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Discussion Starter #1
I'm getting creative with electronics on my 2001 V6 quad cab Dakota. Follow me on this. Only problem this truck has is high beam on left head light does not work. All else work.. chimes, dome light, headlight timer, all other beams on headlights.
In trouble shooting I found all headlight beam distribution goes through the Central Timer Module (CTM). There is one lead/wire coming from the head light S/W to the Multi Function Switch (for upper/lower beam selection) then to the CTM. From the CTM 4 wires come out to headlight bulbs. 1 wire each for hi beam left/right, low beam left/right. I applied 12V to wire going from CTM to left hi beam element and it lit up just great!
So I got to thinking:censored:. The hi beam on right side works why couldn't I jumper from the hi beam on right to hi beam on left? So I did. I jumped wires at the output of CTM which is located on drivers side kick panel at the left of your foot. Works fine. I left hi beams on (motor not running} but they timed out aft 10 min and shut off. Did that 3 times all was ok. I plan on driving with H/L on all the time to see if it stays OK.
What do you guys think? Here is address to schematic of H/L ckt. You will see the the CTM on left towards top.
 

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Well, I'd add a relay harness ANYWAY to get the wire a heavier gauge and shorter to improve the output.

Did you check to see if the CTM was outputting the voltage on high, or not?

RwP
 

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Great job on the troubleshooting and a creative solution. There are separate drivers in the CTM for each head lamp (left, right, low, high), so you are using one driver for both high beam lamps. If it works, you should be OK. But Ralph makes a good point to add a relay in there so the driver only has to activate the relay, not both lamps.
 

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Other than that after troubleshooting to get the results that you got my first instinct would be to replace the CTM with another one, I agree with the "add a relay" comments. The only caveat is that I don't know if the CTM senses outgoing current and takes some action if it knows the high beam is switched on, but it is not sending appropriate current to illuminate at least one headlight. I hope it's not that sophisticated.
 

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Discussion Starter #5
Hey, thanks for the replies!
I did check for volts output for left hi beam coming out of the CTM. There was none.
I did consider replacing CTM but a used one on Ebay is $150 then require flash at dealer. Sometimes they work and other times not. I didn't check new price but have heard $300+. If I fry mine I can always replace it. Hope it doesn't take out something else. :eek:

The relay is a good idea. I'm going to look into that.
I'm amazed at how small the wire to the high headlight element is coming out of CTM. A 20 gage or less. According to my calculations on halogen lamps 65 watts/12 volts = 5.4 amps draw. Wow, can that be right on such a small wire?
 

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Hey, thanks for the replies!
I did check for volts output for left hi beam coming out of the CTM. There was none.
I did consider replacing CTM but a used one on Ebay is $150 then require flash at dealer. Sometimes they work and other times not. I didn't check new price but have heard $300+. If I fry mine I can always replace it. Hope it doesn't take out something else. :eek:

The relay is a good idea. I'm going to look into that.
I'm amazed at how small the wire to the high headlight element is coming out of CTM. A 20 gage or less. According to my calculations on halogen lamps 65 watts/12 volts = 5.4 amps draw. Wow, can that be right on such a small wire?
That's why you put a relay harness on it ... let the good output control the harness (so the right side headlight plug), and then the CTM is only driving a few milliamps on that wire.

I think it'll be 18ga; but yes - that's not uncommon in car companies to undersize the wire like that.

Do be aware you're now pulling about 11a through that wire ...

RwP
 

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Hey, thanks for the replies!
I did check for volts output for left hi beam coming out of the CTM. There was none.
I did consider replacing CTM but a used one on Ebay is $150 then require flash at dealer. Sometimes they work and other times not. I didn't check new price but have heard $300+. If I fry mine I can always replace it. Hope it doesn't take out something else. :eek:

The relay is a good idea. I'm going to look into that.
I'm amazed at how small the wire to the high headlight element is coming out of CTM. A 20 gage or less. According to my calculations on halogen lamps 65 watts/12 volts = 5.4 amps draw. Wow, can that be right on such a small wire?
I got a used CTM on eBay for about $50 if I remember right, but my keyfob won't unlock the truck anymore. It's not a big deal for me since I don't drive it too much. The power locks still work from the inside though.
 

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Discussion Starter #8
Thanks for that regork. I'm installing the relay now but will keep that in mind if my CTM bites the dust big time.
 
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