Brake Light Problem - Need Help

[slowpoke]

Hi,

2003 2500 Quad.

I have one of those intermittent wiring problems that's driving me and others NUTS!. I hope someone here can shed some light or direction.

My brake lights - REAR Fender only not the high mount, come on OCCASIONALY only when the ignition is on. Things will be normal for days then wham start the truck and the brake lights are on.

During this time the highmount light works correctly. Step on the brakes and it works just fine.

Here's the history.

I had a IT remote start/alarm installed and everything was fine for a few days. I used the remote frequently due to the cold weather. Then one day I noticed that my brake lights were on. Shut the truck down brake lights go out. Step on the brakes with the ignition off and the brake lights all work fine.

I have had it back to the alarm shop and one of the techs fooled with it a bit and told me it was the switch out of adjustment. (didn't give me much faith in his abilities because if the switch was out of adjustment brake lights would be on constantly, I think) But the lights worked fine when I left.

I had it scheduled to go in Monday AM to be looked at again, but the phantom problem disappeared.

Now it's back. HELP

My thoughts.

Loose wire or ground somewhere under the dash. (my favorite because there has been a lot of work done under there with wires for the 2 plow controllers and the xm radio being installed as well as the alarm). But where do I look for the wire/ground?

Loose wire or connecter somewhere under the bed.

Bad wiring on the alarm.

Bad alarm module

Note: I have a daniels pull plow with the heavy wiring running down the drivers side rail. I'm not sure if the wiring crosses or crowds any of the original as this was dealer installed.

The alarm installers are starting to point fingers, but none of this started untill the alarm was installed.

I can read and understand wiring diagrams and follow current paths Do you think it's worth my while getting a wiring diagram and just trying to logic it out. Where can I buy a wiring diagram and good repair manual for the truck. I usually get them with most of my older used vehicles but I didn't bother getting any with the new one.

Thanks for any thoughts you may have


~jerry

[Plow Dak]

Hey Jerry
Remote starters have a output that is suppose to go to the park lights to let you know the vehicle is running.. You probably know this.. If they splice into the wrong wire they can cause feedback and such, or they just spliced into the rear harness.. With anything else you have to back track to before the problem. And you nailed it to the starter. I try not to play with the harness in the kickpanels etc. I ran mine out with the safety switch and hooked into the park lamps at the LF fender.. with all the new things in these vehicles it's easy to cause problems.. I would have them look at the hook up's again and get someone else to look at it from that shop. A different pair of eyes might help I don't have a wiring diag to help you. Sorry

[slowpoke]

Thanks Mike,

Good Tips. Strange thing, it went away for a few hours today :headwall Then tonight the dang thing lit up like a christmas tree.

The parking lights work correctly when using the remote and the alarms.

I'm scheduling another appointment with the original installers and if they don't have any luck with it I'll buy the service manual and diagrams ASAP. Local dealer might be able to get it in, but they really don't have a good electrical guy.

I'll keep you posted

~jerry

[Plow Dak]

FYI Jerry
I've had to remove remote starters from vehicles because of gremlins.. (I'm not going to say which ones) Some Manufactures don't want them in there BTW. These had light issues also. In one instance the lights would just flash by themselves for no apparent reason. One went back to the installer 3 or 4 times and finally i had to refuse to work on the vehicle untill it was removed.
This vehicle had a starting problem with the security system and the car just didn't like it. Problem solved with removal.
If they can't fix it and you really want one you could try changing to another brand of starter. That might be an option. I wish you luck

[slowpoke]

Thanks Mike,

I'm going to give them one more try then I'll try to trace back to the source. If it turns out to be the remote starter I'll have them remove it and get my money back. This is the 2nd alarm system installed. the first caused problems because of the interior light delays and other gremlins. They swore that they have never had a problem with this brand, BUT they have never installed one in the new dodge trucks. So time will tell.

Thanks again. I really appreciate your guideance.

~jerry

[wyldman]

Most remote starters have a brake safety feature,so if someone jumps in to steal it,it dies when they hit the brake.

It sounds like that wire from the remote start may be backfeeding current into the brake light circuit.Depending on where they connect it,it may only light the brake lights and not the CHMSL (3rd brake light).

I'd take it back,and have them show you that connection,and temporarily disconnect it.If the problem goes away,then it's the remote start module that's bad.

[slowpoke]

Thanks Chris

[slowpoke]

Hi Guys,

Still need some advise. Fully removed the alarm system and jumpers. It did not solve the problem. Also there is NO indication of any malfunction at the brake switch, no stray current etc.

Then a day or two later the lights went out and work normal. Remember only the brake lights at the back of the truck (not the high mount) come on.

Saturday I took advantage of the good weather and hauled out the power washer and did a real good job of getting the muck out from underneath the truck. I usually just run down to the local car wash and get as much as I can between storms.

Guess what, right after the washing the rear brake lights came on while the truck was running.

Looking back at the weather conditions with the prior problems it appears that they all occurred when the weather was wet or slushy snow with buildups of muck under the truck.

So now the Irish side of the brain comes alive and puts it all together. Something in the rear end is causing a short or a relay in the trailer light setup to screw up.

Can anyone give me some experienced advise on where to look for the suspect connectors or relays?

Thanks guys,


jerry

[wyldman]

I'd start by looking at the trailer plug.It could be full of water or corrosion,shorting the battery charge wire to the brake light circuit.

[slowpoke]

Thanks Chris, I'll check it out tomorrow. I hope that's the problem, but the truck is only 7 months old :(

[slowpoke]

Hey Chris,

I pulled the 7 way apart at the plug. It was clean, but unprotected so I used some non corrosive electrical grease on it and wrapped it up in a baggy for the rest of the season.

It started snowing today *YEA*, when the stuff turned to solid on the ground I went out to fill up the tank. By the time I got back the brake lights were on again.

Is there a connection or relay box somewhere forward of the tail end that would isolate the high mount from the rear end lights?

To my somewhat limited logic it's got to be somewhere after a relay!

Thanks for your help on this mystery.

jerry

[wyldman]

Jerry

As soon as I get a free minute,I'll take a look at the wiring diagrams,and see what I can find.With the impending storm,it may be a day or two. :(

[slowpoke]

Hey Chris,

Don't rush, I've got some nice white stuff falling here now and I'm not going to be able to crawl under the rig for a few days.

Do you know of any supplier of wiring diagrams for the general public?

Thanks

Jerry

[wyldman]

Looking for a copy of the FSM on CD is your best bet.Haynes and Chilton have some wiring in their manuals,but it is lacking.

Try Ebay,I see electronic copies (CD's) of the FSM's all the time.