DSC and no Speedo

Xman13 · #1 06-07-2013, 12:06 AM

Ive read a bunch of posts on the DSC, ABS, and speedo all connected. So I changed the speed sensor on rear drivers side wheel. Still have all three problems. Does anyone have other ideas? Also the A/C quit and the 3rd brake light and drivers side brake light are always on. The drivers side does not work. I have read that these are related. Anyone?

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TerminatorX5 · #2 06-07-2013, 01:15 AM

LCM will activate emergency lighting if one of the main lights is defective... check all the lights in the rear to see which one is acting up - it could be a corrosive contact, intermittent issue (if the issue presents itself several times in one ignition session, the LCM will stop sending voltage to the offending circuit and activate the bypass)... same applies to the headlights - if the one headlight is out, the fog lights come on automatically, to ensure safe passage...

you replaced the speed sensor - was it bad in the first place? how did you test the bad sensor? did you test the sensor at the plug at the ABS module? i've had an issue with a sensor, not reporting to the plug, when i pulled the sensor from the wheel, the sensor was good... real head scratcher... but.. it was the line, between the sensor and the module - there was a chaffed wire... so, in my case, removing old good sensor and replacing it with a new good sensor would not have yielded any results - the sensor was still good but the line was bad...

also, there was a member, who replaced a sensor with an aftermarket sensor and still had issues, as the voltage read just the half of the value that was present on the other 3 sensors... so, he got himself an OE sensor and the problem went away...

just giving you food for thought...

Xman13 · #3 06-07-2013, 09:13 AM

Yeah I bought a cheapie off Ebay. Guess Ill have to get out my meter.

Ricky Bobby · #4 06-07-2013, 09:29 AM

cheapie off ebay is most likely the culprit, aftermarket sensors are pretty much a no no since they are so sensitive.

I know the speedometer is related to one of the rear wheel sensors, are you sure its the rear left? You probably should have gotten the car scanned to see what DSC codes you are throwing too, as the "yellow trifecta" of lights could also be related to an ABS module throwing random errors and needing repairs.

Xman13 · #5 06-07-2013, 09:36 AM

When you say scanned, are you referring to a BMW specific scanner? I bought a OBDII scanner to pull engine codes but I dont think it will pull other codes. If so where can I get one or is this a BMW repair shop only item?

Ricky Bobby · #6 06-07-2013, 09:44 AM

BMW specific software to scan the DSC module, we refer to it here as GT1, but also any independent shop who has an Autologic tool should be able to scan the module to find the errors reported.

That's not to say that your sensor may be the culprit, but with just generically buying an OBDII scanner you're just throwing parts at a problem with a guess, generic OBDII scanners don't really do too much good for our cars, each module throws its own specific codes.

Xman13 · #7 06-07-2013, 10:41 AM

I understand and thank you for the info. I had a check engine light come on and needed to know what it was right away. I just bought it and was thinking the worst.

Big "J" · #8 06-07-2013, 10:42 AM

I had the trifecta issue almost for 2 months and in the end it was a bad alternator. Stereo and a/c would cut off for about 30 seconds and after clearing the error codes, a short drive later the 3 lights were back on again.
Make sure you're getting a good charge from your battery and alternator.

Good luck!

Xman13 · #9 06-07-2013, 11:09 AM

OK. I would just replace the alternator if it was a direct swap. I have heard that i should rebuild the one I have so the pulley will fit. The new ones dont come with a pulley? I have 110K so its time to replace anyway.

Ricky Bobby · #10 06-07-2013, 11:25 AM

You should probably be sure if the alternator is bad first before replacing lol.

Unlock your OBC first, run test 9? I believe is the voltage test. If you are staying between 13-14v while running you are ok, if you are dipping under, or over, you may need a new alternator.

Search Slick GT1, his signature has the link for the unlocking procedure to run the tests. And update your signature so we know the year of your X, any relevant options and engine type information, would be much more helpful for anyone who is trying to help you out.

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