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Discussion Starter #1
Well my good luck streak has hit a minor bump.

I have no to varing voltage at my tow connection, connection.
I’ve unplugged the socket from behind the bumper 7/4 pin connection and I have varing low voltage outputs with the lights on.
I’ve checked the fuses, they are ok. I’ve checked and cleaned what grounds I can find...those look good too.
The posts on the connection that plug into the back of the 7/4 pin conector are super clean with no sign of corrosion.
I’m far from what one might call an “electrical guy”.
I’ve had one “electrical guy” have a quick crack at it with no luck.
Im basically looking for any tips or previous experience with this issue. I do not want to bring the truck into the dealer to waste hours and hours to come up with nothing. That is last resort.

Trailer has been tested and works perfect.
Tail lights on the truck work fine too..and I beleive that is a totally separate circuit.

Any help would be great!
 

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Is it all of the pins, Including the +12 terminal? You may have to trace the harness up to the front of the truck.
If it's just the trailer brake, the output is variable based on vehicle speed. I believe this applies to the manual lever also.
 

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Discussion Starter #3
the only 12+ volts i get is at the #5 terminal on the truck (left turn, brake).
i will double check everything after work tonight.
 

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Not going to belittle your ability to check fuses, but there is a section for trailer fuses alone in the panel. Pull them out one at a time and check them with a meter, lowest Ohm setting. You get a zero or very close to it, fuse is good. If there's no reading, fuse is bad. Let us know how you make out.
 

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Discussion Starter #5
hey man...i’ll take any help i can get. im not offended.
so ya...there are 2 20amp fuses i found. one labled tow/left brake and one labled tow/right brake....if i remember correctly.
i did pull both these fuses, but only gave them a visual and they looked fine, but i will check resistance on them tonight.
thanks.

i desperately need to get this sorted put and fast...anyone ever install one of those tow light power moduals before. i see one on amazon for $50 and it has internal overload protection or circuit breaker of some sort. easy, yet half assed fix??
 

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I see a couple of relay in addition to the fuses ,
maybe they are not pushed in all the way ...??
fuses 28 ,29 ,30 ,81 ,53 , 4 or 5 relays used for different trailer related stuff
including the trailer brakes control as seen in PDF files.
..
I have 2 wiring diagrams , I don't know the difference between the 2 ..:confused:
 

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hey man...i’ll take any help i can get. im not offended.
so ya...there are 2 20amp fuses i found. one labled tow/left brake and one labled tow/right brake....if i remember correctly.
i did pull both these fuses, but only gave them a visual and they looked fine, but i will check resistance on them tonight.
thanks.

i desperately need to get this sorted put and fast...anyone ever install one of those tow light power moduals before. i see one on amazon for $50 and it has internal overload protection or circuit breaker of some sort. easy, yet half assed fix??
The tow modules were an ideal fix for the older RAMs, if you had a short in the trailer system, you had to take the truck in to get it reset, max of 3 times and then the whole module had to be changed at around $700. If the tow module has lower value fuses then they would blow before the truck ones do which would be good.
 

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there are 2 20amp fuses i found. one labled tow/left brake and one labled tow/right brake....if i remember correctly.
i did pull both these fuses, but only gave them a visual and they looked fine, but i will check resistance on them tonight.
thanks.
A cheat sheet of the fuse number, rating and fuse type for the trailer 7 pin:

F53 ATR 20 amp Left Trailer lights
F81 ATR 20 amp Right Trailer lights
F29 FFM 20 amp Trailer Park lights
F28 FFM 20 amp Trailer Back up lights
F30 FFM 30 amp Direct from battery
F11 J Case 30 amp Brake Lever
F87 ATR 10 amp ITBM module
 

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Discussion Starter #10
thanks Crash.

i just did some quick minor tests.
all related fuses are in place and are in good working order...tested with the mulitmeter.
i have perfect continuity at 0-0.001 ohms from the ground terminal on the truck tow connection, to the (-) post on the battery...connected with a long peice of wire i attached to it.
when the truck and lights are on. i have a normal 14v of power when the brake is pressed to the left brake/blinker terminal only.
everything else is showing like .20 to .80v when truck is on or off.... whats up with that??

also, is there a terminal fed directly from the (+) side of the battery?
if so i should have +12V there at all times right?
i guess i should check that for continuity as well??
 

