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sprinkles08, Chrysler/Dodge/Jeep master tech
Category: Dodge
Satisfied Customers: 21410
Experience:  ASE Master and Advanced Certified, Chrysler/Dodge/Jeep Master Certified, Trans and Hybrid Specialist
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Looks like my problem has been addressed several times.

Customer Question

looks like my problem has been addressed several times. wiring an LED flatbed on a 2003 Dodge wiring harness. I have the resistors installed and the brake lights separated from the turn signals as there are four lights, two per side on the back. getting low level feedback when I hook up the brake lights
JA: Have you checked the brake fluid? How's the level and when was it last changed?
Customer: what does that have to do with feedback in the wiring?
JA: What is the model of your '03 Dodge?
Customer: 2500 std. cab 4x4 slt
JA: Are you fixing your 2500 yourself? What have you tried so far?
Customer: I installed a new CM flatbed because the original box rusted off like most Dodges do.
JA: Anything else you want the mechanic to know before I connect you?
Customer: no, don't think he can help
Submitted: 26 days ago.
Category: Dodge
Expert:  sprinkles08 replied 26 days ago.

Hello and welcome to JustAnswer!

If the driver circuits for the lights are properly isolated from each other yet lights are coming on together it's due to a ground issue. The bulbs on the incorrect circuit are lighting because current is flowing through them from the other circuit.

How are the circuits grounded?

How were wiring connections made?

Customer: replied 25 days ago.
I have run a battery ground strap 6 gauge from the truck frame to the flatbed frame. The flatbed has been grounded through hole drilled into the frame which has had the area cleaned off. The connections are soldered and wrapped with shrink tight. Do I have to seperate the brake lights from the turn signals? It has two individual lights on the back of each side and one on the headache rack on each side. Where is the best location to put the resisters? These are LED lights on the flatbed. I have read about horror stories the wiring on these for a dodge.
Customer: replied 25 days ago.
The ground for these is a common white wire like on a trailer. Do I need to split the ground?
Expert:  sprinkles08 replied 25 days ago.

The grounds need to be separate for the turn signal and brake light and they should go to the truck's frame. All connections need to be soldered and sealed with heat shrink, the area where grounding to the frame needs to be cleaned to bare metal.

Customer: replied 25 days ago.
I have to seperate the brake light from the turn signal? It is one combine light but there are three per side. Two at bumper level and one per side on the headache rack. This is typical for dodge but not other manufactures?
Customer: replied 25 days ago.
The first photo shows the park, brake and turn signal combined in each LED. The yellow wire is supposed to be the combination for turn and brake, the brown for parking lights. To be clear, I cannot combine the turn signal and brake lights into the same LED connection? The second photo shows the backup light that shares the ground (white wire) but uses the black wire as a feed for the power. You are saying seperate the turn signal from the brake light, run a ground to frame for all individual lights? Is it ok to let the park brake wire run common to all lights, other than the backup obviously?
Expert:  sprinkles08 replied 25 days ago.

Your earlier posts said that the brake and turn signal lights were separate units. Either way, you can't use one wire to control two functions for these lights. The trailer lights are set up to be controlled by one brake/turn wire but not the truck's lights. They're two separate circuits and have to stay that way.

Why would the black wire be used to power the reverse lights and white for ground?

Customer: replied 25 days ago.
Sorry, I was unclear in my original question. I had already determined I had to seperate them. Yes, they are wired like a trailer with a common wire. Why they use white as ground and black as backup I have no idea. I confirmed this with an Ohm meter and a seperate battery as not to damage the wiring or fuses on the truck. I am in the process of running individual grounds to the lights. As far as the resister to stop the hyper flash for the LED conversion, any suggestions where to put it? I figured at the original splice to the flatbed from the truck would be sufficient. They use yellow for left turn and brake, green for right turn and brake, brown for parking lights, black for backup and white for ground. Trailers use white for ground also.
Expert:  sprinkles08 replied 25 days ago.

A load resistor can go anywhere in the circuit. Just wire it in before the lights.

Customer: replied 25 days ago.
New problem. Truck locked in park. Turn the key off can move linkage manually. Electronically locked. All lights now working except brake lights. They come on dim like parking lights. Wiring harness that is preinstalled for trailers will light the brake light up bright when I tie into it. Although it stays hot after I let up on brake pedal? Any ideas?
Expert:  sprinkles08 replied 25 days ago.

You most likely blew the brake lamp fuse.

Customer: replied 25 days ago.
First thought I had. Checked every fuse in the box under the hood. No luck. Any idea which one it is. Didn't see anything marked truck brakes. 1 is marked trailer battery and electric brake. 15 marked tail and park lamps. 32 right tail lamp. 33 trailer park lamps. 34 left tail lamps. 46 left trailer lamps. 47 right trailer lamps. Anything else?
Expert:  sprinkles08 replied 25 days ago.

Fuse 24 is the one in question.

Customer: replied 25 days ago.
I think we may have it! Sorry to bother you on a Sunday! I am still getting a lamp out signal. I am assuming this is the brake lights that I isolated and need a resistor added to them?
Expert:  sprinkles08 replied 25 days ago.

You'll get a lamp out warning if any circuit doesn't have an incandescent bulb or a load resistor.

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