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I had my 2020 7.3 Tremor at the RV shop all day yesterday. I have a fifth wheel toyhauler, and had to have my trailer lifted/raised to pull somewhat level. The owner and his guys spent hours (not billed) trying to get the running lights to work. Brakes and brake lights and turn signals and reverse lights all work, but no tail lights or running lights. The trailer lights work and the fuses are all good, but the truck is not sending power to the running lights.If it matters, trailer lights are all LED.
In the manual for the truck fuse box we found a "trailer tow lighting module". The fuse for this was intact and not blown. We went through the trailer set-up on the truck, but could find nothing to turn on or off pertaining to running lights. So after checking everything out, for hours, we decided that something is probably not set correctly in the computer. This is my first Superduty, my last truck is a 99 F150, so I am totally overwhelmed with all the features and capabilities. I only have ~500 miles on my new truck, (picked it up 5 days before the C-19 shutdown), so forscan stuff is like a foreign language to me!
I will search here and on Goggle and YouTube, but put this out here first cause this is where I got all my info to order my truck. So thanks in advance and for services already rendered. Dave
Did they turn the headlight switch to on or did they just leave it on automatic? You have to have the headlights turned on for the clearance lights to work. I’m pretty sure this is the first thing a trailer place would do.
Pressing the brake peddle was to get the 12v charging working.
This sounds like a good thread for Jim Crewzer to weigh in on. 👍
Did the running lights work if the trailer is hooked to a different tow vehicle? That would be worth a shot to rule out an issue with the trailer. Right now you're assuming it's the truck (and it very well could be) but that'd be a simple check to know for sure that it's not some electrical gremlin with the trailer.
I haven’t noticed anything weird or odd in that respect on my 2020 F350. Lights on, trailer lights are on. I haven’t towed at night yet, so can’t say if they operate differently if they go on automatically, but that would seem weird. I will tow at night this week, so I will see.
someone had posted that the DRL’s turn on the trailer lights, but I haven’t seen that either. In the daylight I just have to turn the lights on to get trailer lights.
I did read something about led light being fussy with newer trucks. I had to buy a Curt 57003 Led-Compatible adapter to make my truck think a trailer was connected so I could check output on the 7-pin.
I don't think you can check the 7-pin without some kind of adapter.
Trailer running lights are functional, no voltage out of 7 pin connector. And the headlights were manually turned on. Flummoxed!!!
You won’t get voltage out of the 7pin unless a trailer is attached. (If you have a factory brake controller) Best way to test is to buy a dummy test plug and pull out test light. Or buy something like this Because it basically has the test light built in. Any auto parts store should sell something similar.
Im sure your trailer guys did all this. The Ford trailer wiring system is an over complicated piece of garbage.
Another thing I just thought of was to clean your 7 pin prongs and check the back of the connector (behind the bumper) for any corrosion. My left signal light wouldn’t work but all others did. Same situation you have going on except different lights. I cleaned everything and it worked. Truck was a few months old at the time.
Edit. Before I cleaned everything, it didn’t look very dirty.
I'll have to get a tester, but my trailer shop is a big busy shop, so I'm sure he tested it. My truck was ordered with the 5th W prep and ultimate towing package, has LED package as well as camera and TPMS package I have yet to receive(Grrrr), so it should not require an adapter to power the lights at least. We did try both the bumper socket as well as the in-bed socket.
According to Ford, you need to attach a trailer with brake lights, start the engine, and apply the truck’s service brake to activate the trailer connector +12 circuit.
See instructions from the 2020 OM below.
Our truck camper has all-LED lighting. Our truck recognizes the brake lamps, and the +12 circuit from the truck works per Ford’s instructions, although I have to increase engine idle speed a bit to deliver full voltage.
I had my 2020 7.3 Tremor at the RV shop all day yesterday. I have a fifth wheel toyhauler, and had to have my trailer lifted/raised to pull somewhat level. The owner and his guys spent hours (not billed) trying to get the running lights to work. Brakes and brake lights and turn signals and reverse lights all work, but no tail lights or running lights. The trailer lights work and the fuses are all good, but the truck is not sending power to the running lights.If it matters, trailer lights are all LED.
