Community Forums

vincej1657 · 08-21-2016, 05:41 PM

I have a 1996 30' Travelaire C class on a Ford Econoline 350.

All of a sudden out of nowhere I have several electrical failures on the running lights, brake lights, and the reverse lights. I have checked the power box and the fuse box. Fuses are all good. So I am guessing that I have a bad ground, or alternatively the wiring harness serving the lights at the rear of the rig has come loose.

All electrical cabling for the rear lights appears to pass through the cabin wall up to the truck. But I can't identify the cabling as it enters the engine compartment.

So, assuming the truck delivers the current, and the lights 25' to the back, what is the best way of diagnosing my problem and testing the ground?

Many Thanks !

BFlinn181 · 08-21-2016, 06:30 PM

You could use a cable tracker. It generates a signal in the wire you want to trace, then a probe detects the signal in the wire without having to cut through insulation. I use one to find many circuits in my RV that are giving me trouble.

Kiawah · 08-23-2016, 07:12 AM

To check for a bad ground, use a volt meter and after pulling a bulb, check the voltage by proving the positive of the bulb socket, with the other Meyer lead on a good ground. Use a piece of wire back to the battery negative post if need be. Compare that to the reading you get with the negative probe on bulb socket. If different, you have a ground problem.

dpinvidic · 08-23-2016, 07:25 AM

Start at your trailer connector.
use a test light to confirm each wire has 12v when that wire is active.
Do this with the test light connected to chassis ground.

Then connect the test light between a active wire (brake light pin) and the
ground pin of the connector.

You can also measure the resistance betwen the ground pin and chassis ground, should be less than 1 ohm.

Regards,

Dan

nothermark · 08-23-2016, 07:25 AM

One of your best tools for problems like that is a 30 ft or so clip lead you make yourself out of any flexible wire and a couple of alligator clips. It can be a meter return looking for voltage drops to ground. Small wire is fine since the current is negligible.

You might find something useful on this site:

https://www.fleet.ford.com/truckbbas.../techspec.html

It might stop at 2000 but that might be close enough for your chassis. They do not change much for years at a time. On our 2012 chassis the harness for the lights is connected to the Ford wiring about at the gas tank along the inside of the left frame rail. If the plug/socket is getting corroded that could give you similar problems. You probably have something similar.