Hey guys, I'm new here and I'm in serious need of help

My 2002 Dodge Dakota Sport (4x4 6cyl) driver side head lamp won't work, hi or low beam. Passenger side works fine on both

What we've already tried:

- replaced headlight with known working (took out of passenger side where it worked fine, did not work on driver side), we also replaced with a new bulb (both sides, confirmed working on passenger side)

- Confirmed that there is no voltage at the socket when headlights are on, we get 12 Volts on passenger side, none on driver side this is both Hi and low beam

- Confirmed that we get 0 Ohms when grounded directly to the battery

- confirmed there are no blown fuses in fuse box next to drivers side door, did the same with fuse box in engine compartment. Although I'm not sure there IS a fuse for the headlights, we had head lights on pulled every fuse one at a time and the only time the passenger light went off was when we pulled CTM A fuse (Central Timing?)


I'm at the end of my rope here, I can't find a fuse for the passenger head light, I can't find anything that would cause the driver side to go out only (no other electrical issues at all in the truck). I'm about to take it to a dealer to "troubleshoot" but don't really have the money for them to poke around for a few hours on my dime

any suggestions or help that anyone can provide would be great!

 

Welcome to DodgeForum!!

I'll move this to the 2nd Gen Dakota section for you.

 

Welcome to the Forum...

It's probably the Central Timer Module. I just read in my Dakota Service Manual that there are 2 inputs from the headlight switch to the CTM, one for both left and right low beams and one for the left and right high beams. Then there are 4 positive outputs from the CTM to the headlights, left high beam, left low beam, right high beam and right low beam.

When you turn the headlight switch on it sends a ground through the multi-function switch then that sends a ground input to the CTM for the headlights to turn on. The CTM sends positive voltage out to the lights, on the low or high beam outputs (Dodge calls the outputs a driver) depending on the selection on the multi-function switch.

The only way to test the CTM to be certain is at the Dodge dealer with the DRB scan tool. The outputs to the headlights are not fused. The only fuse the manual shows that is related to the headlights is a 20 amp fuse labeled "H" at the power distribution center. That may be the one that caused the passenger side light to go out when you removed it.

With the passenger's side light working OK, I doubt the multifunction switch or the headlight switch are at fault here. I would be willing to bet you have a bad CTM, it is a pretty common problem on Dakota's. I have a theory that it happens more often up north where it gets cold and there is a lot more of a static charge built up in the cab of the truck, from using the heat a lot. The CTM is pretty sensitive to static charge.

I have read that it runs anywhere from 200 to 400 bucks to diagnose and replace a CTM at the dealer. But, if you have a base or sport model truck without all the power options, you can buy the new CTM at the dealer and replace it yourself. There is no learn procedure when you don't have keyless entry, power windows and locks, etc. But if you do have the power options, the dealer has to program the new CTM with the DRB scan tool. If you don't have keyless entry, you could buy a new CTM and plug it in yourself and see if everything works OK. If you wind up needing a new CTM and have keyless entry, be sure you take both remote fobs with you so the dealer can program them to the new CTM. Otherwise, the keyless entry will not work.

The CTM is located in the driver's kick panel. It's a slim black plastic box with 3 plugs and about 100 wires going to it. The CTM controls nearly every single electical accessory function on your truck. If you don't have the power options, you *might* be able to save some money if you get a CTM from a junk yard and plug it back in yourself. But the CTM has to come from a donor truck that has the same options as your own truck. Personally, I think buying electrical parts from a junk yard is taking a big gamble and you are better off buying electrical parts from the dealer or at least new from an online supplier. But sometimes you can save money on a salvage part.

Good luck and let us know what happens with it.

Jimmy

 

yeah I was afraid it was going to be the CTM but I am still baffled by how the only thing impacted would be the driver said head light, I have no other electrical problems anywhere. We already removed the CTM and checked to ensure no wires were loose or anything and they aren't.

Do you by chance know which wires going in are the headlight? I have a Chiltons guide with a wiring diagram but it is completely useless so we don't even know which wires to be looking at out of the 100+ that go through there

I do have power windows and doors but no keyless entry so I assume I'll be looking for a replacement CTM

just curious - if I find another model with the same power options, does it still need to be reprogrammed or can it just be swapped out?

 

I'm at work now, and my service manual is at home. I can post back and tell you which wire is for the inputs to the CTM for the lights, but it won't be until about 7:00 tonight, Eastern time.

