2005-2014 Mustangs Discussions on the latest S197 model Mustangs from Ford.

Reverse light issue

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Old Feb 15, 2011 | 07:33 PM
  #1  
ejanderson05gt's Avatar
ejanderson05gt
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Default Reverse light issue

I realized the other week that one of my reverse lights was out, so I ordered some LED's from HIDguy.net. They came in today and I went to put them in, and, come to find out, the socket that held the original bad bulb won't work with the LED's or the other working stock bulb. Once I tried to put the LED's in the other socket, they didn't work, either. I put the working stock bulb back in its original socket and it didn't work.

Moral of the story: My reverse lights won't work with LED's or with the stock bulbs, even after trying every combination.

Could a fuse be blown? Is there even a fuse specifically for the Reverse lights, or is it controlled by the SJB? I had the dreaded water leak a few weeks ago, could this be one of the electrical gremlins caused by the leak?
Old Feb 15, 2011 | 08:15 PM
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did you try turning the bulb around and put it in the other way.
there is a polarity on the bulb, it just doesn't say which is + or -.
i just did my dads reverse lights with LED's it didn't work at first, but i turned the bulb 180° and inserted it and it worked.
Old Feb 15, 2011 | 08:23 PM
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Yep, I sure did. I bought some other LED's from them and I had to actually bend the two contacts to the other side of the plastic plug to make them work. I did that with both LED's, as well as turning them around. I literally tried every combination of bulbs/directions/sockets I could imagine.
Old Feb 15, 2011 | 08:37 PM
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Yes, the reversing lamps are controlled by the PCM through the SJB. Sorry to be the messenger of this bit of information. Good luck.
Old Feb 15, 2011 | 08:38 PM
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ok, idk then.
but i dont think they have a separate fuse just for the reverse lights.
Old Feb 15, 2011 | 08:47 PM
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Rater than playing with bulbs to see if things work, use a simply Volt/Ohm Meter and know what is happening.
Old Feb 15, 2011 | 08:54 PM
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Pete, that's on the list of stuff to do at work tomorrow, trust me. Just didn't know if you guys knew of an easier solution. I finally found what I was looking for in the Owner's Manual, and, as I feared, there's no fuse specifically for the backup lights. Looking more and more like a SJB issue.
Old Feb 15, 2011 | 10:01 PM
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BEC Fuse 62(F62), 20amp fuse.

Itīs controlled by the PCM with can-bus signals to the SJB, but not powered by it. Tough to control if it canīt be powered.

Tough to imagine you toasting that though without a short condition present.

Last edited by wayne613; Feb 16, 2011 at 01:58 AM.
Old Feb 16, 2011 | 03:44 PM
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Thanks, Wayne. I'll try my best to decipher that schematic, it's been a year or so since my last circuits class..

I didn't get a chance to check the voltage today, but I'll get to that this weekend and go from there, I guess.
Old Feb 16, 2011 | 05:42 PM
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Nothing to decipher really. Just check Fuse 62 in the engine bay compartment, this is what feeds power to the lights.

If the PCM doesnīt sense the right load it may cut power from that [fuse]/section, was really what I was getting at. Taking a voltmeter reading may not cut it, unless youīre fast, if this is the problem. Iīd put one of the bulbs in and have a friend look at it as your put it in reverse. If the fuse is still good, as is the bulb, itīs quite possible itīs just coming on very briefly, not detecting the right load, then cutting power to it making you think your SJB is fubarian. All the exterior lights are using the low current ĻsmartĻ boards to control if they even try to give power, hence all the issues with hyper-flashing for LED turn-signals, HIDs, etc..
Really, not a big deal to fix, but it can freak you out, and make you think the problem is far worse than it actually is.

Good luck, hope itīs just that fuse.

Iīd still like for an engineer that designs any of these types of setups to explain to me the logic of disabling passing current to a lower threshold load by can-bus switching. If it was returning a diagnostic, that would be fine, but in these cases it just cuts power, and tells you jack-squat. I could see killing power to a sensed increased load, beyond what it was limited for, but less? My WTF-face comes up.

Last edited by wayne613; Feb 16, 2011 at 06:39 PM.



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