Strange Electrical Issues After Adding Wiring Harness for Trailer - Please Help!
 

I just finished wiring up a harness for my trailer using the factory wiring on the blazer and a brand new wiring harness. Now that its hooked up I have no brake lights on the truck and a variety of issues. My reverse lights still work and the running lights come on both the truck and trailer but no brake lights at all when pedal is depressed just the running lights stay on. I also lost the little alarm that goes off if you leave the headlights on or key in ignition.

Any ideas? Could it be a fuse? Bad wiring? please advise!

Had issues like that on my camper trailer, there was 3 different grounds on the trailer. Cleaned them up and all set

I checked and redid the ground wires with no luck.I ended up pulling the harness of the truck entirwrly and sti have the issue. I think I either shorted something out or my brake switch could be bad. I can hear it click sti tho. blinkers hazzards running lights and reverse lights still come on but that's it

After a few hours of researching on the forums and various websites I now remember when I first bought my blazer earlier this year there was a piece of metal shoved down as a makeshift hazzard switch in the top of the steering colum, I was able to get it out using a screwdriver and it kept setting off the horn, not sure if this is related or not but wanted to mention it.

THe hazzards do not work, I thought they did but just the blinkers come on, no hazzards with that switch, there is a piece of red plastic down in there, should that be there or is it a remnant of the broken hazzard switch?

For now the truck is undrivable I dont want to risk being rear ended, hope I can figure this out this soon.

it is possible the multi switch is done
the fact that the hazard and horn have issue I would look at replacing it

the brake, hazard and signals all share common wiring so it make sense to me to start there

How do I check if the multi switch is done? The blinkers and horn work fine, it's just a lack of brake lights. The button for the hazzards is gone, there is something wedged down in there keeping it down, not sure what exactly but when I tried to pop it out is when the horn got set off.

So I was messing with the hazzard switch and found if I held the switch half way down it would allow me to use my brake lights again so its just rigged up with a screw holding it in place. Wired the harness back up and everything works again

Good news Glad you got it figured out. Thanks for letting everyone know

The hazard switch could be replaced. I would go straight to the dealer to get a replacement due to the dorman replacements being crappy quality.

You wont find a replacement for a 95 thru 97 years But a 98 + switch will work fine in the earlier years.