Today: What's a CHMSL and How Do We Fix It?

Dear Car Talk

Dear Car Talk | Sep 04, 2014

Dear Tom and Ray:

I need to remove the upper light cover on the back hatch of my 2012 Subaru Outback, Limited, 6 cylinder. My book has instructions on how to change the bulbs, after removing the covers on all the car's exterior lights -- except this one. The light is almost at the roof line on the back hatch and has no inside or outside screws, and I am reluctant to try to pry it off, unless that is the only way to remove it. Is that how it's done?

-- Brenda

TOM: Well, that is the tried-and-true method, Brenda. But I wouldn't try it in this case.

RAY: You're talking about your center, high-mounted brake light, for which there's a horrible acronym.

TOM: They call it the CHMSL, pronounced "chim-zel," which stands for Center High-Mount Stop Light.

RAY: That might not be the worst acronym ever, but it deserves a nomination, along with: PUMCODOXPURSACOMLOPOLAR, which stands for: Pulse Modulated Coherent Doppler-Effect X-Band Pulse-Repetition Synthetic-Array Pulse Compression Side Lobe Planar Array.

TOM: And my personal favorite: CINCUS, which, for many years stood for Commander in Chief of the U.S. Fleet, until someone realized is was pronounced "Sink us."

RAY: Anyway, most CHMSLs these days are LED fixtures (that's Light Emitting Diode, by the way). So when they stop working, you have to replace the whole fixture. And, depending on the fixture, that'll cost you somewhere between $75 and $275.

TOM: So, if I were you, I'd high-mount my nearest brake light, and gallop over to your nearest Subaru dealer. On a 2012 car, I think you can reasonably ask them to replace it under warranty.

RAY: I don't know exactly what the lifespan of this third brake light is ("TBL" is what I would have called it). But since it's an LED, and I'm a demanding SOB, I would expect mine to be my BFF and last the life of my vehicle. Or pretty darned close.

TOM: It's also possible that there's a wiring problem rather than a bulb problem. But in either case, I think a warranty claim is called for, Brenda.

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