Big Blue's Transformation

[kramttocs]

I substituted a Bronco relay box in place of the trailer relay box giving me 4 relays instead of just 2. I went into the underhood fuse box (PDC) and cut the wires feeding the two trailer signal light relays (fuses 6 and 7) and ran them out to a small 4 pin male/female plug set. From there the wires were run to pin 85 or 86 of a pair of Bosch relays, the other side 86 or 85 was connected to ground. Pin 30 of these was connected to the existing battery feed for the factory 2 relays and pin 87 was connected back through the plug to the PDC and then to fuses 6 and 7 to go to the trailer plug in the back bumper.

I will try to get some pictures of the box I used and how to get the terminals out of it or insert new ones in it. I transferred the original trailer relay wiring into the Bronco relay box.

So in yours (and later years?) the trailer turn signals are also on a separate load circuit from the truck signals?

Edit: just saw the diagram on the previous page showing this so I'd missed the inclusion of turn signals into the backup lamp discussion

[Gary Lewis]

I substituted a Bronco relay box in place of the trailer relay box giving me 4 relays instead of just 2. I went into the underhood fuse box (PDC) and cut the wires feeding the two trailer signal light relays (fuses 6 and 7) and ran them out to a small 4 pin male/female plug set. From there the wires were run to pin 85 or 86 of a pair of Bosch relays, the other side 86 or 85 was connected to ground. Pin 30 of these was connected to the existing battery feed for the factory 2 relays and pin 87 was connected back through the plug to the PDC and then to fuses 6 and 7 to go to the trailer plug in the back bumper.

I will try to get some pictures of the box I used and how to get the terminals out of it or insert new ones in it. I transferred the original trailer relay wiring into the Bronco relay box.

Thanks, Bill. And maybe your pics will show how it mounts. As said in the email, the EFI air box bracket has a spot on the side of it to mount a hood labeled Trailer Relays. I don't remember how many relays snap into it, but I'm guessing two.

[Gary Lewis]

Thanks, Bill. And maybe your pics will show how it mounts. As said in the email, the EFI air box bracket has a spot on the side of it to mount a hood labeled Trailer Relays. I don't remember how many relays snap into it, but I'm guessing two.

Actually, it appears to hold three relays as it is marked Trailer Tow, Fuel Pump, & EEC Power. That means that the PDB I have is apparently not wired for the fuel pump nor EEC power relays.

[85lebaront2]

Actually, it appears to hold three relays as it is marked Trailer Tow, Fuel Pump, & EEC Power. That means that the PDB I have is apparently not wired for the fuel pump nor EEC power relays.

Gary, the 1988-91 trucks had the EEC and Fuel pump relays on the back of the air cleaner mount, the 1996 PDC I have has the relays mounted on the back side of it. Note relay box under the cruise control motor housing. Green fuse was pulled to do a "hard reset" on the EEC after flashing it in place.

[Gary Lewis]

Gary, the 1988-91 trucks had the EEC and Fuel pump relays on the back of the air cleaner mount, the 1996 PDC I have has the relays mounted on the back side of it. Note relay box under the cruise control motor housing. Green fuse was pulled to do a "hard reset" on the EEC after flashing it in place.

Bill - Good to know. I have a '96 PDB. Thanks.

[85lebaront2]

Gary, the 1988-91 trucks had the EEC and Fuel pump relays on the back of the air cleaner mount, the 1996 PDC I have has the relays mounted on the back side of it. Note relay box under the cruise control motor housing. Green fuse was pulled to do a "hard reset" on the EEC after flashing it in place.

Ok, here are 3 pictures of my PDC labeled, unfortunately due to the size of the pictures the labels are hard to read in some areas. First is all the fuses down the front side, second is the fuses down the center, third is the relays. You will notice some open slots in the fuses and one open relay location. The connectors can be removed from a damaged PDC (doesn't have to be a truck one and could even be from a non-Ford product). Fuses are numbered in the owner's manual as follows, front row fender in, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Center row, fender in 13, 14, 15, 16, 17, 18, 19, 20, 21, 22. Relays are numbered same way, fender in, 1, 2, 3, 4, 5.

