Turn signal light always on. Why?

[tab380]

After Sears replaced my battery, I noticed my drivers side rear turn signal light was on after the truck was turned off. When I came back to the truck later, it was off. This would happen intimately, sometimes its dim and sometimes its bright, but I would forget about it and did not do anything about it.
The last few days its on all the time and bright. I had to remove the tail light when parked at home so it would not run the battery down. I took it to Dodge on Sat. and the tech thinks its a module under the dash that cost $500.00 just for the part plus labor but wanted to get the reg. Sprinter tech to look at it when he is working before they ordered a part that they could not return.
I AM NOT GOING TO PAY 5 OR 600.00 TO FIX A LIGHT.:yell::censored: Has any one else had this problem and had it fixed? can it be something else? cheap?

[lespaint2]

Funny thing is, same thing happened to me. First, I noticed that you have an aftermarket towing hitch and harness. Is that correct? If so, try to disconnect your towing wiring harness from your main battery.
Dodge towing wiring harnesses consist of six relays. They are located below the tail light on the driver's side. When I opened mine, three of the relays were corroded and wet, but I only had to replace one. Check yours for any corrosion and if neccessary, change the relay. I got mine from the Dodge parts department at the dealership. To prevent it from happening again, make sure you move the relays up and isolate them so they don't get wet.
Hope this helped!

[tab380]

Funny thing is, same thing happened to me. First, I noticed that you have an aftermarket towing hitch and harness. Is that correct? If so, try to disconnect your towing wiring harness from your main battery.
Dodge towing wiring harnesses consist of six relays. They are located below the tail light on the driver's side. When I opened mine, three of the relays were corroded and wet, but I only had to replace one. Check yours for any corrosion and if neccessary, change the relay. I got mine from the Dodge parts department at the dealership. To prevent it from happening again, make sure you move the relays up and isolate them so they don't get wet.
Hope this helped!

Can you post photo of location and relays? I looked under the truck and see the wire harness going into the bottom of the truck and pulled the plastic covers off from inside behind the tail light but do not see anything that looks like a relay.:bow:

[lespaint2]

16519

[Brian T]

I also have a 2007 2500 long and tall and had the left stop light stay on. The relays and harness were in the left rear fender well and soaking wet. There is a drain hole at the forward end of the compartment on the inside of the bottom flange. You have to look carefully for it and it was full of undercoating, grrrrrrr ! There is an access hole on the inside of the of the compartment and the two harness entered the compartment at that point. With any luck I might attach a picture.

Brian T

[jdcaples]

Thanks, Brian.

What specifically did you do to fix the "always on" problem? Replace the module?

-Jon

[tab380]

Well thanks for your PDF of the hitch wire install, I found the wire that attached to the battery and disconnected it and the light went off.:bounce: It had a in-line fuse so I removed the fuse and put the wire back on the battery.
So it is a Hitch wire problem, but I still cant find the relays but at lest I don't have to pull the tail light off at night any more. And I don't have to take it back to Dodge and pay them to find it and its not that $500.00 module they thought it was.:clapping:
Now if some one has a pic of the relays and how to get to them.:thinking:

[Brian T]

Hi Jon

We were half way through a 23,000km trip across Canada and with no plans to tow anything soon we just cut out the relay harness. Bundled up the two cables in separate water proof bags, sealed them and stuffed them back in the hole. And of course we drained the water. Checked the other side of the van and sure enough the drain hole was plugged with considerable water. There was considerable heat, as in lots, in the harness as it was frying. If left it could have been a serious problem. Have had conversations with the folks who I believe put the undercoating on and seems things will be resolved.

Also had a substantial loss of braking, I'll submit a post in a few minutes.

Brian T

[tab380]

I also have a 2007 2500 long and tall and had the left stop light stay on. The relays and harness were in the left rear fender well and soaking wet. There is a drain hole at the forward end of the compartment on the inside of the bottom flange. You have to look carefully for it and it was full of undercoating, grrrrrrr ! There is an access hole on the inside of the of the compartment and the two harness entered the compartment at that point. With any luck I might attach a picture.

