My car turns its hazards on and off at random and frequently. Sometimes I can press the hazard button to shut them off, sometimes it doesn’t work. I’ve noticed it gets much worse in high temperatures. It happens the whole drive and kills the car overnight.
Here’s what I’ve tried:
Replacing a rear light assembly that had water in it
Replacing the multifunction switch assembly (turn signal and hazard lights) (the issue continues with this unplugged)
I’ve opened the panel to the smart junction box. When I remove connector C2280B, the hazard indicators inside stop, but the four lights outside the car continue the on and off behaviour at random.
When I remove the bigger connector C2280D, the issue completely stops.
I’m confused on what steps to take to track down the issue. Let me know if you need any other information or photos.
Guessing, but seems these are the most likely possibilities
The way it is supposed to work, when the hazard switch is turned on it grounds out a reference voltage from the SJB. when SJB detects ref voltage grounded, SJB sends voltage saying to turn on lamps. There’s a diagnostic code set for a failure in this system, have you checked for that? (DTC B2071) You may have to Google SJB self test procedure, or ask a dealership.
If DTC above is present, is it still present with multifunction switch disconnected? If so is the wire connecting the multifunction switch to SJB to shorted to ground? From what I see the multifunction switch connector C202 pin 1 connects to C2280b pin 48, BN-YE colored wire. You might try just disconnecting and reconnecting those two connecters as a start, might work.
Thanks so much, George. I’ll have to purchase a diagnostic reader.
I don’t think the issue is between the multifunction switch and the SJB, because the hazards (externally) still turn on and off at random when connector C2280B is unplugged.
It only stops with connector C2280D.
Sounding more like a fault w/SJB at this point. You might try disconnecting reconnecting C2280D and Brake position switch C278. try wiggling brake pedal as well, see if it has any effect. No experience w/SJB, but you may not need a diagnostic reader for that, or even if you had a diagnostic reader, it might not work for querying the SJB. Suggest to do more research before deciding if you need a diagnostic reader, or if you do, which one. If you intend to be a diy’er auto-repairer of course you’ll have to have a basic code reader at some point.
Avoid replacing parts on a whim as a way to fix problems. Suggest to get a proper diagnosis from an experienced shop first. They’ll tell you which part they suspect. Then if you want to replace it yourself, have at it. Shop will tell you options where to purchase part.
Another diy’er here with a hard to diagnose engine problem was going down the parts replacement path, eventually took car to shop, who said based on their expertise problem was faulty timing belt. Diy’er then replaced timing belt, problem solved, much time and $$ saved, even after shop fee.