I was going to install something at the rear of the van, and the trailer electrical connector, 7-pin, indicated a + that I understood to be hot for charging trailer batteries (I need ignition on/hot). But when I tested it was dead.

So I checked the fuse box and power distribution box. Everything's there BUT a relay at position E for "Trailer Battery Charge." All the lights and stuff worked back there for 4 pin connections, which is all I've ever used. I've got the "Trailer Battery Charge Relay, Modified Vehicles" in position 22, but it seems to be a fuse position, so I'm kinda unsure of where it fits in. There's also a 5A fuse in the driver's compartment fuse box at 15 for "Trailer Battery Charge Relay." So I'm guessing these both (15 and 22 in the PD box) are for the missing relay. I hope.

I've seen aftermarket kits for Ford that included the receptacle and various fuses and relay, but couldn't determine the relay specs. Not sure if it's the same as some others there (P6STD F0AB-14B192-AA). I'd like to know the part no or other identifying info for this so I can try slamming one in and seeing if I can get the power to work.

And BTW, does this produce ignition on power, or always on power?

Position E is top left in the row of black relays on the right of the photo.

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2001 Ford E250 Sportsmobile with Salem-Kroger 4x4 conversion

rob: Any chance you could put the year, make and model and engine type of your van in your signature. I have the E-Series Wiring Diagram shop manual for the 2002.

You may want to take one of those other relays and put it in the trailer relay terminal and recheck if you have hot at the trailer tow plug.

Attached Files

Trailer Battery Charging Diagram.pdf (35.5 KB, 19 views)

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2002 E350 ext.; 160K; 7.3L; 4R100 (w/4x4 deep pan & filter); 4x4 conv. w/2007 F250/F350 coil frnt axle (oppos. dual Bilstein press. shocks cured DW) diff chg from 3.55 to 3.73 (bad!); BW1356 t.c. (bad!); LT265/70R17/E Michelin LTX M/S2; Engel MT60 Combi Fridge-Freezer; 4 BP 380J pv panels; Auragen 5kw AC gen. in top alt. position; Webasto Dual-Top; Voyager top. 1995 5.8L EB Bronco, bone stock.

It's a 2001 E250 Ford 5.4L

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2001 Ford E250 Sportsmobile with Salem-Kroger 4x4 conversion

Sorry...can't quite decipher the diagram. It's also a bit different than ones I've seen online.

Thanks.

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2001 Ford E250 Sportsmobile with Salem-Kroger 4x4 conversion

If you look in the center of the page you will see the relay. It is normally open (i.e., off) so you should be able to jump terminal 30 to 87 and get hot at the plug receptacle by jumping. but bottom line is that you won't get it to work "automatically" without the PCM or other controller (brain) sending low voltage current at appropriate times to the relay. Since the PCM or other controller must necessarily have a regulator built into it to prevent trailer battery overcharging, I would think that you would want to install that relay rather than just jumping the relay terminal.

What happens when you pull one of the adjacent relays and put it in that spot? Or just go to the Ford dealership and buy one or two relays and stick one in the appropriate terminal and see what happens. Please post your results.

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2002 E350 ext.; 160K; 7.3L; 4R100 (w/4x4 deep pan & filter); 4x4 conv. w/2007 F250/F350 coil frnt axle (oppos. dual Bilstein press. shocks cured DW) diff chg from 3.55 to 3.73 (bad!); BW1356 t.c. (bad!); LT265/70R17/E Michelin LTX M/S2; Engel MT60 Combi Fridge-Freezer; 4 BP 380J pv panels; Auragen 5kw AC gen. in top alt. position; Webasto Dual-Top; Voyager top. 1995 5.8L EB Bronco, bone stock.

Its just a regular relay, like you would get with a fig light kit. You can borrow the fuel pump relay to test it. (on conversely, borrow the trailer charge relay if the fuel pump relay ever goes out).

I have noticed that the cheap no-name relays really don't live as long as an OEM relay. BTW - It doesn't even matter what car you pull it from. Toyotas, Nissans and many others all use that same relay (Chrysler uses the same shape relay for their fuel pumps, but it actually switches between the two outputs).

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2000 E450 dually V10 wagon

On my. 2009 van the relay is on with ignition. Voltage is controlled by the alternator.

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2009 E250 RB 5.4L "SilVan"

One feature of the factory trailer charge relay is it only turns on after the starting battery reaches a certain charge when the engine is running, so that way it gets all the charge first if its low.

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2000 E450 dually V10 wagon

It is the same relay as used in the other positions. I finally found the diagram for my trailer kit; evidently years and years ago SMB didn't put in the relay after installation, but they did give me the diagram (they left out a fuse or two as well; I suspect they pulled 'em for electrical work). It's a f0ab-14192-aa.

To find one (it's tough to find via part no. f0ab-14192-aa) just look for a blower motor one. Makes the socket at the rear hot with alternator voltage, which is pretty high, 14+ on my van when started up. Might fry what I intend to put there; we'll see.

EDIT: I'm trying to install a remote backup camera system and it did NOT fry. Yippee! I could've used another circuit but I figured what the heck, might as well have it always on.

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2001 Ford E250 Sportsmobile with Salem-Kroger 4x4 conversion

Rob: Admittedly, I don't know what I am talking about, but consider this. And if we are lucky more knowledgeable people will chime in.

I think it would be better to fuse and run an ignition-controlled hot wire to the rear to your backup camera than to hook up your backup camera to a PCM-controlled relayed-trailer-battery-charge wire. Why?

Well the PCM which controls a battery charge function must by nature control the charge current so as to not overcharge the trailer battery.

Because I will bet you dollars to donuts that the trailer battery charge relay is a switch, which is switched on and off by the PCM.

How does the PCM know when to turn the switch on and when to turn the switch off?

To know, the PCM has to get an electrical signal from somewhere.

And because electrical resources in a 12v battery powered vehicle are, by nature, limited.

When it gets the signal that the trailer battery needs charging, the PCM may be turning off other stuff to charge your trailer battery.

Or the PCM may consider the constant load from your backup camera which is now hooked up to your trailer battery charge relay to run the alternator more than necessary.

Or to diminish alternator charging to your starting battery to divert it to your trailer battery which is now your backup camera.

I don't know, but it doesn't seem right to use a PCM controlled relay as a constant hot for your backup camera.

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2002 E350 ext.; 160K; 7.3L; 4R100 (w/4x4 deep pan & filter); 4x4 conv. w/2007 F250/F350 coil frnt axle (oppos. dual Bilstein press. shocks cured DW) diff chg from 3.55 to 3.73 (bad!); BW1356 t.c. (bad!); LT265/70R17/E Michelin LTX M/S2; Engel MT60 Combi Fridge-Freezer; 4 BP 380J pv panels; Auragen 5kw AC gen. in top alt. position; Webasto Dual-Top; Voyager top. 1995 5.8L EB Bronco, bone stock.