2003 Sport Trac Brake Controller / Towing

[MD McLaughlin]

Hello to all. New member, first post.
I'm trying to get my 2003 Sport Trac ready to tow a 1988 15' Lynx Prowler that weighs just under 2k lbs. Had a local garage wire in a 7 blade recepticle to match the trailer. Also bought a Hopkins inertia brake controller and had a pig-tail harness wired in as well. Wiring appears correct as all lights work on the trailer properly... without the brake controller plugged in. Brake controller wouldn't work. I think the garage fried the controller. They said it was melting the brake switch wires. When I checked it out, I found the red controller wire that supposed to go the brake switch was putting out 12v. Not sure if that was correct. They may have also hooked the red wire to the wrong brake switch wire. Looks like they were trying to splice it to the green/red stripe wire, which is now melted looking. Which wire is the "cold side" wire on the brake switch? Have a new controller but don't want to hook it up wrong again.
Any other tips on towing with this vehicle would also be appreciated. Truck has 4.0 L with 4x4. Just installed load leveler type rear shocks. Looks like it has a factory tranny cooler.

 

[ncranchero]

Light green/red is the hot side, light green is the cold side, as you put it. They spliced it to the wrong side of the brake switch, as you suspect.
......CONTROLLER COLOR...............................................FORD COLOR
White wire – ground/negative terminal (-) on battery..............White
Blue wire – trailer electric brakes.........................................Blue
Black wire – positive terminal (+) on battery..........................Red (through a 20 amp breaker)
Red wire – cold side of stop lamp switch or brake light.............Green on brake pedal position switch

From the Agility instruction sheet:

NOTE:
• Some late model Ford/Mercury trucks and sport utility
vehicles have 2 or more stop lamp switch wires. For
proper operation, use the light green wire. The other wire
is red with a green stripe. This wire goes directly to
ground when not in use. Splicing into this wire will shortcircuit
your brake control and possibly damage the unit.

It doesn't go to ground on the Sport Trac but the instructions specifically say LIGHT GREEN WIRE.

 

[MD McLaughlin]

Thanks. Does this mean the light green wire would generate an output to the controller when the brake pedal is pressed? Got an idea of what kind of output could be expected? What seems odd, is the red controller wire is about a 12 or 14 gauge wire, whereas the brake switch wires are about 18 or so. Seems kind of a mis-match to wire a 12 gauge to an 18.

 

[ncranchero]

Yes, it's sending a signal to turn on the brake lights AND will send a signal to power the controller. Are all of the controller wires not the 12-14 gauge size? I suspect that has more to do with manufacturing than need. The high amp current is on the other 3 wires.

The controller, if it's like all of the inertia models I've seen, applies braking force based on the position of a swinging pendulum. (which it HAS to be mounted/adjusted properly) If you were going down a steep incline the pendulum could swing forward, applying braking force when you really weren't braking. Thus the need for the signal from the brake light switch to tell the controller HEY STOP!

 

[MD McLaughlin]

2003 Sport Trac Brake Controller

I've done some further research and had the wiring looked at by a auto-electrician. I'm still confused however. First, I mis-stated that the original garage wired into the green/red wire. The green/red wire is exactly the hot side and is not the wire that tied into. What they actually wired into looks to be the red/green wire. This is the wire referred to in the controller instructions as to not use as it's connected directly to ground. When the brakes are applied, the light green wire and the red/green wire show 12v.
So, I hooked up the controller without wiring it into the brake switch. The red wire from the controller has no voltage until you press the manual brake switch on the controller, at which point, the red wire puts out 12v and the blue wire to the trailer brakes goes from about 4v to 12 v. I assume this is the way it's supposed to work.
What confuses me still; Is the red controller wire both an output (when the manual brake button on the controller pushed), then an input wire when spliced to the green brake switch wire (getting a 12v input from the activated brake switch)? IF this is correct, I can slice into the solid light green wire and everything should be OK.

The "expert" I talked to told me he was going to wire into the red/green wire. Same mistake made by the original garage.

 

[ncranchero]

When the brakes are applied, the light green wire and the red/green wire show 12v.(this is correct)
So, I hooked up the controller without wiring it into the brake switch. The red wire from the controller has no voltage until you press the manual brake switch on the controller, at which point, the red wire puts out 12v and the blue wire to the trailer brakes goes from about 4v to 12 v. I assume this is the way it's supposed to work.(this is also correct)
What confuses me still; Is the red controller wire both an output (when the manual brake button on the controller pushed), then an input wire when spliced to the green brake switch wire (getting a 12v input from the activated brake switch)? IF this is correct, I can slice into the solid light green wire and everything should be OK.(Right on the nose)

The "expert" I talked to told me he was going to wire into the red/green wire. Same mistake made by the original garage."Definition of EXPERT: EX= a has been, spurt= a drip under pressure!

We're talking strictly about the RED wire from the controller here.
In the diagram below, notice the Light Green/Red(stripe) wire feeding 12V TO the switch. No current passes through the switch until you depress the pedal. Then current flows OUT on the Light Green wire(to the brake lights).
Attaching the RED controller wire to the light Green wire tells the controller you want to stop, thus allowing the internal pendulum of the controller to apply braking current to the trailer brakes.
MANUALLY sliding the over ride lever sends the same message to the pendulum BUT in doing so energizes the red wire, telling the BRAKE LIGHTS to come on...........

From FOMOCO

I don't know what this Red/Green Stripe wire is for. I may could identify it with a photo, IDK.

 

[MD McLaughlin]

2003 Sport Trac Brake Controller

Thanks. Very helpful info. You confirm what I was wondering. Red controller wire receives a 12v signal when the brake pedal is pressed (when correctly connected to the light green wire). Then it also sends a 12v signal to the brake lights through the light green wire when the manual controller brake switch is pressed. Light green/red stripe wire is incoming 12v.
The red/green stripe wire appears to be the one mentioned in the brake controller instructions you posted earlier, warning not to connect the red wire to it. Not sure what it does but it shows 12v when the truck brake is pressed. This could confuse someone into thinking they had the right brake switch wire.

NOTE:
• Some late model Ford/Mercury trucks and sport utility
vehicles have 2 or more stop lamp switch wires. For
proper operation, use the light green wire. The other wire
is red with a green stripe. This wire goes directly to
ground when not in use. Splicing into this wire will shortcircuit
your brake control and possibly damage the unit.

Thanks.

 

[ncranchero]

I don't know about that red/green stripe wire either. The diagram I posted from the 2003 Service manual doesn't support a R/GN wire on the BPP switch. Never looked at the switch on my truck. Now I'll have to !

 

[MD McLaughlin]

Sport Trac Towing

Ever tow much with your Sport Trac? As soon as the brake controller is complete, I have a 2000 lb 15' Lynx Prowler camper I plan to drag around. I've only been around town with it in tow. Seem to do OK but, can't tell how it will do trying to go down a highway or going up hills. Although the truck is rated to tow over 5,000 lbs, I've never heard too any good towing reviews.

 

[ncranchero]

Frankly the 5R55E and it's legendary troubles scares me too much to tow our car trailer loaded. The trailer weighs 1500 lbs and the Trac pulls it, empty, like it's not back there. Put a vehicle on the trailer and it pushes or exceeds the rated tow capacity. I do pull a heavily built 6' x 8' utility trailer with my zero-turn mower and have no trouble at all. You should have no trouble with a 2000 lb camper.