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is there a terminal fed directly from the (+) side of the battery?
if so i should have +12V there at all times right?
i guess i should check that for continuity as well??
The top right blade in the connector is the +12 V connection. It should be hot all the time. Mine is tapped to power the lights inside my topper.
It's printed on the cover of the 7 pin but this is a little easier to see:
 

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thanks Crash.
when the truck and lights are on. i have a normal 14v of power when the brake is pressed to the left brake/blinker terminal only.
everything else is showing like .20 to .80v when truck is on or off.... whats up with that??
I'm beginning to wonder if the relays shown by K in the schematics are shot for the right brake/signal and park. You can switch the left relay out and put it in the right or park one to check the relays. Doesn't hurt to try.
 

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I had an epiphany ....well ok maybe not quite that extreme but something I would try if you haven't already been doing while troubleshooting.
Pull the plug out of the back of the 7 pin plug in the bumper and test that directly.
If that comes up crickets, I might be able to get some screenshots of wire harness routings on Friday.
 

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Discussion Starter #14
thanks guys.

i did test from the connection behind the 7/4 pin connector. which looks super clean and corrosion free.

about the relays...i dont know which realy is for which side.
the listed relays/fuses and their location etched on the backside of the fuse box lid doesnt mention anything to do with the tow lights at all.
let me have another look at that wire diagram but im pretty sure it doesnt show a location like it does for the fuses.
 

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Discussion Starter #15
i wish i knew how to post pictures.

a few queations about the wiring diagram posted a few posts back.
what does the dotted/dashed lines represent between various wires?
for example....half way up the red/brown/black/green/yellow wires, there is a dashed line and it says INLINE-BODY/CHASSIS beside it. is this a plug connection of some sort? somewhere I can do some testing on..if I can find it.
also the light blue shadded areas....are these harness conmections??
sorry for the stupid questions...im really trying to learn this crap lol
 

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a few queations about the wiring diagram posted a few posts back.
what does the dotted/dashed lines represent between various wires?
for example....half way up the red/brown/black/green/yellow wires, there is a dashed line and it says INLINE-BODY/CHASSIS beside it. is this a plug connection of some sort? somewhere I can do some testing on..if I can find it.
also the light blue shadded areas....are these harness conmections??
sorry for the stupid questions...im really trying to learn this crap lol
There is never a stupid question except the one not asked...and I just had another idea what to look at (due in part to your questions)
The blue shaded areas is something in the truck, there is usually a description like Assembly Power Distribution Center (remember this it will be important)
The INLINE-BODY/CHASSIS is a connector somewhere located in the vehicle, as stated earlier I might be able to to get a pic of where this is located but I don't think it will be needed.
The dotted lines represent a plug that all of those wires are located in. Here's where I hope this all come together for you. You said everything but the left turn/stop is dead, look at the first diagram. The ones that dead are all in the C7 plug on the back of the Assembly Power Distribution Center, the left side one is in the C5 plug. The numbers in the squares is the pin number of the plugs. Your probably going to have to pull the fuse block to get to this.
If I could I would come by drink your beer(lol) and help you dig into this one, curiosity has the best of me now.
 

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Discussion Starter #17
well shit...if that dont make sense, nothing does.
good call on the troubled wires all in one plug/connection.
i’ll definitely get looking at those hopefully tonight.
i’m learing a lot here which is always cool.
i’ll report back asap.

my beers are always cold! ����
 

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one bit of info , just noticed the wiring diagram is for a 2017 ,
could it be different in model year 2015 ???
..

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No numbers on the 2 relay , but ,
left side associated fuse : #12 C5
right side associated fuse :#33 C7
 

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one bit of info , just noticed the wiring diagram is for a 2017 ,
could it be different in model year 2015 ???
No numbers on the 2 relay , but ,
left side associated fuse : #12 C5
right side associated fuse :#33 C7
I doubt there is much difference in the wiring, if anything changed it was in 2015 when the module programming changed.
The C5 #12 and C7 #33 pins go-to the coil side of the relays and are controlled from the BCM
The left turn/brake fuse is F53 and is in the C5 plug pin #34
The right side turn/brake fuse is F81 and is in the C7 plug pin #30
 

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My truck had issues w/ fuses blowing on 4 and 7 pin plugs...was trying to pull local high school band trailer...kept having issues. Don't remember fuse amps but I think was 20amps...replaced w/ 10 amps higher (30?) and fuse never blew again pulling the band trailers.

is this dangerous? IDK but my dad was a lineman for FPL and said it was nothing to ever worry about....that was 100,000 miles ago...
 
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