shift indicator lights, and climate control lights coming on when brakes are applied?

whenever i am driving my truck and dont have the headlights on the shift indicator lights and climate control lights come on when i hit the brakes, also the odometer lights dim at the same time.

has anyone noticed this same thing or does anyone have a clue what could be causing this?

 

There's either a problem with the switch, or a short to power, bad ground, maybe a bad ECU. Probably a bad ground; it causes some crazy problems. You'll want an electrical schematic to help pinpoint it.

 

sounds like there are a ton of things it could be

 

can someone explain a little better to me how i can try to pin point what the problem is? its starting to really bug me

 

Before you do anything else, pull the brake/taillight bulbs out and see if one of the two filaments has broken and fallen across the adjacent filament. It has happened to me before.

The symptoms in my case were: no cruise control when the headlights were on, front parking lights came on with the brake lights, headlight reminder beep came on when the door was opened with foot on the brake, probably more weird stuff I can't remember.

Local mechanic wanted to keep it for a couple days so he could track the problem down. Glad we didn't do that, taillight bulbs are much cheaper than a mechanic's time would be.

 

thanks for the response. but i have led taillight bulbs so there are no filaments to mess around with. and i dont remember it starting after i put those bulbs in so it wouldnt seem like that would be the cause of the problem

 

Just read your build thread. Does that deck you have require any wiring to the brake light circuit? Just wondering if something could be wrong with the deck and it might be bleeding power back into the dash lighting.

Pretty rare to have electrical issues with a truck this new. In my experience it has always been a modification gone wrong or something dumb like the bulb thing I mentioned.

Trailer brake converter maybe?

 

the hu just wired into an adapter harness that plugged into the stock one. and a few extra wires added for the ipod and subs. the hu doesnt have an auto dim feature on it where its hooked up to the dash and will auto dim when the lights are turned on.

also there is nothing for a trailer or anything like that.

i was thinking maybe when i did the gauge lights? but all the leds are the same as stock and were soldered into place so i dont understand how that would do anything.

but im also thinking about the running lights, brake lights, and reverse lights are all leds. maybe with the running lights being leds that might have something to do with it? i will have to try and put the stock bulbs in and see if that makes a difference

 

Just a shot in the dark but since the Tacoma has the switches on the negative side of the circuits it sounds like the negative side of the headlight curcuit may be shorting to ground whenever you activate the brake light switch. This would cause the headlights to turn on momentarily and activate the dash light circuits. Look for some kind of crossed wiring between the negative side of the headlights and the wiring between the brake lights to brake light switch.

 

X2 that is it. It's a short on the negative wired somehow. It could be shorted to ground or shorted across circuits.

How to find it? Take the battery posts both off. On the switches figure out which side is the grounded side. Disconnect that side. Check the still connected side to ground for continuity. If you have a circuit there that is were the short is. Somewhere on that run. Check where you moved things around. Could be just a little nick.

 

thanks guys, i will give that a try and see if i can find something. i hope that will be the problem and if it is it wont be to hard of a fix

 

just as an update if anyone cares, i figured out tonight that the led's i had for the tail lights were causing the problem and by putting the stock bulbs back in it fixed it. but thanks to everyone in this thread that offered an idea and tried to help