front running lights come on when brake is pushed

[59panhead]

I have had this prob before but it has been ten years or so. I would imagine the hot going to the running lights is wired into the brake light switch instead of the headlight switch. Am i on the right track with this? Both blinkers or running lghts come on when brake is pushed. The blinker lights in the dash light up as well. This is on a 72 cst blazer. Thanks for any help .

[59panhead]

I forgot to mention that the blinkers are not working. I think i should start with the flasher and see whats going on with it. I have a parts blazer so tom i will pull flasher out of it and see what happens. If the flasher is shorted out internally would it make the blinker lights on the dash both come on to inform you that you have a flasher prob?

[panhandler62]

If this is a truck you've had and the problem just appeared then it is not going to be due to wires being connected incorrectly.

[59panhead]

No this is not a truck I have had. Just got it yesterday and I am just getting started working out all the little problems. I have seen alot of trucks and blazers at red lights with both front blinkers lit up and have thought to myself that guys got the same prob I have. I will start with flasher swap out of parts truck and go from there. I just thought that I have seen this numerous times on more than a few trucks driving around so it must be common. With that being said, I really think that this happens when the flasher shorts out or some other part of the blinker circuit is disrupted by a ground. I do agree with you that its prob not wiring. If it was it wouldnt be something I notice on other trucks often while they are at red lights. TIME TO BIRD DOG !!!!

[SamMargritz00]

im with you. i really would like to know whats wrong. my 1 ton started doing it. blinkers dont work, and the clearance lights and turn signal lights brighten with the brake. same symptoms as you. but once night when i was driving it i heard something pop and smelled like a burning smell and pulled over to see what it was. i couldn't see anything wrong but a month later when i drove it again it started doing that.

[59panhead]

thanks for trhe imput sam. yeah there is something that goes out that causes this because my brother called today and said that his 70 nova does the same thing that our trucks are doing. raining in okla today but will start looking as soon as it drys up. prob sat morning. i will let you know what i found.

[SamMargritz00]

The way I kinda see it....I'm glad more than just one person its happening to. At first I was thinking it was a frayed wire from a mouse up in the column of wires. But it sucks that its happening. Lol thanks man for starting this thread
Posted via Mobile Device

[VetteVet]

I think the brake and front turn lights are shorting together in the turn signal switch. Does this happen when either left or right turn is selected?
The front lights are supposed to be isolated from the rear lights when the brakes are applied, but if they are shorted to the brake points in the TS switch then they will come on with the rears as well as the dash turn indicator lights. Another possibility is that the four way flasher switch is shorted to the brake light switch points. If that is the case then all the lights should come on when the brakes are applied even if the TS switch is selected to left or right turn. Either case the problem is in the TS switch.

[fixit-p]

Try pulling out the hazard button and replace the hazard flasher.

[59panhead]

FINALLY FOUND IT!!!!! There are two inline glass fuses that are in the running light wiring assembly. The first in line is located at the windsheild wiper res. on my cst blazer which is on the drivers side up behind the drivers headlight. The fuse is in a rubber housing and is only visible once you pull that rubber apart. The second fuse is located on the pass side at or under the battery box. It also is in a rubber groumet. So the bottom line is this. If the drivers side fuse is bad, the blinkers will not work. I personally think that the blinker lights in the dash light up to inform the driver that this fuse is grounded out and that they will not have blinkers. Not sure if that was there intent, but sounds giood to me. On top of all that , I called my brother with the nova having the same problem and what do you know, the same rubber wrapped fuses are on the nova. So he pulls them apart, bad fuses. Puts new in and waaalaaa.... BLINKERS. So sam, find those rubber wrapped fuses on your one ton and I would be willing to bet you also have a bad" blinker fuse". Hope this helps all you blinkerless chevy owners. Thanks for all the help guys.

[VetteVet]

Those wouldn't be 4 amp fuses would they? I don't know of any fuses inline for the front running lights.