Brian T

I found it:bounce: I pulled that plug in your photo and it all came out, a string of 6 relays and the last 2 were wet and green with corrosion. The 2nd to the last had a prong rusted off and a unconnected wire. going to get parts now.:cheers:

[jdcaples]

tab380,

I suspect you're pressed for time and trying to keep on making a living, but if you can spare the time for some pictures, that would be really helpful to the forum.

Brian, thanks for the info, dude. You rock!

-Jon

[Brian T]

Here's a picture of the harness we pulled out. It was beyond cleaning up and plugging in a couple new relays. Sharp side cutters looked after the problem quickly and we continued on our way. There has to be a better way to accomplish the task and get the trailer lights going again. Trust me a bunch of relays won't get stuffed in a wet hole again. The harness itself is less than stellar, and the price...... There are some things that "have been designed by idiots to be maintained by geniuses" and this setup would qualify.

And tab380, as a "Drain Doctor" my guess is you found the "Drain" hole.

Brian T

PS: finally managed to attach 3 photos. Look out the flood gates may open !

[blakej59]

I've insulated and paneled the inside of the van so I don't have access to this area(I assume behind the rear wheel). Is this something I should open up to make sure it's not wet. I've had none of these problems described in this thread.

Jim
2007 144" Low top.

[Aqua Puttana]

Brian T.,
Thanks for the pictures.

I just really can't resist commenting. I presume this is the OEM harness that was installed and that the T1N harness is similar in design.

My aftermarket trailer light module is up where it is high and dry. By the picture here (and it's just this one little harness section) the aftermarket module also has way fewer connections to go bad. I'm still thinkin' that I chose correctly when I decided on the aftermarket module.:hmmm: AP/vic
Here's a picture of the harness we pulled out. It was beyond cleaning up and plugging in a couple new relays. Sharp side cutters looked after the problem quickly and we continued on our way. There has to be a better way to accomplish the task and get the trailer lights going again. Trust me a bunch of relays won't get stuffed in a wet hole again. The harness itself is less than stellar, and the price...... There are some things that "have been designed by idiots to be maintained by geniuses" and this setup would qualify.

And tab380, as a "Drain Doctor" my guess is you found the "Drain" hole.

Brian T

PS: finally managed to attach 3 photos. Look out the flood gates may open !

[tab380]

I've insulated and paneled the inside of the van so I don't have access to this area(I assume behind the rear wheel). Is this something I should open up to make sure it's not wet. I've had none of these problems described in this thread.

Jim
2007 144" Low top.

No No, You can't access from the inside, so you don't have to remove panels and insulation. Look under the truck behind the left rear wheel well. The big 3" diameter plastic plug with the wiring harness going into it. Also look for the drain hole just behind the mud flap. stick a screw driver in it to unclog it.:thumbup:

[blakej59]

Thank you tab380.

[bikergar]

It appears that there were changes made at some period in 07 to 08 production. My OEM wiring follows the frame rails forward. I pulled the large plug behind the rear wheel and there's nothing in there. I also checked the drains on both sides and they were wide open. It would probably be a good idea to check all the drains...If I just knew where they were...:thinking: If anyone knows their location a good place to post them would be Vic's (Aqua Puttana) cheap date thread.

gary

[sailquik]

