My 2001 Suburban 1500, 5.3, 4X4 started giving me fits a couple days ago. Cold snowy night and I was running an errand and the auto headlights failed to come on. No big deal right, this truck has 230K on it and I expect occasional issues. Best I can explain is that now whether the lights are on manually or off, if I am in drive and moving forward my "headlights left on" audible indicator dings continuously and the "brake" light flashes continuously. In reverse, at a stop with my foot on the brake, or idling in park, the ding ceases though the brake light continues to flash. This ding is driving me nutty! I have checked all fuses and replaced one that didn't look good but was not burned.

One thing that may or may not play into this issue is related to my RV trailer connection/wiring. Last summer, intermittantly, when I would hook up my trailer and step on the brake to start the truck the "security" light would come on. The truck and trailer lights all seemed to function but that light would come on before the truck was started. Related or not?? Could towing/trailer wiring be causing this whole issue?

Thanks for any insight!

 

Sounds exactly like a electrical/wiring problem, even a wiring/ground short. If that is the case, and your Suburban flirts between functionality and failure, then I'd get the wiring looked at asap as it could be a fire hazard.

If it was me, I'd pull out a multimeter and first measure output of the alternator to make sure that is up to par. I'd then make sure the battery reads at least 13.75v (pref 14.5v). That stuff is easy, anybody can do it.

I'd then use the multimeter and a couple lightbulb shorts to test all the wiring. If you can't do that, just bring it to a dealer who can do a check.

Always good to pull the engine codes, too, just to have a look. Autozone can let you use theirs for free.

 

Also make sure all grounds you can reach are clean and fresh. Same with positive battery cables. Old grounds can cause all kinds of weird electrical problems. Remove every cable you can reach and clean it up, even the scattered body grounds for various components.

 

Battery and alternator are fine. The obvious grounds look great. Right now it is zero degrees outside and I don't have a heated shop. I was thinking that next I would untape the trailer wiring cluster and see if there is something shorting within that ball of yuk or if the ground there is bad. Also going to unplug the brake controller in case that has failed and is causing something wierd. Now wearing earplugs AND ear muffs and I still hear that dinging. My stereo just isn't loud enough to drown out that ding...