ABS/Brake Light Loose Connection

Both the ABS and emergency brake function perfectly. But when the weather is cold, i.e. mid 50's and below, the ABS and Brake lights on the dash will chime and turn on when I drive over bumpy roads. It doesn't happen all the time, and not on every bumpy road. If the temperature is warmer the lights never come on. When I start the truck they are the last to lights to turn off. There are no codes related to either system.

My thinking is that there is a loose connection that is exacerbated when the temperature is low enough to contract the metal in the connector. I'm also thinking that the loose connection is probably near one of the rear wheels where the ABS and emergency brake wires come together in a harness or connector. But at the same time, I'm not discounting the possibility that the loose connection is behind the dashboard. Am I on the right track here, or is there a more likely culprit? If it is more likely to be near one (or both) of the rear wheels, where should I look to find the connection?

Thanks.

 

Both are Timken, and have been replaced in the last 5 years. I do a lot of long distance driving, and try to pay close attention to the bearings in the way they feel and sound. The reason I've initially connected the lights to the rear wheels is because the emergency brake light comes on with the ABS light, and they are only on the rear wheels. Both the ABS and emergency brake systems are working fine, so I don't think the problem is with either system, but with the electrical connection to the lights. That said, I've never seen this happen before so I'm just trying to eliminate and isolate possibilities.

 

I had 2 separate probems with my ABS.
First, the wire harness from the frame to the rear axles sesor on the pumpkin was weak, internal broken, so i had problems even with a new sensor.
Second, the ABS unit itself had cold solder points internally, at the beginning it went back to work when i wiggled the connector at the unit, lasted a couple potholes until it went out again.
Solution was to send the unit to an electronic geek that opened it and resoldered it professionally.

Without proper diagnosis you probably on the way to just throw parts at it.

 

Digital Auto Technologies in Marlboro, Ca repairs the Dodge Ram ABS modules for this exact problem. They work intermittently and then pop up the trouble codes. They open up the modules and re flow the solder joints on the high current components with a higher temp solder and guarantee their work.

 

Good to know!!
I keep that in mind if I run trouble again.

 

Thanks for the info, guys. I just had the right combination of good weather, free time and no road construction crews blocking my street so I took advantage of the opportunity and changed out my APPS to the new Timbo that's been sitting on the table. For what it's worth, that was an easy fix, and the voltage was .667, so I didn't even have to set it. So now it's on to the next minor but aggravating problem. At least the list is short now.

Since the bearings are fairly new and the problem is limited to cold weather I'm really hoping that isn't the source. I'll start with the rear wheel speed sensor and work from there. I just checked for codes, and the only code is the P2121 left over from the APPS; nothing to do with the brakes at all. If it turns out to be the unit I at least know of a shop that can repair it now. I'm assuming that the unit in question is the CAB (Controller Antilock Brakes)?

 

Here is the link for repair options if you are getting the power failure trouble codes for ABS.

http://stores.digitalautotech.com/98-08-dodge-ram-durango-pickup-abs-module-repair/

 

To read the ABS Codes you need a sophisticated scanner.
They dont show up at the cluster or at the common chepo scanners.

For sure you have stored faults, they are there at the moment the cluster light lights on and stored.
The light may go of, but the faults never erase by them self.

 

Well that sucks. Is it the kind of scanner a basic auto repair shop would have, or is it one of those things only dealers are likely to have?

 

To my knowledge only the Autoenginuity and maybe the Snapon reads it, and of course the wiTech.

 

If I have to remove the ABS unit and send it out to be fixed are there any surprises in removing it? I'm assuming it's the box between the firewall and the driver side battery, held in place with the Torx screws. Is that correct? Based on the other current ABS thread it sounds like the brakes will continue to function normally, albeit without the ABS function.

 

Yes just loosen the Torx Screws then you can pull the electric part of the unit and send it to Cali.

 

I may end up doing that quicker than I was planning to. Last week I noticed that my Prodigy brake controller was showing "NC" (Not Connected) as I was driving without a trailer. Normal operation is showing 1 or 2 dots, depending on the boost setting. Because it was 15 years old I went ahead and upgraded to a new Tekonsha P3, which arrived today. I connected it to the existing connector harness (came with the truck as part of the tow package) and am getting the equivalent message on the new unit. Somehow, it thinks there should be a trailer connected, but is not connected properly. None of the associated fuses are blown (I believe they are #1, #4 and #35).