There is no fuse in slot 8 on a gas engine, none in slot 2 unless it is an ambulance with 200 amp alternator or has fog lights. Slot 11 is empty, along with 14, either or both could be added if needed. If the donor truck did not have a trailer tow package then fuse slots 6, 7, 18 & 21 will not be used (and will not have either or both connectors) and relay 4 will not be there.

[85lebaront2]

Gary, the 1988-91 trucks had the EEC and Fuel pump relays on the back of the air cleaner mount, the 1996 PDC I have has the relays mounted on the back side of it. Note relay box under the cruise control motor housing. Green fuse was pulled to do a "hard reset" on the EEC after flashing it in place.

Ok, here are 3 pictures of my PDC labeled, unfortunately due to the size of the pictures the labels are hard to read in some areas. First is all the fuses down the front side, second is the fuses down the center, third is the relays. You will notice some open slots in the fuses and one open relay location. The connectors can be removed from a damaged PDC (doesn't have to be a truck one and could even be from a non-Ford product). Fuses are numbered in the owner's manual as follows, front row fender in, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Center row, fender in 13, 14, 15, 16, 17, 18, 19, 20, 21, 22. Relays are numbered same way, fender in, 1, 2, 3, 4, 5.

There is no fuse in slot 8 on a gas engine, none in slot 2 unless it is an ambulance with 200 amp alternator or has fog lights. Slot 11 is empty, along with 14, either or both could be added if needed. If the donor truck did not have a trailer tow package then fuse slots 6, 7, 18 & 21 will not be used (and will not have either or both connectors) and relay 4 will not be there.

[Gary Lewis]

Ok, here are 3 pictures of my PDC labeled, unfortunately due to the size of the pictures the labels are hard to read in some areas. First is all the fuses down the front side, second is the fuses down the center, third is the relays. You will notice some open slots in the fuses and one open relay location. The connectors can be removed from a damaged PDC (doesn't have to be a truck one and could even be from a non-Ford product). Fuses are numbered in the owner's manual as follows, front row fender in, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Center row, fender in 13, 14, 15, 16, 17, 18, 19, 20, 21, 22. Relays are numbered same way, fender in, 1, 2, 3, 4, 5.

There is no fuse in slot 8 on a gas engine, none in slot 2 unless it is an ambulance with 200 amp alternator or has fog lights. Slot 11 is empty, along with 14, either or both could be added if needed. If the donor truck did not have a trailer tow package then fuse slots 6, 7, 18 & 21 will not be used (and will not have either or both connectors) and relay 4 will not be there.

Thanks, Bill. That helps.

So the '96 PDB will have the PCM and fuel pump relays.

But I'm confused about what relays I have on the firewall right now. I've been saying there is a "trailer relay" but from my run through the '85 EVTM just now I don't see one. Instead the brake, turn signal, and backup lights run off of the same wiring that the truck's lights do. And the only relay I find associated with "trailer" is the aux battery relay that ensures when the engine is off a trailer or camper can only drain the aux battery.

Tomorrow maybe I can figure this out, unless one of y'all know what I'm missing.

[kramttocs]

Thanks, Bill. That helps.

So the '96 PDB will have the PCM and fuel pump relays.

But I'm confused about what relays I have on the firewall right now. I've been saying there is a "trailer relay" but from my run through the '85 EVTM just now I don't see one. Instead the brake, turn signal, and backup lights run off of the same wiring that the truck's lights do. And the only relay I find associated with "trailer" is the aux battery relay that ensures when the engine is off a trailer or camper can only drain the aux battery.

Tomorrow maybe I can figure this out, unless one of y'all know what I'm missing.

Running lights (at least in 86)

[Gary Lewis]

Running lights (at least in 86)

Jein - In my case the relay is for trailer tail & marker lamps, but it is in the same place as the marker lamps. Thanks! So, I do have a trailer relay. Now the question is how many more.