In the manual for the truck fuse box we found a "trailer tow lighting module". The fuse for this was intact and not blown. We went through the trailer set-up on the truck, but could find nothing to turn on or off pertaining to running lights. So after checking everything out, for hours, we decided that something is probably not set correctly in the computer. This is my first Superduty, my last truck is a 99 F150, so I am totally overwhelmed with all the features and capabilities. I only have ~500 miles on my new truck, (picked it up 5 days before the C-19 shutdown), so forscan stuff is like a foreign language to me!
I will search here and on Goggle and YouTube, but put this out here first cause this is where I got all my info to order my truck. So thanks in advance and for services already rendered. Dave
Originally Posted by Smokeat
Trailer running lights are functional, no voltage out of 7 pin connector. And the headlights were manually turned on. Flummoxed!!!
Originally Posted by Smokeat
I'll have to get a tester, but my trailer shop is a big busy shop, so I'm sure he tested it. My truck was ordered with the 5th W prep and ultimate towing package, has LED package as well as camera and TPMS package I have yet to receive(Grrrr), so it should not require an adapter to power the lights at least. We did try both the bumper socket as well as the in-bed socket.
"I have a fifth wheel toyhauler"
Did you own this 5th wheel toyhauler PRIOR to your ownership of the 2020 Temor?
If so, what truck did you use to tow it?
Did you experience any problems with the trailer's lights towing it with that previous truck?
"The trailer lights work"
How were the trailer lights tested?
With a different truck?
With 12v power manually applied directly to the 1 o'clock positioned flat blade receptacle on the trailer 7 Way RV connector, and ground manually applied to the 5 o'clock flat blade receptacle of same trailer connector?
Or were different pin locations on the trailer pin powered to verify function of the trailer's running lights independent from the Tremor?
"no voltage out of 7 pin connector"
What does this sentence mean, more specifically?
No voltage on the trailer battery charge circuit located at the 1 o'clock positioned flat blade PIN on the Tremor? (Note that this 1 o'clock pin on the truck connector does NOT mate with the 1 o'clock receptacle on the trailer connector).
No voltage on any pin of the Tremor connector? (Then how could the turn signals and brake lights and reverse lamps work?)
If your toy hauler can plug into a different truck, and all the lights work fine, then the issue isn't likely to be the trailer harness. But the information as reported thus far does not yet establish that the trailer's harness, as it now sits, after the work modifying the ride height of the trailer, is verified to be sound and wired correctly. The trailer's lights have been checked, but without information as to how those lights were checked. Therefore, the possibility of an inadvertent error imposed on the trailer's harness, connector, or junction box cannot be ruled out without further clarification.
Since the trailer was modified, and not the truck, I would be more inclined to look more critically at the element that was messed with, which is the trailer. Once the trailer is ruled out as sound by plugging it into a different truck, or testing the function of lights through the trailer connector pin, with knowledge of which pin serves which function in a standard RV 7 way flat blade interconnect, then, and only then, would I look more critically at the Tremor. If you are already at this stage of the game, then forgive my pedantry, because the information provided did not make that abundantly clear.
During the COVID stay at home lockdown, I built the trailer wiring harness on a 2019 F-550 originally equipped with the factory Ford IBTC (Integrated Trailer Brake Controller), with a view in mind to accommodate every possible trailer connector lurking in any equipment rental yard... 7 way RV flat, 7 way commercial round, 6 way round, 5 way flat, 4 way flat, and a test connector. Truck is prepared. So I have very recent familiarity with 2019 model Ford trailer wiring, and did not encounter any functional issues with the running lights requiring enabling contingencies like turning the key with the brake pedal depressed, or plugging in a trailer, etc.
Thanks Everyone! Just got back from the trailer. Hooked up my buddies 2015 Silverado 2500 (I know, I hang out with people with questionable taste!) and a curiously exact thing happened when we first turned on the headlights on the Chevy and the Ford both. At the first try of each, I watched the running light turn on for a half second, then off. We could not replicate this with either vehicle, no matter if we took out the key, unplugged the trailer, cursed or prayed! Just happened the very first time each vehicle was attached to the trailer. Dave
P.S., Thanks Jim, I am going out now to check fuse #26. I'll report back.
I’d check grounding on the trailer since it isn’t working on either vehicle. I have this issue after changing out a brake light I broke. I need to troubleshoot it, but I think it is a grounding issue. I also tried a second vehicle and it is definitely my trailer. Just a thought.
