light removal

[peterfrance]

Has anyone info on how to remove the tailgate high level brake light unit please. I have looked inside tailgate but no way to access from there. Unit seems very stuck in position. "Rear Brake light failure" on dash lights up on starting and this unit doesn't come on when I hold brake pedal down. Other rear brake lights work OK.

Thanks

[9-3 Aero]

Did you remove the (upper) glass cover plate? The brake light unit is fixed with three nut, accessed behind the cover.

[peterfrance]

Did you remove the (upper) glass cover plate? The brake light unit is fixed with three nut, accessed behind the cover.

Thanks for info, have removed unit and fuse. Put unit and fuse back and it worked! ok - except for two LED's not working - hence reason for warning "brake light Failure".
Are LED's replaceable item? - If so I can solder them in myself.

[9-3 Aero]

I'm afraid they are not. The least repairable item is the LED strip, P/N 5407572, e.g. 5407572 Genuine SAAB - 3rd Brake Light Diode Strip - Free Shipping.

Of course you could find a "commercial" LED, however not knowing the current surge would be the challenge to compete to avoid the SID warnings. The total watt of the strip is 4, so divide that by the number of LEDs could give you an estimate of the current drawn by the single LEDs.

Maybe it's better to replace the strip for now, and keep the replaced one for piece part spares?

[avid0g]

My LED strip has been intermittantly causing a "Rear Brake Light Failure" warning on the SID for some months. It also winked off or on sometimes. I resoldered the surface mount resistors and leads using a professional soldering station. Since the quick-fix technique didn't work, I reverse engineered the schematic and began measuring voltages.

What finally made this board work was bypassing some plated-through-holes that were discolored. I carefully removed the resin and surface "lacquer", passed a thin wire through each hole, soldered both sides, and trimmed the wires. It works very well now. Total labor: 9 hours. I have time to spare.

I also lengthened two outer holes on the board where screws pass through. This should eliminate strain on the board and lens housing.

My analysis of the board revealed an additional load circuit that works at low voltages and during rapid lamp testing. An open circuit there can cause a SID failure message, even though the LEDs are working. There are two NPN transistors, two 68 ohm resistors and three 4.7 ohm resistors involved, plus some of those plated-through-holes.

The LEDs are arranged first in parallel, then in series, as a four by four array. Here is the primary cause of our center light failures. Paralleled LEDs will have unequal current sharing that causes thermal runaway at high junction temperatures. Any failed LED places great strain on the remaining three, cascading the failure.

I would have designed this as one or more constant current strings. I could almost do it with the existing parts count, but the PCB might require more layers or jumpers. Since cars are exposed to high temperatures, I would prefer to include temperature compensation in the circuit. It is better to have dim lights occasionally, than no lights suddenly.