Tailer Turn Signal not working, ? Where is the trouble

[brillmtb]

My Right trailer blinker stopped working, running light OK. Bulb ok. I checked the 7-plug at the truck and the pin at 3 O clock is not cycling off/on. So two questions came up.



1. Is there a separate relay for the trailer as the truck right rear is flashing

2. Is it practical totrace the break in this wire if the answer to 1. is NO or just pull and replace the harness for $89.

 

[ScottLewis]

On the '06, failure of the right turn signal usually indicates a TIPM problem that requires dealer involvement. Don't know if the '03 is the same though. Do a search on TIPM and read up.

 

[Prairie Dog]

He looks to have an 03 so no TIPM. You have a good old fashioned fuse and hopefully thats all it is.
Check the fuse center under the hood.

 

[brillmtb]

I should have added that the fuse was good

 

[Motorhead]

Check at the BACK of the 7 pin plug and make and break a few times the connection where the wire loom plugs into the back of the plug. I had a bad ground once in my '07.

 

[brillmtb]

I just noticed in the shop manual that there is a separate right/left trailer turn signal relays. I wonder if they are the ones in the fuse box

 

[jelag]

There is a left and right turn signal fuse for the trailer. . make sure you've checked both. . If you pull any of the connectors apart and put them back together... make sure you put some Vaseline or other product to keep the pins water tight...

 

[brillmtb]

Can't find the relays

 

[DZink24]

your 03 is the same as my 04. (no TIPM) unfortunately, it is in the FCM, and it is not an inexpensive fix. i had the same exact light issue as you several years ago, the dealer and i split the difference because the warranty co. wouldn't cover it, and a year later the trailer brakes went the way of the turn signal. i had an independent trailer dealer hot wire the trailer brakes up for me. then i got to have running lights 4 times before they quit working as well. . dealer wants 1,200 to fix the running lights. i'm good, i just won't tow a trailer at night. . every time something gets fixed, another light decides to quit working.

 

[Missouri Mule]

brillmtb, is the bulb for parking/running,turn signal and brake lights ? If so is the brake light working. If not you probably burned out turn signal/brake filament.



Brake/turn signal light get used more often than parkng/running lights.

 

[TCDiesel]

This may be the cause. replace fuse #47 with 10amp and this will never happen again,leave 15amp in #47 and you will burn another circuit board.

 

[Bill Stockard]

This may be the cause. replace fuse #47 with 10amp and this will never happen again,leave 15amp in #47 and you will burn another circuit board.

Thanks for the tip. I'll be replacing the 15-amp fuses with 10-amp fuses today. I don't need that problem!



I looked up the price online of a FCM which was about $80 and a replacement IPM base was just a bit less than $400. (If I found the correct part numbers. )



Bill

 

[brillmtb]

Bulb and fuses fine. Tested power at truck plug and no cycling of off and on to right trailer signal so wires and bulb going back likely ok as we'll



Autozone showed a separate order able part for the relays but no availability. Don't know if that means you have to replace the whole FCM or just the relay. I think my fuses were already 10 amp but will go down if not. May go to7. 5 if 10 as I would rather blow a fuse.

 

[brillmtb]

Reading a bit more. Some sites reporting that in the 2003 the relay is integrated with the fuse box and the whole fuse box needs replacing. Is this where theFCM is located?

 

[jhenderson]

Attached to the fuse box, between the box and the fender.

 

[TCDiesel]

The FCM is bolted to the PDC. I have Never replaced the FCM for any type of trailer wiring or fail power to towed units 03-05.

 

[brillmtb]

TCDiesel

Can you elaborate? Are you saying you have fixed problems like this by replacing the PDC in this yr truck. I thought the relays were physically located in the FCM and another site reported having to replace the firebox which makes no sense

 

[bsappington]

I had the same thing happen to me. one of the turn siganl/brake lights on the trailer quit working.



There are several ways to deal with this. the easiest is to install one of those boxes that converts your seperate barke and turn signal from the tail lights on the truck and wire it to the 7-pin.



On my truck we disassembled the PDM and changed the relays inside with newer, better relays. I haven't had a problem since. However, i have tried this on 2 other truck and it didn't work. In those cases we believe the FCM had to be changed. It is the FCM that give the signal to the relay on the ground. Unfortunately I have not come up with a good way to figure what is causing the problem. if you can hear the relays clicking with the engine off then most likely the relays are the problem.



Diesel Outfitters in Arlington, Wa. (I work there part time) can replace the relays for you. We have a spare box but i found out that the plugs are different on the bottom from year to year. The best would be for you to send the box in, we can change the relays and send it back.



PM me if you are interested in getting the relays changed.

 

[TCDiesel]

WOW... The FCM is mounted to the PDC. . it absolutely has NOTHING to do with the turn signals on 03-04 tow, if you burn the circuit how can relays fix it. Re-wiring to the power unit is NOT an option I would explore Unless you wired it separately like other have done.

 

[TCDiesel]

Front control module FCM 03/05