'83 F150 and electric brakes.... - Diesel Forum

Kaliburz · 12-31-2007, 06:10 PM

Old F150 w/ an electric brake controller that was bought via JC Whitney 'years' ago. Installed and it worked great till recently. Have a 'weird' thing happening. It happens with any trailer I tow, so it's obviously in the truck.

When I push the manual activation bar on the controler, it activates the trailer brakes AND lights up the parking lights and brakes lights of the trailer AND the parking lights of the truck! Yes, weird. It's done this on two trailers I have towed. Never did before. The trailer brake wire is a 10 or 12 guage that I ran long ago, so it's not part of the OEM harness (heck, I don't think in 83 they were available wired for electric brakes). Any how, tested the harness where I tapped into the tail/stop/turn and had a buddy push the controller.... lights up.

Aside from the brake wire actually wearing through and making contact w/ the a tail light wire somewhere, is is possible the controller is is feeding back power to the brake system. I mean, there is a wire hooked up to the brake light system to activate the controller. I meant to disconnect the 'sense wire' (lacking the true name) from the truck brake light switch and planned to hit activate the controller manually to see if it was back feeding.

So anyone experience anything like this? [img]/forums/images/%%GRAEMLIN_URL%%/crazy.gif[/img]

Mr_Roboto · 01-01-2008, 01:08 PM

You probably have a rear bulb burned out and the filament is crossing between the brake and running light circuits.

As far as I know the brake lights are SUPPOSED to come on when the controller is manually activated. Brakes on, brake light on.

Kaliburz · 01-01-2008, 08:00 PM

Let me rephrase. When manually activating the brake controller, even the trailer parking and clearance lights turn on until you let go of bar. And it never use to.

Trailer and truck bulbs are fine. Last I drove the truck, parking lights worked and the left/right turn bulbs functioned all the way around.

When first installed, the brake lights NEVER turned on when the controller was manually activated.

I guess the only way I can find out, is if I clip the sense wire from the brake switch to the controller and manually activate the controller. If the truck light glow, has to be the trailer brake wire going to the back...a rub and cross. If not, my controller is bad.....

Mr_Roboto · 01-01-2008, 09:27 PM

Regardless the controller itself has no way of sending power to the running light circuit. You need to find where the power is feeding between the light circuits.

**bugman** · 01-01-2008, 09:45 PM

What happens when you just step on the brakes and not use the controler? The biggest problem that I see with trailers and their lights is a bad ground. Either from the truck or the lights themselfs. With a bad ground what ever light you light up will backfeed through the others to find a ground some where.

Jim

Kaliburz · 01-01-2008, 10:19 PM

Okay, just went outside and did some quick testing w/ a test light on the pickup. When the brake controller is manually activated, it is sending power through the sense wire connected to the pickup brake lights, so that is why the brake lights are lighting up. To my knowledge, this did not happen when the unit was 'new'. (Unless it is normal to activate brake lights when manually hitting the controller...I doubt it.) Another test I can do later, is to physically cut the sense wire that tells the controller to start braking. And then I'll manually activate it- just in case the feed back is coming from the plug end of the truck.

Prior observation of the trailer, when the brake controller is manually activated, the marker lights lit up. This happened on two different trailers, not just mine. But, when the trailer I was borrowing was used on a two different trucks, the controller there did not light up the marker lights on the trailer.

When I step the brakes normally w/out manual activation, the marker lights light up also.

So I have two issues. A bad controller that is feeding power back through the brakes and possibly something that sends power to the marker lights when the power get sent to the brake lights.

When we first looked at the truck wiring and plug, the ground that runs to the plug to the frame looked fine. The trailer was grounded in different spots to the frame and then the trailer plug was grounded to the frame.

There is something that just occurred to me as I finished typing all this. Last time I was under the truck looking at the old plug (plastic plug body), I noticed it was dirty where the wires plugged into the back of the truck harness. I cleaned that all off and there was a hairline crack in the plug, but didn't think nothing of it. I wonder if that crack allowed corrosion to take place in side, and some how, the pin to supply power to the electric brakes is jumping over to the tail and brake light pins. I guess if I clip the sense wire and it still feeds back (activates the truck lamps, then I know it's either in the wire or plug....)

Or, as mentioned, a bad ground that's really acting weird...

Mr_Roboto · 01-01-2008, 10:27 PM

I haven't dealt a lot with electric brake controllers. However my neighbor gave me the task of working on his dumptruck and trailer with electric brakes. And with the controller on manually, the truck and trailer brake lights come on.......

Is it possible you just never noticed them coming on?

Kaliburz · 01-01-2008, 10:47 PM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mr_Roboto</div><div class="ubbcode-body">I haven't dealt a lot with electric brake controllers. However my neighbor gave me the task of working on his dumptruck and trailer with electric brakes. And with the controller on manually, the truck and trailer brake lights come on.......

Is it possible you just never noticed them coming on? </div></div>

It's possible I never noticed. Most of my towing is during day light hours and if it's dark enough, I turn on the parking lights (which would mask the brake lights going on when manually activated). Funny thing is, the two other controllers in my friend's truck & his fathers have NEVER turned on the brake lights when manually activated. Maybe each manufacturer is different.

If I assume that this controller does light up the brake lights when manually activated is normal, the next question would be, where is the feed back that is allowing electric brake power to get to the trailer marker lights? Because when I step on the truck brakes, and the controller activates 'automatically', you can see a marker light slowly glow and the longer you step on the brake, the brighter it gets. Obviously, power is feeding to the marker lights from the electric brake circuit.

I think this weekend I might back up to the trailer and plug it in and do some more diagnostics. Usually I don't think about it until I have a trailer hitched and on the road. Then it hits me and I think, lets hope the police don't notice my trailer marker lights going on w/ the electric brakes..... (I don't tow that often).

eta-
I hate dealing w/ electrical issues.....

Mr_Roboto · 01-02-2008, 11:23 AM

From your description I believe the power is coming not from the brake light circuit, but from the brake APPLY circuit (since the lights slowly get brighter). Many controllers use a "progressive" apply, where they start light then slowly apply the brakes harder (more voltage).

I suspect a ground problem between the truck and trailer. Try connecting the two with a pair of jumper cables and see if the problem continues.