Logically, I don't see how the ABS/Brake lights coming on are associated with the brake controller thinking that it is not connected, but I have to wonder. The ABS/Brake light problem has been going on a couple of years, while the "NC" on the brake controller only started about 2 weeks ago. Should I proceed on the theory that they are connected, or is there another probable reason why the brake controller is acting up?

 

I just lived a month of hell with the ABS/Brake Light on my 2003 Dodge Ram. The code reader I have access to did read the fault code for the controller (LF Sensor Failure). First inspect the ABS Controller plugs. I read in another blog corrosion is common in this area. Plug C1 on my truck pins 12, 13, and 14 had severe corrosion. Sent my controller to a repair facility and they wouldn't repair it due to corrosion.

I needed plugs C1 and C2 replaced. I found another facility that would do it if they had the parts. So I sent them my controller and a controller out of a wrecked truck and they were able to cannibalize the parts to repair my unit. They also repaired a few solder joints on the board. The repairs cost $50. From the same wrecked truck I cut the C1 plug and enough wire to repair the 3 pins on my truck harness. I replaced the 3 pins and the plug to remove all of the corrosion.

Installed new controller and it checks good now. I left out all of the wire shooting and I slaved in at least 2 different LF Wheel speed sensors into the left front with no change.

Warning do not try to use an ABS controller out of another truck. ABS controllers are VIN coded to that specific vehicle and will cause nothing from problems. I did find a company where you can but a Kelsey Hayes 325 and they will program your VIN into it. If for some reason your ABS Controller is not rebuildable. https://www.autoecu.com/contact/ is the company you can purchase one if required. ABS Controllers for the 2003 Dodge Ram is a discontinued item from Dodge/Ram. The dealer can't erase VIN codes on VIN coded parts. They can only install VIN numbers.

 

I just pulled the plugs on the ABS unit, but didn't see any corrosion on either plug or the connectors. I did see what looked like dust in and around the plugs on the ABS unit. So as a precaution I hit both the plugs and connectors with a bit of Deoxit D5 before reconnecting them. Did it work? Most likely I won't know until the weather changes and we have a few days in the lower 40's or 50's. I stopped at a dealer about a month ago to have them clear the codes for an ECM problem I was dealing with. I asked them to check for ABS codes, and they didn't see any at the time. Not sure what kind of scanner they were using, but it was about the size of a 3x5 index card. If the problem comes back I guess I'll have to send it out and have it checked for cold solder joints.

 

You may be fighting a cold solder joint. If you have verified the sensors, wiring, and power/grounds are all good. It may be time to send it in for repair. I have access to an Autel MaxiCom MK808BT code reader. It reads all of the codes beyond just the ECM. The dealer probably used a DRB III scanner. The problem with this is the DRB III scanner is no longer supported. My dealer told me up front that theirs is temperamental.

Cerberusiam is correct. You can use another controller but you have to have the VIN wiped and your VIN loaded. He is also correct, in finding the guy who can do it is like trying to find a unicorn. The dealer can only install VIN numbers, the dealer cannot erase VIN codes. The link I provided is the first company I found that I could buy a refurbished controller and they could install my VIN on it. I didn't have to use them but they have the magic to erase and install VIN codes on the ABS Controller.

I used SIA Electronics out of Illinois to rebuild my controller (http://siaelec.com/). They were able to cannibalize the plugs I needed to repair mine. They don't install VINs or deal with software. But you won't need to on your unit.

 

Hmmm... I put another ABS controller in my truck from an junkyard because I tried to solder/repair mine and destroyed it taking it apart. Nothing ventured, nothing gained...
The one from the junkyard has not thrown a code yet (that I can see). 4 months and a long trip since.

 

I've heard it work for some folks. It didn't in my case. I used one out of a 2 wheel drive gas truck. May have been the difference. I pulled two from a salvage yard and took one apart too. I destroyed it also. I pulled the DC motor plug right out of the board. The trick is breaking the bonding on the DC plug and the plastic casing. If you can figure that out we could all do our own repairs.