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2003 Dodge Ram 1500 Brake Lights Stay On

Tiny
WALLACE7777
  • MEMBER
  • 2003 DODGE RAM
  • V8
  • 2WD
  • AUTOMATIC
  • 138,000 MILES
On my 2003 Dodge Ram 1500 W/5.7L, brake lights stay on when ignition is switched to run without the brakes applied and my cruise control does not work. When the ignition is turned off, the brake lights work as they are supposed to. The third brake light works as it is supposed to all the time no matter the switch position. This will happen for a day or two then everything will go back to working for a day or two like it is supposed to then it will mess up again. I replaced the brake switch thinking that may fix it and saw no difference. I have the “Complete” service manual for my truck and noticed there are three circuits in the brake switch and tested the #4 contact on the brake switch and found no power supply on that wire, I have found this is the Speed Control Supply/Brake Switch No. 2 Signal. It is circuit V32 in the brake switch Pin# 4 “V32 20YL/RD SPEED CONTROL SUPPLY/V32 20YL/RD (5.7L) BRAKE SWITCH NO. 2 SIGNAL”. The lights started working again for a day and I probed the #4 wire and had power, plugged the connector back into the brake switch and “Boom’ no power and brakes came back on with the ignition switch on and the cruise stopped working again. I have jiggled wires around and don’t think I have a short or open... Where can I check next to trace the problem back? I am thinking this problem is the PCM but I would like confirmation. If it is the PCM, does this have to go to the dealership to be programmed after install or can I just plug it in and go?

Thanks,

Eric
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Wednesday, March 30th, 2011 AT 7:26 PM

11 Replies

Tiny
CUP1981
  • MEMBER
  • 133 POSTS
Hey Eric,

What I am seeing en my schematic is that the brake light switch wires directly into the CHMSL, which is why it still functions just fine. The fault is in one of two places: the instrument cluster, or the PCM. The brake lights run through both of them. The only component that both the brake switch and the cruise control run through is the PCM. By reasonable deduction, I would say it is the PCM. Have the PCM checked by a specialist, they should be able to tell immediately if the PCM has failed or not.
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Monday, March 8th, 2021 AT 12:21 PM
Tiny
WALLACE7777
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The CHMSL is understood, that is why I was clear that the CHMSL was working correctly. However, the Tail Stop Lights work correctly as well with the iginition off. When the iginition is turned to run is when the stop lights come on and stay on. Does this supply circuit go through the instrument cluster after the brake switch or before? I don't have power to the YL/RD wire #4 at the brake switch and would like to be able to trace it back to the defective source (likely the PCM) before I take it to the dealer and waste money due to a possible break in the wire prior to the connection at the switch.
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Monday, March 8th, 2021 AT 12:21 PM
Tiny
CUP1981
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  • 133 POSTS
Sorry it took me so long to get back to you. This Schematic runs all different directions. What ever happened to power + ground = light :). Anyways. The yellow/red wire that runs from the #4 pin on the brake light switch (Speed Control Supply/brake switch no.2 signal) receives its power from the PCM. Probe pin 14 on the PCM with the ignition off and then on and let me know if there is power coming from there. If not, it's the PCM, if so, I will need to dig farther.
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Monday, March 8th, 2021 AT 12:21 PM
Tiny
WALLACE7777
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Ok, I had to go out of the country and decided to leave the truck with the dealer. Was contacted and told the TIPM is the problem and claimed they had called Dodge to confirm. $900.00 later I pick the truck up yesterday and brakes are working fine. Go out this morning to head into the office and decided just to take and peak. Brake lights are on again.
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Monday, March 8th, 2021 AT 12:21 PM
Tiny
CUP1981
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Ok, it sounds like the dealer went the "obvious" route instead of taking the time to really pinpoint test this thing. Try probing the pins I mentioned on March 31 and let me know the result.
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Monday, March 8th, 2021 AT 12:21 PM
Tiny
WALLACE7777
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The truck was back at the dealer during the time I posted my last response. They swapped out a PCM from another truck with the same options as mine and had the same problem. When they put my PCM back in the PCM wanted to be reprogramed, after doing so the problem immediately went away. I went and picked it up after they used my truck as a taxi for three days and burned 1/4 tank out trying to get it to fail. They couldn't get it to fail. I drove about 10 miles away to go have dinner with the family, parked the truck to go in and decided to turn the ignition switch back on and check. Brake lights back on. Took it back to the dealer and received a call an hourt later rambling about how the brake switch does this and brake switch does that, he put a new brake switch in and he says it is fixed. The problem is, I pulled the old switch out and ohmed it and it seemed to be fine. I replaced it anyway, the dealership pulled one from another vehicle just to check and now he has replaced it again with a switch that he says Dodge has revised and the old switch must have a problem. 4 brake switches later and they think they have fixed it? I am very suspect about their hypothesis and also the professionalism and training of the staff at this dealer. The problem is, after the problems Chrysler had a few years ago and all the dealer closures, this is my local dealer option. I really don;t think they fixed my problem and am probably going to go pick it up only to send it right back.
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Monday, March 8th, 2021 AT 12:21 PM
Tiny
CUP1981
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There is a slim possibility that Dodge has updated this part, but I see no record of it anywhere. I would give them a chance to make this right. Keep in mind, at this point you should't have to pay them anything more for labor than you already have. Parts you still ned to pay for, but the labor should be free. Let me know how it comes out.
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Monday, March 8th, 2021 AT 12:21 PM
Tiny
WALLACE7777
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Ok, the switch and tipm isn't the problem. It would mess up only after about 10 min of driving. Had Cartoys come out and remove the remote start system and alarm(they also disconnected the aftermarket steering wheel controls I had installed a couple of months ago. The brakes aren't messing up now. Not to say they won't but they usually mess up in about 10 minutes of driving and cycling the key, 2 days later and 120 miles. Working right so far. I was wondering, they had spliced into the grey white/stripe wire for the stereo controls(radio control MUX wire) and it goes to the clockspring and cruise circuit, remember I didn't have cruise either. Wondering if alarm/remote start/radio contols where causing this?
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Monday, March 8th, 2021 AT 12:21 PM
Tiny
CUP1981
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That would be the likely culprit. The brake lights actually go through the speed control (AKA Cruise control) system at one point. This truck really overdid the brake light technology. Adding the remote start, if not properly adapted, could absolutely create this problem.
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Monday, March 8th, 2021 AT 12:21 PM
Tiny
RC51GUY
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I had the same experiance on a friends 04 1500, he's a 25 year honda/acura. Before reading this post "and others" we had done almost the same troubleshooting, we swapped out the ecu, the the cluster, and bought a brand new power distrupution center with this problem still occureing, same exact symptoms. And when looking on the web it seems the problem is all the same with whoever has it. Well, he replaced the switch and yes it did the same thing. But there is a proceedure for setting the switch, there is a small lever on the switch that has to do with setting the switch. After buying the switch and properly going through the prooceedure the lights are working fine.
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Monday, March 8th, 2021 AT 12:21 PM
Tiny
M.A.D
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I have an 2003 dodge ram 1500 thunder road laramie. My brake light is stay on with the truck running or ignition switch is on and since my brake light stay on. My cruise doesn't work also. But the 3rd light above the window work fine. As soon, I turn the truck off. Brake light work fine. Have already replace the brake light switch, order two tail light module from the dealer ship. Also so swap out the FCM and still having this problem. Been to the dealer ship, they slap on a brake light switch & till me to take out the after market tail light & make the ordinary tail light back in. Did all that & till having problem.
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Monday, March 8th, 2021 AT 12:21 PM

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