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BrakeLights ON CONSTANTLY

2K views 11 replies 4 participants last post by  Warlock III 
#1 ·
Hello Ram world, Ive seen some threads before on this brake light issue, and have followed thru with previous suggestions... however, I have been unable to resolve the issue. I have replaced brake pedal switch, removed my 4-pin trailer connector.. no dice... I am wondering if I am possibly have ecm failure slowly... I have other electrical issues as well... lost my dash illumination to a sudden in dash fizzle.. had to pull fuse. Also when I kill the truck it has a good 3-5 second delay before the motor shuts down. Please help! I love my truck and have put much sweat and toil into it, but am coming up short on this one.
Thanks, Dustin.:4-dontknow:
 
#2 ·
Howdy Dustin. Welcome to the Ram ForumZ. I invite you to stop in at the Newbie Check In section and introduce yourself so other members can give you a proper howdoyado.

I've never hear of a failed ECM, PCM, FCM, BCM, or any type of control module keeping the brake lights illuminated. Sounds like you definitely have some electrical issues, but I'd be willing to bet your paycheck that it's not the ECM failing that's keeping your brake lights illuminated. Have you reset the ECM? I find that resetting it fixes a lot of problems. Disconnect your battery and let it set for a half hour. Turn the key on, then back off, right before you reconnect the battery.
 
#3 · (Edited)
Dustin. The tail lights should be on the same circuit as the dash lights. This is usually done to inform you that the tail lights aren't working. If the dash lights go out then the tail lights and vice verse.

However, you indicate that the brake lights are staying on...

The dash "fizzle" could be the result of a short in the wiring to the tail lights. If the wires going to the rear of the truck have become pinched together and chaffed then there's going to be cross contamination. It stinks, but I believe that you're going to have to trace the wiring above/behind the fuel tank all the way back to the plug-in connector to the tail lights.

I would personally remove the bed. You're located in Texas so I'm a little apprehensive about rust. But It may be a contributing factor.

I'm not entirely sure that it's a brake light issue and may be a short from either the running lights or a ground (positive ground). Since you have removed the fuse that SHOULD rule out cross-contamination in the circuit regarding the dash/tail lights.

I'd start by checking the fuses. Make sure they have the proper size fuse and test the fuses individually. Even though they can look good to the naked eye they still may be bad. There's also a plug about 16-20 inches down from each tail light that could be corroded.

Have you been mudding, submerged, etc?

I'd pull the tail lights and check the sockets to be sure one isn't melted or bad.

I'd check the trailer connector at the back of the truck to be sure that it hasn't become pinched and causing a short in the wiring going to the main harness.

Then if all else failed, I'd remove the bed and inspect the rest of the wiring thoroughly. Especially where it passes behind the tank. If there's some rocks/gravel up there they could have worked their way into the wiring harness and caused a short.

Another alternative is to locate a good harness at a recycler and re-route it to the back of the truck if necessary from just under the cab of the truck.

Isolating the enemy is the first plan at a successful attack.
 
#4 ·
Hey guys, sorry for the extremely long response time. I have ran thru thr process of elimination and found out that it is in fact my ECM module. So now im going to go all out for the infamous 03 to 05 hemi conversion. Thanks to Chris over at Hotwire Auto who specializes in hemi conversions. sending my harness off to him for modification and buying an 05 ECU with 3/4 ton flash (for egr delete). Hope to get this done within the next month or so and give you guys an update. Thanks for all the help.
 
#6 ·
Removing large connector above abs module.

Hello, I have 99% of the harness unplugged and pulled out. only thing holding me back is the large electrical connector above the abs module. I believe it may have a bolt in the center holding it together. its corroded whatever it is. Is that what holds the plug together along with the plastic locks on the side?
 

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#11 ·
I actually had a short in my factory ecm. So with the price of another ecm I decided to upgrade while I was down for repair. the 05 models are a much improved programming upgrade over the first gen 03. And you can reprogram shift points on the trans since the 05 ecm runs the trans instead of using a separate trans control module. also fixes idle issues that were common in 03. Just much better performance, it made a crazy difference. I still need to get my exhaust changed to accommodate the 2 extra oxygen sensors, and will be running high flow cats. But as far as swapping ecm on 4.7 im not quite sure how or if that will change much for it. I used to have an 07 with 4.7 and I could never get it running strong enough for my taste.
 
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