Guys,
When talking about trailer wiring in the future, PLEASE specify/differentiate if you are working with an 02-06 T1N or 07-10 NCV3.
Also differentiate if you have a 2500 series Sprinter; 3500 series Sprinter (with dual rear wheels, and much more stable as a tow vehicle); or a RV/MH conversion on a
Sprinter cab/chassis (also with dual wheels.
I see a few photos of 2500 based RVs with 18-20' + travel trailers on the back and
I cringe a bit.
A 2500 based RV has to be running near the GAVW without towing anything. Adding a significant weight trailer looks to me like the tail wagging the dog.
The T1N does not have 6 relays, just one diode block/converter that fits inside the right
rear panel up half way between the bottom of the quarter panel and the RH rear taillight
assembly. (Getting that diode block up through the tight clearnaces is about the most difficult part of an OEM factory towing harness install!)
For the poster who put in a 20- 40 amp circuit breaker..... that's scary! Wonder what else will fry before that breaker trips?
On my '06 3500 T1N installation, the electric brake controller mfg. (Valley Industries)
recommends a 10 amp auto reset breaker @ the tow vehicle battery for the trailer electric brakes and there is no additional breaker needed for the lights with the factory (Dodge/Mopar) trailer 7 way kit.
For the poster who's towing "only 3000 lbs." without brakes on the trailer... equally scary, and probably not legal in many states.
While the factory T1N harness is a pain to install, and for more than one trailer axle needs an additional #10 AWG blue wire to up the current capacity for multi axle trailer brakes, having a bunch of connections to get the "signals" for a modulite system seems to add at least that many places the Sprinter ECM can "sense" electrical plausability issues, which can cause any problem from a simple CEL.... to codes that reset when you restart 3-4 times..... to full blown LHM.
Looks like the NCV3 factory harness is even more of a pain to install (much more complex with all the relays, etc, and apparently several more wire splices to solder).
The T1N factory OEM towing harness could have been "cleaned up" even more with the addition of a "T" connector to plug the Left Rear tail light plug into the towing harness instead of the single SOLDERED wire splice into the wiring for the LH taillight assembly.
Then there would be NO soldering required for the tail/brake/clearance lights.
It would be still better if they included an "T" connector for the blue wire for the electric
brakes that would plug into the harness for the brake switch. Then there would be zero
wire splices in the entire system (unless you wish to add the #10 AWG blue wire for multi axle brakes.
I now have around 25K miles towing 2 trailers (4k-4.5k V Nose Cargo trailer and 25' 4.8k ultra light weight Jay Feather LGT travel trailer) and the lights always work perfectly and the electric brakes on the trailers do most of the stopping.
I never worry about the trailer passing me or pulling me off the road.
Peace of mind, IMHO, is well worth about $100 extra cost, in the long term.
Just my opinion,
Roger

[Aqua Puttana]

Guys,
...
For the poster who's towing "only 3000 lbs." without brakes on the trailer... equally scary, and probably not legal in many states.
...
Just my opinion,
Roger
Roger,
Not to start a debate, but "Probably not legal in some states" is more accurate. Most states use 3000# as the cutoff if they specify a trailer gross weight for required trailer brakes. Another common weight is 1000# or so unladen.

An overview listing is found about 1/2 way down in this link.

http://www.roadkingtrailers.com/MAINTENANCE.htm

FWIW. vic

[sailquik]

Hi Vic,
Hmmmm.... 3 k seems to be the magic number in alot more states than I suspected.
Good Info.
Looks like So. Dakota requires brakes on all trailers..... wonder if when traveling through SD you are OK if brakes are not required in your home state.
I would have thought that the requirements would be around 1,000-1,500 GVW as so many people tow big boats and travel trailers with very small
tow vehicles that do not have anywhere near the brake capacity of a Sprinter.
Ever get to do a "brake check"?
I did a couple in Florida and elsewhere when I had the big truck (6k Mitsubishi-Fuso FG 4X4).
Sometimes you had to actually lock up all the trailer wheels, sometimes the inspector simply went around and listened for the "hummmmm" from
each set of brake magnets.
Don't have to do that anymore as my Sprinter "RV" gives me the priveledge of bypassing all the weigh stations.
3k without brakes, behind a Sprinter Cab/Chasis (overloaded) RV would still be very scary to me.
When I had about 1/2 my braking efficiency (before I added the #10 AWG Blue Wire for te brake magnets) I had to make a couple of fast stops,
and it was not fun. Sprinters big discs did a great job, but with 4k + on the back I was not sure the tail was going to stay behind the dog.
Roger
Roger,
Not to start a debate, but "Probably not legal in some states" is more accurate. Most states use 3000# as the cutoff if they specify a trailer gross weight for required trailer brakes. Another common weight is 1000# or so unladen.

