schubi_F150

Hi,

could anybody explain me how the wiring for the tow-coupling is performed.

I have the problem that my trailer which is equipped with an hydraulic unit powered by a separte battery is not charging during driving.

I found in the fuse box a relay "R05 - Trailer tow battery charge", but there is no relay on the socket.

As I can see the original wiring-socket (color blue) is unplugged next to the rear bumper.

It seems that there is a new wiring, maybe it was necessary for Germany.

I would be verry thankful if sombody could tell me how the realay R05 works and which pins in the input jack are for charging a battery on the trailer.

I hope you could understand me.

It is verry difficult to find information for US-cars in Germany.


Best greetings from Germany, Munich

Juergen

rtg143

There's power at pin 30 from the battery (fuse 106), pin 85 goes to the blue wire in the rear, ignition power (fuse 13) goes to pin86 and 85 is to ground.

lasttruck

Good morning. Was stationed in Munich at Mcgraw Kaserne from 1982 to 85.

The fuse box relay allows for charging of the trailers battery while the ignition is on. When the ignition key is off, flow to the trailer battery is disconnected via the relay so that the trucks battery is not drawn down.

schubi_F150

Thanks Bert, Thanks Jim,

for your fast reply and helpfull information. Sorry, I still have three problems:

1. Where could I buy such an relay, because there is not any in the socket (fuse box)
2. Which cables from the original cable harness (color of the single cables) I have to put additional to the power outlet next to the tow-bar. (I took some pictures of the two unpluged connectors in the rear). As I understood, I need ground and power from the relay.
3. What is the small conector with the four cables.

Best regars

Juergen

schubi_F150

Sorry, I forgot to add the pics.

rtg143

The small connector is for towing small trailers and it hooks directly to the trailer. The other one is supposed to be connected to the trailer plug. Did you just disconnect it to show it? Either way, the orange wire is the power wire from the relay.

schubi_F150

Thanks Bert,

Both connectors are disconnected under the rear bumper, because there is a new cable harness applyed, which is connected to the power outlet (German version) of the tow-bar.

The only thing I have to do is to connect the orange cable and a ground cable (color?) with the designated pins of my outlet. Furthermore I need the correct relay. Is that right?

Thanks for helping me.

Regars,

Juergen

rtg143

The ground wire is white. The relay is a standard Bosch relay.

schubi_F150

I found the relay information in an internet shop (I need Type B), but there are several wiring diagrams S1-S6. Could sombody tell me which relay I need.

Best regards,

Juergen

Mod (Ret.)

I'd contact your nearest Ford dealer and ask the parts department folks. You don't have to buy their relay (most likey more expensive than an electronics shop like Fry's).
From your pic, I'm confused, as both those relays are the same, and the truck should be pre-wired at the fuse box for the correct "switch". Your diagram is showing how many ways a relay can be triggered. The Ford factory wiring is already in place. Just plug in the relay.