2nd Gen Non-Engine/Transmission abs and brake lights on and no speedo after plugging in trailer lights

[TComparetta]

HELP !! I bought a used trailer hooked it up and on the way home I now got an abs and brake light on and no speedo until i reach about 40mph. all was fine till I hooked up the trailer. any one ever had this happen ? Any suggestions on how to figure out why this happend and how I can fix it would be very much appreciated. . I am 1500 miles from home and worried to drive it like that. I have a 99 dodge ram 2500 4x4. thanks

 

[DMather]

Obvious questions first...
if you unplug the trailer, do the abs and brake light go off and the speedo work?
Have you checked fuses?

 

[TComparetta]

the fuses are the first thing i thought of, they all looked ok, then I unplugged and took for a ride to the store and all is the same lights on and no speedo, thanks

 

[DMather]

The only thing that make sense to me is the speedo sensor has gone bad. (speedo sensor may be used as part of the ABS as well and that would make the connection between the two systems. )

 

[Allnew2Me]

The rear ABS tone-ring in the differential also supplies the signal for the vehicle speedo.

If all this fun occured when you plugged in the trailer the first thing I would check is the male trailer plug. It may not be wired to the standard of the truck female connector, causng crossed wires.

 

[TComparetta]

thanks, it most likely was the trailer wiring, as upon closer looking was a cob job. I am now looking at the spped sensor on the rear end, does anyone know how to ohms test the sensor with out jacking up the truck. I am disabled and my wife has to do most of the stuff, so I was looking for an easier way, not to mention I am a long way from home and only have limited tools with me. I still wonder why the wiring in the trailer took out the sensor and didnt blow a fuse first. . the thing is every thing works on the truck and trailer, but the dreaded abs and brake lights are on and the no speedo till it hits 35 or 40 mph on the truck. never a dull moment. .

 

[DavidC]

The rear speed sensor should ohm around 1800. Now the rest of the story. I had the same symptoms, lights on no speedo till 40mph. This happened after washing the truck. When I would shut the truck off and restart everything was fine till 40 mph then the lights came on and no speedo till 40 mph or a restart. I took the wire harness off at the trailer plug, dried and cleaned then filled with dielectric grease. Reassembled never another problem.



Dave

 

[TComparetta]

thanks, i am going to do the wiring plug as suggested, but does anyone know where all the disconnects are on the trailer harness from the factory. I know the obvious but is there any under the truck along the frame, I want to get to all the connections to check them. I have the 99 dodge 2500 with the quad cab and 8 ft bed

 

[DavidC]

Don't take this as gospel but I think when I was running down the harness there were some plugs near the bottom of the front Drivers wheel well.



Dave

 

[SDrake]

The rear speed sensor should ohm around 1800. Now the rest of the story. I had the same symptoms, lights on no speedo till 40mph. This happened after washing the truck. When I would shut the truck off and restart everything was fine till 40 mph then the lights came on and no speedo till 40 mph or a restart. I took the wire harness off at the trailer plug, dried and cleaned then filled with dielectric grease. Reassembled never another problem.



Dave

If I hadn't gone through a lot of wierdness experienced with my speedometer i would have been thinking "You gotta be kiddin. " I had other problems with my speedo that coincided with the coming and going of my temp reading in the overhead console. My biggest problem has been solved with the discovery of a bad 14 pin connector on the ABC control module. Had the module rebuilt, replaced the connector and speedometer does not do the wierd things like move up and down while sitting still and just dead for days on end and it has been working perfectly for a couple of weeks now. But while all that wierdness was going on one day before the speedometer went completely wierd i went through a carwash and the speedometer was instantly dead and stayed dead for about two weeks during cold weater, then it came alive one day but with some wierdness.



I said all that to say this. I am am not confident that my troubles are over because the ABS controller problem does not explain what happened when I went through the car wash unless the car wash behavior was just a coincidence. I am still agast at the thought that a wet or shorted trailer plug could affect the speedometer but no longer discounting it. You better believe that if I go through a carwash again and the speedo quits i will be at those connectors.

 

[SDrake]

The rear speed sensor should ohm around 1800. Now the rest of the story. I had the same symptoms, lights on no speedo till 40mph. This happened after washing the truck. When I would shut the truck off and restart everything was fine till 40 mph then the lights came on and no speedo till 40 mph or a restart. I took the wire harness off at the trailer plug, dried and cleaned then filled with dielectric grease. Reassembled never another problem.



Dave

If I hadn't gone through a lot of wierdness experienced with my speedometer i would have been thinking "You gotta be kiddin. " I had other problems with my speedo that coincided with the coming and going of my temp reading in the overhead console. My biggest problem has been solved with the discovery of a bad 14 pin connector on the ABC control module. Had the module rebuilt, replaced the connector and speedometer does not do the wierd things like move up and down while sitting still and just dead for days on end and it has been working perfectly for a couple of weeks now. But while all that wierdness was going on one day before the speedometer went completely wierd i went through a carwash and the speedometer was instantly dead and stayed dead for about two weeks during cold weater, then it came alive one day but with some wierdness.



I said all that to say this. I am am not confident that my troubles are over because the ABS controller problem does not explain what happened when I went through the car wash unless the car wash behavior was just a coincidence. I am still agast at the thought that a wet or shorted trailer plug could affect the speedometer but no longer discounting it. You better believe that if I go through a carwash again and the speedo quits i will be at those connectors.

 

[TComparetta]

thanks found the other connectors, all the connections to the trailer harness looks good, all is still the same, working on some of the other suggestions, any other ideas please let me know. . thanks

 

[TComparetta]

Thanks to all who helped, It was the rear speed sensor. . speedo back and all lights are off. .