I think if you find a CTM from a truck with the same options as yours, it would work without being reprogrammed. There are only 2 CTM part numbers anyway, one for trucks with no power options and one for the trucks that came with power windows, locks, keyless, cruise, etc. You should be able to unplug the old and plug in the new CTM and the accessory functions should all be the same. Hopefully the junk yard or seller would giv you your money back if it didn't work, or let you try it in their parking lot before you pay for it.

The CTM is a strange and fickle part. I have heard and read a lot of different reasons for replacing them. They seem to be pretty sensitive to voltage and static shock problems. The reason your passenger light still works is because the CTM contains relays for output to each headlight individually. The relay/driver for the passenger light is still OK so that light still works. When one component in the CTM fails, everything else can still work. but I have also heard of other CTM failures where multiple electrical components stop working because of internal problems with the CTM. And CTM failure seems to be a lot more prevalent on trucks that have the power options.

Jimmy

 

I was thinking about this problem, and I don't see why you couldn't tap into the negative input at the CTM for the headlight switch and then cut the wire for the driver's side headlight low beam output from the CTM. Then just wire in a plain old 30 amp Bosch relay and let it switch power to the driver's side headlight low beam wire.

I have never seen the innards of a CTM but I would be willing to bet the headlight relays, window relays and doorlock relays are all just Omron mini-relays on the circuit board of the CTM. I bet it would work to wire in your own Bosch relay like this:

Terminal 85 to the negative headlight trigger wire from the headlight switch
Terminals 86 and 87 to 12 volts + from the battery, fuse it at 20 amps
Terminal 30 to the wire going out to the driver's headlight
No connection on terminal 87a

The CTM has inputs (most of them are negative) and outputs (most of them are positive). A majority of the cicuits in our Dakota's are controlled by switching ground one way or another to make the circuit and/or components operate. But when you get down to it at the headlight, the light operates on plain old 12 volts and ground. I would bet the Bosch relay fix would work and get you by for a while if money is tight right now.

I can send you the wire colors when I get home. If you try it this way and it works it could save you money. Not to be a smart aleck about it but I am taking no responsibility for any damage it might cause. This is just an idea I had, but I think it would work because all you are doing is bypassing the internal relay in the CTM for the left low beam.

Jimmy

Jimmy

 

I can definitely give that a try... worse case scenario it fries the CTM and I have to replace it... which I already have to do anyway right?

I was actually thinking about just tapping into the passenger side headlight wires and running it over and tapping it ton the driver side as well... should work right?

 

I wouldn't do it that way. The headlights each have their own separate and independent high and low beam power wires, all coming from the CTM. A total of 4 different wires with 4 different colors. This tells me there are 4 different outputs or relays in the CTM. This is why I think that bypassing the internal left low beam relay with an outboard Bosch relay will work.

I think the high beams would still work too because according to the service manual there is a separate wire for power output to the low beam headlights and a separate wire for power to the high beam headlights on each side of the truck. But if you try splicing the left low beam to the right low beam, it could be too much of an electrical load on the circuit and burn that part of the CTM out too. Plus the lights would be dimmer and not as bright due to the increased load across two lights instead of one.

 

Wouldn't I want to do it on the coming in side where the lights are still one channel for left and one for right?

 

Input to the CTM is one wire for both low beams on and another wire for both high beams on. The inputs come from the headlight switch and are run through the multi-function switch then out to the input side of the CTM. The CTM uses those ground inputs to trigger the internal relays for low and high beams. But according to the service manual there are 4 separate circuits from the CTM for the lights. Left low beam, left high beam, right low beam and right high beam. I remember this from reading the manual last night. It had 4 outputs on 4 separate and different colored wires for each output. The ground input just triggers the internal relays, and which relay is energized depends on the position of the multi-function switch, whether it is on high or low beam. The splitting of the input for left and right is done internally in the CTM.

There is a sticky topic at the top of the Second Generation page here where you can download the 2001 Service Manual. That is the manual I use and it should be the same for your 2002. I use the Haynes book for my truck too, it might have better info that the Chilton's you are using. I got the Dodge manual a few years ago when a guy posted it on here to download for free. It was here for a few weeks and then some security guy from Chrysler made him take it down because it is copyrighted. I have not tried the download procedure in the sticky, I have had no reason to. I don't know if it has been changed to a different hosting site or what but you might try the link and see if you can download the manual too. If so, it may help you. There is a whole chapter just for wiring diagrams.

Jimmy