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hemsteadc

lost all trailer power - SOLVED

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2008 M2-106 Sportchassis.

I have lost all my trailer lights - brakes, turn, marker.  

To start troubleshooting, I turned on the left blinker, and with a voltmeter checked each pin on the truck socket, but I saw no voltage on any pin.  It seems unlikely that all the fuses and breakers would blow at once.  I also don't understand why there are fuses and breakers - 2 types of breakers.

My next step would be to pull the socket from the rear of the truck and see if any wires have come loose - thinking maybe the ground wire.

I will definitely apply 12v to the trailer socket to verify it's in working order.    

Anybody know what is a common cause of failure of this system on the truck?  Can you point me to things to check?

Edited by hemsteadc

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95% of all electrical problems are bad ground. Since that is the one thing in common to all your lights taking a dump, I'd start there at the plug. (Usually the center pin)

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Also the there is a fuse panel located inside the rear drivers side on the right. I don't where the ground originates but I would be  suspect a ground.

Clay 2015 Sports Chassis

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"... it would most likely be one of two different things. 1. The fuse/relay box in the drivers side storage box on the bed either has moisture in it or has a fuse/relay blown. 2. There are either 2 or 3 in line fuse/relay’s on top of the battery. One of those might be blown. You will have to take them out to check them."

This is what Sportchassis said. Jees... how many fuses does this thing have??

Edited by hemsteadc

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look behind the rear bench seat on the driver side.  there should be a relay block there, make sure it has power.  it contains relays and fuses.  it is supplied with 12v full time from the battery directly.

if all that works, then move to the unit under the truck.  FL M2-106 has lots of fuse boxes all over the place and its all computer controlled.

The rv trailer plug is the only thing not computer controlled and directly feed by the battery.

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I have asked for a Block diagram  for electrical and air delivery, once or twice showing location and purpose. Digging around while cleaning, can leave questions.

It seems the truck is just like a RV, one person has done all the wiring for 19-20 years.

When I bought my Sport Chassis used it had two electrical problems. The BU camera wouldn't work for reverse. (Bad diode under dash). The rear seat A/C put out hot air. (a miss wire to rear A/C switch in dash, solution was to turn coolant valves to heaters off under hood until fixed). Clay

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i have wiring diagrams for the wiring SC installs which is minimal .....  i also know the routing locations that i should document on of these days.  Should post them for SC owners to have here ....

SC installs the rear AC up until a while ago, now Freightliner installs it the factory and all setup.

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Found the copies of the wiring diagrams that SC installs in the M2-106 ...  Drop me a message if you need a copy.

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3 hours ago, Pug said:

The rv trailer plug is the only thing not computer controlled and directly feed by the battery.

I'm hoping to pull out that socket and find a dangling ground wire.  But that would be too easy.

Edit: That ain't happening.  The wires are in a conduit and that socket isn't coming out.  The good news is I found a blown 30a fuse in the fuse panel, located in the storage compartment on the driver's side. It's a good thing I have a friend at Sportchassis who can tell me exactly what's where on THIS truck.

Edited by hemsteadc

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I have the 2009 M2. Between the frame rails behind the cab there is a collection of modules. J1939 communication protocol (I think) one of them is the lighting module. On my truck one of the turn/brake lights quit first then the other. I rewired to the truck lights. Last year it started doing REALY crazy things! The trans didn't want to shift until at hit 2k RPM. then hard. speedo would quit along with tach, then start working. When not working hit the left turn signal the speedo would work.

I have a scan tool that will scan these trucks, it it said the J1939 was the issues. I tried several local HDT shops they had no clue. One said a ground issue. Nope. Wound up taking it to freightliner. I had a bad connector that let water in and shorted out the module. If I remember correct it was about $1200 fix. Hope you catch it before I did and its a cheeper fix.

Good luck, Wayne

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trailerlights.jpg

Fuse box located in storage compartment on driver's side.

1. 'Trailer Ignition' relay.  It tested fine.  I've sent email to SC asking what that means, but meanwhile, let me guess.  When the trailer is plugged in, that relay closes and provides power to the truck socket.  Therefore,  I must plug in the trailer umbilical to test. No?

2.  30 fuse, labeled 'Trail Ign.'  It was blown. 

 

 

 

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Crap.. replaced the fuse and still not working.  That's not fair!  Mfr said there are fuses on the battery, I'll look there next.  Man if I can't fix this it's going to be expensive, and it's really not smart to be driving sans trailer lights.

Edit: applied 12v to trailer plug.  Running lights work fine.  Problem  not there.

Edited by hemsteadc

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batterytop.jpg

 

Sportchassis was right on!  Shown above is the top of the battery, and 4 fuses mounted with bolts.  The indicated one is blown.  It tested as an open circuit, so I put a jumper across it and bingo!  Got 12v at the socket instead of 0.5v.

I'll have SC send me a couple new ones.  Now I wonder why these fuses blew? 

Perhaps this will help someone else out someday. I was NOT looking forward to another expensive and time-consuming trip to the service center.

 

 

 

 

 

 

 

 

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Looks like not all SC trucks are setup the same and even in the same year model there seems to be differences ....  What a pain.   Glad you found it !  I would care spares to be on the safe side.

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6 hours ago, Pug said:

Looks like not all SC trucks are setup the same and even in the same year model there seems to be differences ..

   True.  And the manual is generic like RVs.  This saved me a tremendous amount of time, stress, and money.

I thought this would be some kind of specialty fuse sent from them, but he said just get thee to any auto parts store.

Edited by hemsteadc

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