An overview listing is found about 1/2 way down in this link.

http://www.roadkingtrailers.com/MAINTENANCE.htm

FWIW. vic

[Aqua Puttana]

Hi Vic,
...
Looks like So. Dakota requires brakes on all trailers..... wonder if when traveling through SD you are OK if brakes are not required in your home state.

...
Roger
Roger,
Good question. I also noticed that with New Jersey and that is a state I may be towing through. South Dakota is less likely.

My J/22 and trailer is close, but definitely under, 3000# when loaded for regattas. I bought the boat and trailer used. It didn't come with trailer brakes. Casual observation at regattas has J/22 trailers brakes vs no brakes about 50%. So far towing over 10 20 years using full sized vans has not been a problem. Even though I try to look ahead at all times, over the years there have been a few panic stops which worked well. I am now knocking wood furiously.

That said, if I ever need to replace the trailer axle assembly, or get another trailer it will include electric trailer brakes. I do miss having trailer brakes on the icy roads heading south in February. vic

[mrwallysprinter]

Guys,
When talking about trailer wiring in the future, PLEASE specify/differentiate if you are working with an 02-06 T1N or 07-10 NCV3.
Also differentiate if you have a 2500 series Sprinter; 3500 series Sprinter (with dual rear wheels, and much more stable as a tow vehicle); or a RV/MH conversion on a
Sprinter cab/chassis (also with dual wheels.
I see a few photos of 2500 based RVs with 18-20' + travel trailers on the back and
I cringe a bit.
A 2500 based RV has to be running near the GAVW without towing anything. Adding a significant weight trailer looks to me like the tail wagging the dog.
The T1N does not have 6 relays, just one diode block/converter that fits inside the right
rear panel up half way between the bottom of the quarter panel and the RH rear taillight
assembly. (Getting that diode block up through the tight clearnaces is about the most difficult part of an OEM factory towing harness install!)
For the poster who put in a 20- 40 amp circuit breaker..... that's scary! Wonder what else will fry before that breaker trips?
On my '06 3500 T1N installation, the electric brake controller mfg. (Valley Industries)
recommends a 10 amp auto reset breaker @ the tow vehicle battery for the trailer electric brakes and there is no additional breaker needed for the lights with the factory (Dodge/Mopar) trailer 7 way kit.
For the poster who's towing "only 3000 lbs." without brakes on the trailer... equally scary, and probably not legal in many states.
While the factory T1N harness is a pain to install, and for more than one trailer axle needs an additional #10 AWG blue wire to up the current capacity for multi axle trailer brakes, having a bunch of connections to get the "signals" for a modulite system seems to add at least that many places the Sprinter ECM can "sense" electrical plausability issues, which can cause any problem from a simple CEL.... to codes that reset when you restart 3-4 times..... to full blown LHM.
Looks like the NCV3 factory harness is even more of a pain to install (much more complex with all the relays, etc, and apparently several more wire splices to solder).
The T1N factory OEM towing harness could have been "cleaned up" even more with the addition of a "T" connector to plug the Left Rear tail light plug into the towing harness instead of the single SOLDERED wire splice into the wiring for the LH taillight assembly.
Then there would be NO soldering required for the tail/brake/clearance lights.
It would be still better if they included an "T" connector for the blue wire for the electric
brakes that would plug into the harness for the brake switch. Then there would be zero
wire splices in the entire system (unless you wish to add the #10 AWG blue wire for multi axle brakes.
I now have around 25K miles towing 2 trailers (4k-4.5k V Nose Cargo trailer and 25' 4.8k ultra light weight Jay Feather LGT travel trailer) and the lights always work perfectly and the electric brakes on the trailers do most of the stopping.
I never worry about the trailer passing me or pulling me off the road.
Peace of mind, IMHO, is well worth about $100 extra cost, in the long term.
Just my opinion,
Roger

