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Hello everyone,
Having issues with my 7-way trailer socket. that was equipped with by Ford when purchased Van. My left turn/stop and right turn/stop both read slightly under 12 volts when truck is running but voltage drops below 6 volts with any load, it barely illuminates a single led light.
I traced to a plug underneath by spare tire that feeds the trailer socket and get same readings. This tells me problem is farther forward towards engine. The fuse is good, and I replaced the Tow left and Tow right relays under hood, but problem remains. Could anyone suggest where/what to check from here? Possibly find a electrical diagram to help trace this yellow and green wire? I would appreciate any help and suggestions,
There is a lot of wire and at least one connector between the fuse box and trailer plug. Something is corroded, pinched or damaged. Rig a 12v bulb with wires ( I use a 35w halogen bulb with a built in power wire) and test it at various points in the wiring run (fuse, connector under the van etc).
Or trace the wire run and find and clean every connector.
There is a lot of wire and at least one connector between the fuse box and trailer plug. Something is corroded, pinched or damaged. Rig a 12v bulb with wires ( I use a 35w halogen bulb with a built in power wire) and test it at various points in the wiring run (fuse, connector under the van etc).
Or trace the wire run and find and clean every connector.
Hi Don, thank you so much for your reply and input. After research I learned the 2006 E series has a 20A fuse for the "Trailer tow turn signals" in the Power distribution box under the hood, it also has separate relays for trailer left turn and trailer right turn under hood, this leads me to assume there is 2 wires from this point. Since both the left and right are giving me the same trouble/readings I'm guessing/hoping the trouble is under the hood and can eliminate a lot of tracing in plastic tubing and harnesses. I plan on going back at this tomorrow and certainly will report my findings.
I think you better swap those relays with new or good used ones (for a test) before getting too involved with the wiring.
Substitute regular bulbs for your LEDs in case there is not enough voltage drop to make the relays function as designed.
Check the grounds in that circuit. 101 102 401 202 203 (check them all if you can)
Thanks so much for all the help.... problem is solved.
After logically thinking the problem has to be before the left and right relays since both had same problem, this morning went straight to the Power distribution box under hood to read voltage at the "Trailer tow turn signals" fuse and was blinking red in sync with dimly lit led light I temped out for testing.
My problem originally started when I plugged in a trailer that's been sitting and had a short, it blew this fuse. When I went to parts store for a new fuse all that was available was these fuses that lit red when blown. Testing 1 side of fuse had 12 volts the other 4-5 volts. Pulled the fuse and was clearly blown, I must have blown it again in my trouble shooting for trailer. Replaced with a standard 20A fuse and everything worked as it should.
Don't know if this fuse was defective but it definitely was allowing volts across even when blown. I will certainly stay away from this type.
The indicating fuse was not defective. The way they work is the indicator is connected across the fuse terminals. So long as the fuse is good, nearly all of the current flows through the fuse link leaving none to light the indicator. When the fuse is blown, all current flows through the indicator. The indicator provides enough resistance that, even if the protected circuit is shorted the current flow is so low that nothing will be damaged. If the circuit is open (i.e., there is no load) then there will be no path for the current to flow and the indicator will not light even if the fuse is blown.
When testing the circuit with the fuse blown, the test device and the indicator are in series so the voltage is divided between them resulting in the low voltage readings you saw.
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