I tried a thread over in C5 Tech several days ago, haven't received
one reply so I thought I would try here.

Quite some time back I did the hazard mod drilling the hole and spraying
the electronic cleaner and got my fast blinking turn signals working again.
My car has been in the garage under a car cover and drove it the first
time that other day in 6 months.

The blinkers started doing the same thing again so I tried exercising the
button and spraying more electrical spray in the drilled hole but it didn't
help. At the same time I noticed I had lost my brake lights, even the
small one. Another strange thing was when I touched my brakes the
interior dash lights and the ones around the radio and hvac would come
on.

I read on here that could all be caused by a bad hazard switch so
I read the thread about the 18 minute trick to replace it. Ordered a
new oem one and replaced, although it did take me longer than 18
minutes. Nothing has changed since the replacement.
What I have done.

Checked fuse #8, looks good but when pulled the dash lights do not
come on when pushing brake.

Pushing hazard switch fronts will flash but nothing in the back.

Pulled codes BO502 BO507 B2482, I think those are from pulling my
running lights fuse.

Bo RFA U1000-H U1064-H

I had cleared all codes then took a short drive and the above is
what showed up. It's going to be several weeks before I can get
into the shop I go to and was hoping I might get some information to
hopefully narrow down where for them (or myself to check).

Thanks in advance for anyone that can help me out.

I also checked for moisture in passenger footwell, it is dry.

 

the C5. Bil Curlee and Lionel Hutz are. How many miles on your car, as that may have a bearing due to the number of switch cycles on it. There are numerous possible causes from dirty grounds, burnt out bulbs, to the multifunction switch to the ignition switch to blinkers. Should be simple. Did anyone put LED bulbs in? They will hyperflash. These guys should be there to help you track it down.

 

On my ride the other day it turned over 50,000 miles. No LED bulbs. The only things I
have done was hardwire my V1 about 10 years ago and also did the headlight mod where
the dims come on with the brights. One burnt out bulb wouldn't cause these issues would
it? I know it was very humid this summer, and with it being in the garage under a cover I
wonder if it could have affected a ground.

I'm hoping Bill Curlee or Lionel Hutz might offer some opinions.

 

just passing through

 

as I am sure these exact sx have been addressed. Yes, these sx can be caused by any of those I listed, I had a filament go in a bulb and keep arcing in the bulb that caused me much grief. The issue you present should be easy to find here. Grounds are particularly fussy,but easily addressed.

 

I've been reading a bunch of threads this evening about the multifunction switch and
sounds like this could possibly be the problem, what is the best way to check the MFS
switch out and do you have to take the knee bolster out?

 

a search of these forums will lead all kinds of guidance. PM Bill Curlee if you need to.

 

I've been doing more reading here, I also noticed today that there are no marker lights,
backup lights and license plate lights. It looks like all of my problems run through
ground g401. Seems one thread I read where someone having similar problems cleaned
this ground and solved his problem. I checked all my rear bulbs today and they are good.
If that's not it than maybe MFS.

Anybody have to clean g401 for light problems?