Turn signals shorting out

nummy · November 9, 2012

I have a 2003 long bed 4X4 Silverado.

I have a short somewhere. If I use the turn signal without using my brakes, the turn signals work just fine.

If I step on my brakes while my turn signal is on. Both turn signal lights on the dashboard will blink along with both turn signal lights and the brake lights will blink in the rear.

I need to get my Sticker soon. Please help

scooby5121 · November 9, 2012

Time to pop off the taillights and inspect each wire.......

Just a start.

nummy · November 9, 2012

Thank - you that is a good idea. I will check it out. The one thing that I did want to mention earlier is that this issue with the short is an occasional problem. So it comes and goes. making it more difficult to nail down.

Doug_Scott · November 10, 2012

You have to look at all the components in the system. At the rear, if the signal and brake light both use the same filament inside the bulb, then the brake light has to be disconnected before it can flash for the signal. I am not familiar enough with the wiring on your vehicle, but, would suspect whatever device controls the power to the brake light filament and turn signal is causing the issue. I don't think a socket can do this simply due to there not being a common wire between the left and right side sockets. The wires at the socket are one for parking light, one for signal, and one for ground. The signal wire is different from side to side, and both wires are powered when brakes are applied, but are different wires. This difference is why I say why it cannot be a socket or wiring issue at the bulb. Note that a socket can cause all the lights to flash, but they would be the parking lights, not the signals flashing.

montyss · November 10, 2012

could be your multi function switch or the lamp board on the back of the taillight

nummy · November 10, 2012

I really appreciate everyone's efforts with this.

Yes, It could be the multi function switch. I found one on eBay.

Is the lamp board on the back of the taillight that you mention,

the junction box that I mention below or is it something else?

I have been out working on this all day. I checked the wiring connections at the junction box in the rear just in front of the rear bumper.

I checked all of the light bulb sockets.

To put this all in a nutshell everything works until I step on the brake peddle and try to use the directional signal, When I step on the peddle all of the lights start blinking very fast. I disconnected all of the cables at the rear junction box to try to isolate the short. Even with everything disconnected the dash lights and the front turn lights blink fast.

So I believe the short is not in the back.

As I am trying to eliminate the easy things. Does anyone think that it could be the headlight switch, the one on the left hand side of the dashboard, that allows me to run the headlights in automatic?

If I turn the switch to manual headlights the turn signal lights dim and stop blinking all together.

By the way wouldn't you know it? The brake light over the cab works fine.

Thanks

Steve

CapitalTruck · November 11, 2012

I had to replace my turn signal relay as it stopped working. This is a sizeable item that is right behind the lower dash panel (knee bolster) on the left. It has like 10 prongs on it. It wouldn't surprise me if this was tied into your problem. Like your issue, I too had it intermittently. Autozone had the part in stock. Ask them for a turnsignal relay and you'll see the size of it.

nummy · November 11, 2012

I just came back from NAPA and tried a new turn signal relay. Thanks for the suggestion but, I had no luck with it.

I pulled out the headlight switch to see if maybe there was a short there, and none was found.

gmtech4 · November 11, 2012

stop throwing parts at your truck,repair by guessing is ...........dumb,be smart and take it to a tech ,if he messes up the diagnoses,its on HIM,not YOU,

how much was the relay?

nummy · November 11, 2012

It was $30.00. I did a lot of research and all points were leading in that direction. So I bought it.

I try to look for the obvious things when I do stuff. This is very frustrating for me because I'm usually very good at trouble shooting. I found a mouse nest under the front fuse box. That was not very nice to see. The mice had lunch with my wires. It's nothing too serious, and nothing that I can't patch up. This whole lighting thing is a mess. I'm going to fix the bare wires that I can find and send it off to the dealer.

The truck lights up like a Tijuana taxi.

Thanks for everyone's help.

Steve

That Nummy thing is just a joke

ujtruck · November 11, 2012

I have a 2003 long bed 4X4 Silverado.

I have a short somewhere. If I use the turn signal without using my brakes, the turn signals work just fine.

If I step on my brakes while my turn signal is on. Both turn signal lights on the dashboard will blink along with both turn signal lights and the brake lights will blink in the rear.

I need to get my Sticker soon. Please help

do you have a 12v circuit tracer ? then use that to find your short

ok - this is how i see your problem, your brake circuit feed hazard light circuit - find and stop feeding volts

tips:

remove trun light flasher and test

remove all turn/park/tail lamps from the connectors, then test

couldn't locate the short, - now you'll need a service manual and some kind of signal tracer or do voltage drop test

CapitalTruck · November 17, 2012

Is this the part you replaced?

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_turn-signal-flasher-bwd_10015245-p?searchTerm=flasher

Having said that, the mouse nest/bare wires are probably not helping things.

nummy · November 17, 2012

I believe that the part in the link above is for a truck with LED lights.

I do not have LED's so I purchased one for non LED lights and was half the price. NAPA, NF LM 455.

http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=NF_LM455_0325413341

I did not get stuck with this part, because I made sure that there wasn't a scratch on it, and the guys at NAPA took the part back.

After all of my research, I found the answer, and I fixed the truck.

There is a ground wire that connects to the frame up under the spare tire. Even though I had this ground wire disconnected, made sure that the contact was clean, and then re connected it. I seams that there was a small break somewhere in this wire. Enough of a break to cause the problem to come and go. I carefully pealed back the black plastic on the ground wire of the harness that comes down from the cab. I soldered a new wire from that point to ground. Sure enough everything worked. It seams that since there was a break in the original ground wire, electricity was finding the quickest way to ground. It was back feeding through the lights, causing them to blink erratically. I don't think that the mice were involved with this. I think it was simple wear and tear. I'm glad that I never got the local dealer involved.

Thanks for everyone's help

All the best

Steve