Two birds with one $143 stone

On July 23, 2010, in Automotive, Personal, by Rob Levandowski

A few months ago, I finally got around to sending my Saab 9-5’s Information Display off to be repaired.  (That story would make a good blog post itself…)  Soon after it came back, now with 100% working pixels, my Saab wanted to test it out.  It did so by telling me: BRAKE LIGHT FAILURE.

Okay, no big deal; you can replace the brake light on a SportWagon with the provided screwdriver and about three minutes’ time.  (The only trick is realizing that you have to sort of rip the thing back and to the side after undoing the two screws, as the front edge of the light assembly is held in place by two friction-fit pop-in pins.)

I have my girlfriend Kim go around back while I step on the brake, so we can identify which light has failed.

They’re all working.

So this happens sometimes; you get a bulb with a loose filament that gets intermittent.  I push CLEAR on the SID.  A day or two later: BRAKE LIGHT FAILURE.

But they still all work.

This goes on for a few weeks, before I remember to go searching the Internet for the answer.

The first recommendation: Sometimes the sensor gets confused if the impedance of the bulbs on either side of the car becomes different.  That could happen if the bulbs are from different manufacturers, or if the contacts in the bulb socket on one side have gotten corroded.

I replace both bulbs from a new package. While I’m at it, I clean the sockets with a pencil eraser, even though they look reasonably clean.  I also don’t see any broken wires.


Well, according to the Internet, that left one thing: the center high-mounted brake light. It’s an LED strip on the SportWagon.  Apparently, sometimes the circuitry flakes out and it ceases to identify itself as “good” to the sensors even though it works just fine.  (I wonder if it’s yet another component sourced from Lucas Electric, the Prince of Darkness.)

Being LEDs, the CHMBL is expensive: $142.99 at, my preferred vendor of Saab bits.  But I’m tired of BRAKE LIGHT FAILURE, so I pony up.

There’s another problem that this may help, as well.  For some time, I’ve had water leaking in through the back hatch, making wet spots on the cargo cover. It seems that this can also be caused by the CHMBL.  Sometimes the foam seal around the edge goes. Sometimes the lens cracks. Sometimes the plastic ears on the back that hold the bolts in place crack and it loosens from the car.

Soon thereafter, the replacement CHMBL arrives.

Among the things I adore about my Saab is that the engineers clearly considered routine maintenance when they built it.  The parts you might have to replace are generally easy to get to.  In this case, the trim panel at the top of the back hatch pries off easily, and there’s the three nuts that hold the light in place.  Disconnect, loosen, remove, insert, tighten, connect, and pop the cover in place… no sweat.  The hardest part was finding where I’d left my metric socket set; it’s one of the few lighting repairs that can’t be made using the tools provided with the car.

(I really love that Saab, unlike other GM vehicles, uses stout metal push-clips for trim pieces that are designed for repeated use without loosening or breaking.  American carmakers have always loved those plastic once-if-you’re-lucky trim panel clips that usually need to be replaced every time you remove a panel…)

The original CHMBL did indeed have a cracked lens, and the plastic ears for the center bolt were loose as well.  My theory is that water got in through the crack and/or seal when it poured, and possibly damaged the circuitry, as well as causing the damp spots.

A few soaking rain storms later, I have no damp spots in the cargo area, and no more BRAKE LIGHT FAILURE on the SID.

Hopefully this post helps a few other people who run into a similar pattern with their Saab.

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