7 pin connecter on truck

[StanHolder]

Realized my left turn and brake light inop on trailer only. All other lights on truck and trailer work. It appears the pin for the left brake/turn signal on the truck connecter is only showing 3 volts when the brakes are applied, right pin shows 11.88 volts. When I turn on the signal light the voltage changes but never gets above 10 volts. right side gets up to nearly 12 volts. Disconnect brake controller, no help. Swapped 30A fuses, no help. No obvious wire damage under truck. Thought about removing 7 pin connecter and checking for damage/corrosion. No previous history. Any ideas? Thanks

Stan Holder
2006 2500 Cummins
All Stock
200,000 miles

 

[AH64ID]

Is the socket corroded?

 

[StanHolder]

No it's not corroded. I also have a 4 pin connecter wired in from the factory. It also shows only 3 volts on the left side.

 

[Topzide]

Need to check back to the next harness connection. Look for broken/corroded connections. Hope you can find it, good luck.

 

[StanHolder]

The harness connections have no corrosion. Factory installed tow package. Does anyone know where the 7pin/4pin wires are spliced into the wires that run to the back of the truck. I can see several areas that are taped around the black tubing surrounding the wires where they seem to join the main wire bundle.

 

[BigPapa]

 

[seafish]

2006 trucks were the first year that utilized TIPM (Totally integrated Power Module) istead of a PDC (Power Distribution Center) aka normal fuse box.

The TIPM uses IC solid state electronics to control most all of the trucks current distribution and fuse requirements and are particularly susceptible to --

1) voltage and current surges due to bad grounds or poorly installed wire add ons

2) internal corrosion

one of the early modifications people did to these trucks was to add a layer of protection to the TIPM by adding an additional fuse and relay box to bring power fom the TIPM switching functions to the actual trailer plug.

The 3ed gen TIPM IC fuses can be "reset" a limited number of times by a dealer with the proper knowledge and correct version scan tool.

It is also possible to force a "hard reset" on it by properly ad safely disconnecting it from the batteries for approximately 15 minutes. The absence of power makes some of the the TIPM functions reset to factory parameters when power is applied. I do not know if that rest includes the trailer harness functions.

The TIPM can be completely rebuilt , but it is a painstaking and intricate process.

All that said, Dorman manufactures a replacement TIPM that is truck specific for about $450 if you can get one for your trucks specs. That is substantially less expensive them an OEM replacement. I am not sure if it requires a core return.

 

[seafish]

I guess that what I am trying to say with my detailed post above is that your symptoms of no voltage for some trailer light functions at both the 4 pin and the 7 pin plug is likely indicative of a TIPM fault condition and not necessarily that of a simple ground fault.

 

[StanHolder]

Did some more troubleshooting. Getting 3 volt out of the back of the TIPM. Ordered a new TIPM from O'Reilly's, ($670 with a $130 core charge). Now I'm getting 14 volts at the plug. Thanks guys for all the help. I would have never figured that out by myself.

 

[Ozymandias]

Did some more troubleshooting. Getting 3 volt out of the back of the TIPM. Ordered a new TIPM from O'Reilly's, ($670 with a $130 core charge). Now I'm getting 14 volts at the plug. Thanks guys for all the help. I would have never figured that out by myself.

Make sure that your trailers wiring and bulb load is all in top shape or you have a good chance to run into the same problems again.

Like @seafish said, it is all hardwired into the TIPM, no fuses, no second protection, the 2006 was well known for these problems. Later MYs were built better from Dodge but yours is picky for trailer wiring trouble.

 

[Topzide]

Would it be worth putting if some fuse protection between the TIPM and the trailer? I think if my truck, I'd put in a fuse block for all leads on the trailer wiring to help prevent this from happening again! Plenty of water proof fuse blocks out there to mount under truck and spare fuses thrown in truck for that one time you use your buddy's trailer and his has a wiring issue!

 

[GCroyle]

A short reply but didn’t some guys install a series of relays on the trailer to run the lights and the truck only controls the relays? Didn’t Jelag do this ?

 

[Topzide]

If the power consumption is the issue, then yes a relay box with fuses will work. An easier solution might be to install this, Amazon product ASIN B00ASY29AW.
Did this on my 01 1500 and works great. Different manufacture though. Hope this helps.