[SamMargritz00]

Thank you so much! I didn't have the slightest idea of checking there. I would've spent hours looking up under the dash. Good job
Posted via Mobile Device

[SamMargritz00]

Time to get the ladder out to get up in there. 6 inch lift with 35's isnt the easiest getting up in there looking around lol
Posted via Mobile Device

[fixit-p]

X 2

Those fuses have absolutely nothing to do with the lights, what you've described sounds like the ammeter fuses, like Vettevet said they are probably 4 amp.

[59panhead]

Well I dont know what to say about them having nothing to do with the lights. I am by no means good with eletrical work but all I can say is that those little 4 amp fuses have fixed the blinkers in two cars in the past day. I have not touched a single other wire on either car and both now have blinkers so it either does have something to do with it or i need to go get a lottery ticket. I guess its poss that i bumped the right wire on the blazer and my brother also on the nova but i feel that is truely unlikely. To add one thing that may help, the nova only did this on the pass side. So he called and said that the drivers side fuse was good. So I said check the pass side. So he called backed and yes the pass fuse was bad. He did not have the little 4 amp so he put a longer 15amp in just to test and waaalaaa. Fixed. I UNDERSTAND what you are saying by looking at the wiring diagram, but I also know that somehow these little fuses fix this prob. thanks again.

[fixit-p]

I'd buy a lottery ticket if I were you. If those fuses have anything to do with the lights it would be because someone totally hacked the original wiring but like you said not likely with 2 different vehicles unless the same person owned them both.
All circuits are fused at the source not the load and the urn signals do not have fuses in these older vehicles because the old thermal flasher acts as a fuse and breaks contact when it heats up.
Here is an underhood diagram of the 2 fuses, they both connect at either end of the charge wire for the ammeter.

[59panhead]

Well the lights are fixed but it may have been just plain old luck. I removed the 4 amp fuses to make the problem come back and it DID NOT. I cant make the blinkers short out again like they where . I dont know if pulling flasher out of fuse box got it a better conn. or like you guys sugg. pulling hazard flasher out and also pulling hazard knob out. Or like you also said maybe the ts switch is going bad and just for the moment it happened to quit shorting. I have touched something somewhere that has made the problem go away. This truck has been under a carport for the past ten yrs or so I can understand the ts switch that has not been moved in yrs causing a short. Maybe me just moving the switch while messing with this problem has helped? Anyway thank you guys for taking the time to help me out. This forum, and the people on it, make dragging these old trucks out of the pasture and getting them back on the road possible. Now im moving on to frozen bleeders in front calipers and u-joints in front driveshaft. Thanks again.

[m455sx]

My parking lights did the same thing on my 62 until i replaced the turn signal switch.

[WIDESIDE72]

Lets bring this thread back from the dead! I bought a 70 Longhorn about five years ago and i am just now getting it roadworthy. I also do not have turn signals, and when i apply the brakes, the front parking lights come on and the turn signal indicators on the dash illuminate. I have a used turn signal switch that I think is food. Im thinking i will unplug the ild one and try the used one to see the results before takingbthe steering wheel off and removing the old one. I also noticed that the hazard switch isnt working.

[VetteVet]

Originally Posted by WIDESIDE72

Lets bring this thread back from the dead! I bought a 70 Longhorn about five years ago and i am just now getting it roadworthy. I also do not have turn signals, and when i apply the brakes, the front parking lights come on and the turn signal indicators on the dash illuminate. I have a used turn signal switch that I think is food. Im thinking i will unplug the ild one and try the used one to see the results before takingbthe steering wheel off and removing the old one. I also noticed that the hazard switch isnt working.

It's always best to start a new thread to avoid any confusion, even though they are similar.

Try jumping the white wire from the brake switch to the yellow and dark green wires in the plug half that goes to the rear lights and see if the problem occurs. Push on the brake pedal and this will light the rear stop lights. If you get the problem then you have eliminated the turn signal switch. It could be a poor ground on one of the lights if it still happens.
I suspect that the problem is in the TS switch.