Roger,
I have 2005 158" Dodge Sprinter with factory hitch installation. The lights on the vehicle are all working as they should; however, the towing trailer has recently developed the left turn-brake light always on and the voltage on the trailer hitch jack has a constant 12V on the pin for that light.
I have been reading all the posts in all the different threads and have torn into all the possibilities which have only led to a big time waste of time and frustration.
It seems as if there must be a relay or some device which could be located on the 2005 factory installation towing harness. Do you or anyone else know where this would be?
I'm about to cut the wire going to the hitch and splice into the wire on the vehicle left tail light but it doesn't seem right to "fix" this problem in this manner.
I would like to add that I can not see anyplace where the wire or pin would be obtaining the constant 12V - no smashed wires, no shorted pins, etc.

HELP? COMMENTS?

Thanks,
Frustrated Wally

[mrwallysprinter]

OK, nobody offered any suggestions so I ordered a general service manual which was a waste of money, then I ordered a CD for the 2005 Dodge Sprinter - also a waste of money. :bash:

I had a constant 12V on the factory left turn hitch pin and traced the wire up to the front under the drivers seat. After removing all the relays I could see, I finally removed the entire seat and guess what was under the seat? Part number A0345455032 - it's called the Trailer Control Module - costs about $32 from the dealer.

[sailquik]

Glad you got it fixed!
Interesting, and excellent information.
Did not know that T1N Sprinters had a "Trailer Control Module"
I was under the impression that the Trailer Stability Control module in the
top of the drivers seat box was added to the NCV3 in 2010.
Roger

[mrwallysprinter]

I found a parts site (I think it's in Russia http://partscatalog.ru/mercedes/1/van/903/612/62E/903.612/62E/54/095/p/5) that has part numbers and drawings / diagrams showing the locations which was also helpful. There are also other drawings / diagrams identifying the other relays & control modules which I used to identify the other items under the drivers seat.

[jeffroftn]

my right blinker stays on, after reading all these posts i took the fuse out of the trailer harness beside the battery and all is fixed now. Thank you guys very much!!!
My truck is 06 long and tall 3500 dually
I never did find the relay harness maybe in a different place on mine

[sailquik]

jeffroftn,
Interesting!
As I recall, from installing the entire factory trailer towing harness and a brake controller
in the '06 T1N 3500 I had, there is NO fuse installed by the factory in the factory (avail from
Dodge and Freightliner dealers + MOPAR online) trailer towing harness.
I guess you have something from the after market.
I've been advocating the factory trailer wiring for a long time but have backed off recently.
Perhaps I need to continue to warn people that aftermarket wiring is not usually a good idea
on Sprinters.
Roger

[kendall69]

OK now answer why everyone drives with their turn signal on in Florida?

[PLUMMER]

For what its worth, I found this turn signal thread while searching my own. Luckily mine was much more simple. As it was only a bad connection on the front headlamp assembly connection where the yellow bulb twists in the headlamp unit. still can't figure out why only a 1/64" turn makes it go out to blink fast then blink normal. Unfortunately I tore apart the entire dash searching for a relay that doesn't exist, as the clicking was coming from the instrument pod. And no fuse exists or is listed for turn lamps. My van has the factory tow package and had no relays like pictured here. Thankfully tho that area drain was not plugged and was bone dry. This is for a 2007 2500 170" high top. Thanks

[geochris]

Brian, we were informed by our neighbor last night that one of our tail lights was on. I went to check it out and sure enough the left light was on, so I disconnected the batter, TA DAAA the light and everything else went dark. Connected the battery again and the light came back on, disconnected the battery again and went inside. Today I checked this great site and found your message. Went to our 2007 NCV3, found the 3" plug and pulled the DRIPPING wire harness out. I then found the drain hole and got out of the way of the steady stream of water. I connected the battery again and found one of the relays was warm, not hot AND the light did not come on unless directed by the light switch. Thank you so much for your message!