center stop lamp troubles

[dcarrb]

A segment of several bulbs (LEDs, whatever they are) in the "high-mounted stop lamp" on my silver aren't working; enought to activate the STOP LAMP idiot light, which is becoming a bit annoying. I'd hoped to find that these in replaceable modules of some sort, but they're actually soldered into place (all 56 of 'em) on a printed circuit board, below which are several resistors in a row. I'm guessing one of these resistors is bad. Has anyone had any success repairing this unit?

Thanks,
dcb

[Earthworm]

That may not be the cause. Check all 4 of the other brake lights for a poor connection. If you have a replacement bulb handy try swapping each one to see if the dash light stays off.

[TN_fwdsvx]

dcb;

Wiring diagrams I looked at showed a circuit which compares current draw between left and right side brake lamps, but not center lamp at all. I'll recheck the drawings but suspect the center lamp is not causing your stop lamp warning. FWIW, my stop lamp warning comes on sometimes when first starting - due to condensation in one of the lamps. Self-curing after lamps operate a couple of times. I have looked this circuit over a couple of times as I have been thinking of building LED lamps for all of the rear lights and to me it looks like changing one resistor in the warning circuit will keep the warning lamp from staying on after changing to LEDs. I'll recheck it because I was not looking for center lamp and may have missed it.

Replacing burned out LED in center lamp shouldn't be too difficult. Individual LEDs on a circuit board are much easier to replace than almost any other type of manufacture. Resistors are easy to check with even a cheap (<$10) RS meter. Just compare ohms reading across known good and your suspected bad. LEDs are harder to check but not too hard to remove one of your known good LEDs and substitute it temporarily for your suspected bad LED. Most difficult will be locating exact replacement for the LED!

If anyone has specs on LEDs used it would be most helpful to all of us.

Good luck,
Tom

BTW, I bought the Cooper Lifeliner SRTs you recommended. Thanks, good call.

[dcarrb]

All the other bulbs illuminate (I thought they did, anyway) and the bases and sockets of the two I removed were clean and dry, but I'll double-check, have a look at the other two and swap 'em out if I can find some spares in the garage.

Tom, I'm thinking it must be one of the resistors and not the LEDs because those not burning are together in one cluster. The connectors and components in this area were clean and dry, too. If the top-center stop lamp isn't wired into the warning light circuit, I'll probably just leave it be. The gap is only an inch or so.

BTW, after several thousand miles, I'm real happy with the ride and wear of those Coopers.

dcb

[TN_fwdsvx]

If it is a cluster of LED with one limiting resistor - it is probably the resistor. In LED circuits the resistor acts very much like a fuse - current limiter. They can open like a fuse too! Should not be a hard fix.

It may cause the warning lamp also. If the overall current draw in the stop lamps is not high enough, the lamp will illuminate. This is why it comes on with LED stoplamps. Should be able to change the bias resistor in the comparator circuit to correct this - oh, well - a future project. I am suprised that only one cluster of LEDs off will trip the warning - it is a lot more sensitive than I thought it would be.

I comute about 50 miles each way daily in my fwd SVX and the Coopers are doing great. Thanks again for the recommendation.

[ensteele]

You can usually find one of the lights for sale and just replace it. If someone has the info on the LEDs, you could fix it, or try to later on.

[dcarrb]

Originally Posted by ensteele

You can usually find one of the lights for sale and just replace it. If someone has the info on the LEDs, you could fix it, or try to later on.

Yeah, the frugal, DIY angel on one shoulder says, hey, it might just be a 25¢ resistor, so try to fix it, while the lazy devil on the other shoulder says, pfftttt... just buy a used one.

Subaruparts.com doesn't show a replacement for the LED strip alone, which is held in place by just a couple of screws, and the complete "hi mount stoplamp assembly" is a breathtaking $218.22, sans freight.

dcb

[dcarrb]

Update: Y'all were right; swapping out the bulbs did the trick. The LED brake light is NOT wired into the STOP LAMP warning light circuit.

And replacing that LED strip just fell way, way down my list of priorities.

dcb

[mohrds]

See this thread for changing out the LEDs in the CMHSL to newer, faster, brighter ones. It contains part numbers for the LEDs and Resistors.http://www.subaru-svx.net/forum/showthread.php?t=26962