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Nelson Harnes Causing Problems?


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I had another thread going concerning a Reduced Engine Power problem. The truck had cooled down and I started it, ran fine. I revved it and turned on all accessories A/C ,high beams, stereo, defogger and my battery voltage never went below 12,7 when the fans kicked on but only for a second. Everything was fine until the truck warmed up to about 185 then I hit the gas hard and it went to REP mode and died. I have already changed out the PCM,pedal, and TB with spares I had. I loaned my extra TAC module and another TB to a member here, even paid shipping and he won't return it...nice guy HUH? Anyhow I was messing around with it after it did that and I found something odd. If the truck is turned off key out and I pull back on the high beams both the high beams and the E-fans come on...WTF? This is something new.

 

Dave

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Hmm, I've never had a problem with my harness, although I can vouch for the drop in voltage when they come on. But that would be expected because of how much amps the fans typically draw. One weird thing I did have, was one fan would run in both low speed, and high speed once it reached the temperature I set it. While the other would only run in low speed and never high. I fixed this by running them both off of the one line that worked in both low speed and high. Never had any problems after that, not even with both fans (around 30 amps) going through the one fan harness connector.

Edited by Professiona1 m0d
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Yup, the contacts on the relays kept on burning up on my nelson harness for the efans, however I think his proplem is more serious than just the efan harness. The nelson harness shouldn't have anything to do with his headlights.

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I am doing a swap and while combing over many wiring diagrams I see there are some differences in the wiring in the trucks. If this harness connects to the PCM then I would check if the right pin is getting used and providing the correct signal.

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My e-fans have been on there for over a year with no problems. I did recently install my 4th transmission though. Maybe I pinched something (unlikely) I'm gonna dig into it further today. I'm thinking I got water somewhere when I sprayed the engine off but that was over a week ago.

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I am doing a swap and while combing over many wiring diagrams I see there are some differences in the wiring in the trucks. If this harness connects to the PCM then I would check if the right pin is getting used and providing the correct signal.

 

When I installed my updated 05 plus wiring harness, and pulled my old one out, they where the same with the exception of the added relay and fuse block needed to support the e-fans, and the plug that should plug into the output harness of the PCM to trigger the fans to come on. I just intalled two new pins to the PCM, ran two new wires to the fan wiring harness plug and spilced in. I also ran two more wires spliced into the same location and ran into the cab for switches, that way I can manually turn on my fans with out having the truck on or with out the use of EFILive.

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Go to this link and look on page 40

 

2004DTC list

 

"Indicates that the TAC Module has detected a throttle positioning error

OR

Either Processor cannot determine throttle positioning"

 

From another source

 

P1516

IMRC Input Error (Bank 1)

 

P1517

IMRC Input Error (Bank 2)

 

P1518

Intake Manifold Runner Control (Stuck Open)

 

 

CD

Edited by cadowns
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I took the cover off of the fuse box and unlatched it. I look underneath and moved some stuff around. I also crawled under the truck to make sure I didn't pinch any wires with the transmission. I left it sit with the fuse box cover off most of the day. It seems ok but I still don't trust it 100%. It was somehow backfeeding thru the headlight switch (when you pull it to bright) and if I hit the haigh beams while the truck was idling it would die. I imagine something was wet? I was also beginning to worry that my BCM was bad. I still don't know exactly what fixed it or if it really is fixed. I'm really starting to lose patience with my truck at this point.

As for the harness I had no problems with it for the last year and everything seems ok now and they are controlled thru the pcm but I was told that 03 and down trucks don't have the capability to run the fans correctly unless you use the 3 relay setup like the Nelson harness. Thanks for all of the replies.

 

Dave

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I took the cover off of the fuse box and unlatched it. I look underneath and moved some stuff around. I also crawled under the truck to make sure I didn't pinch any wires with the transmission. I left it sit with the fuse box cover off most of the day. It seems ok but I still don't trust it 100%. It was somehow backfeeding thru the headlight switch (when you pull it to bright) and if I hit the haigh beams while the truck was idling it would die. I imagine something was wet? I was also beginning to worry that my BCM was bad. I still don't know exactly what fixed it or if it really is fixed. I'm really starting to lose patience with my truck at this point.

As for the harness I had no problems with it for the last year and everything seems ok now and they are controlled thru the pcm but I was told that 03 and down trucks don't have the capability to run the fans correctly unless you use the 3 relay setup like the Nelson harness. Thanks for all of the replies.

 

Dave

 

>02 do not have the capability to run fans both in high and low settings. 03 plus PCM do have the capability to run the fans, you just have to run two wires to the PCM, pins 33 and 42 if I remember right. To use the nelson harness you will have to modify it so that the high speed setting no longer gets triggered by the A/C positive signal. Then everything will be good.

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Well, I thought I had my problem fixed but apparently not. I threw codes P1516 P1518 P0102 P0220 all related. My truck is doing the wierd thing again where if Ipull back on the turn signal lever to the "flash to pass" position it cause all of my accessories: fans, lights, fuel pump, etc to come on like there is a short somewhere. Wierd thing is I cannot clear the REP mode unless I manually turn the headlights off before I start it and it will stay out of REP mode as long as the fans don't kick on. I don't think it's a overall power draw problem but whatever is shorted is causing a voltage drop at the TAC/TB. I consider myself proficent with a wrench and have done everything to this truck: swapped engines, trans, etc but the bundle of wires under the fuse box and at the PCM leave me some what dumbfounded. Now I wish my truck wasn't so modded cause I really can't take it to the dealer now not to mention that the problem is intermittant. DOH!

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