Common Brake Wiring Gremlins?

[rlindberg]

My '66 overlander brakes didn't work when I got her. I just installed a new brake controller and pulled apart the plug and checked connections there, but still no brakes. Is there any common problems that I can start with before replacing pieces? I have lights so I know at least something is getting thru the plug. Is there a ground in the cord itself? I've heard some older trailers grounded to the ball of the tow vehicle? Also, there is a (i think) selonoid with wires coming ouut of it by the jack and I was wondering if this was a sort of breakaway switch....or something totally different? Should I start with replacing the plug then keep working my way back, or replace the wiring to the brakes alltogether? If the latter, is there a good "kit" out there?

Thanks in Advance,

Randy Lindberg

[overlander64]

Greetings Randy!

I am wondering if you may be encountering a problem with the Airstream wiring color/function of wires compared to the modern industry standard. In 1966, Airstream used its own wiring pattern that is not the same as today's industry standard. You can find a pdf file linked below that will identify how your coach was originally wired. You can compare this data to the Marks RV data to get an idea of some of the possible issues.

There is also a possibility that a wire may be loose or disconnected in the umbilical cord junction box. The junction box is usually found in the front curbside corner of the bellypan -- it can be identified as a recctangular "patch" on the underbelly skin.

If someone has at some point pulled out the breakaway switch and didn't get the pin back into it quickly enough, your coach's brake magnets may have burned out. Another possibility is that a blow-out on one of the wheels may have sent tire rubber into the brake wires severing one or more of them.

Good luck with your investigation!

Kevin

[dwightdi]

The first thing is to see if the brakes really have voltage applied. The brake lights lighting up does not mean there is voltage to the brakes. The brake controller does that. You need to read the output on the brake controller in the truck while you apply the brakes. If that reads the proper value according to your owners manual then the next thing is to see if the brake magnets are being activated. You can listen to them clank when the brakes are applied. If they all clink then there might be something mechanically wrong with the brake backing plate. If they do not clink you have an electrical problem. The brakes wires are usually just wire nutted together. Back off the nut and measure whether you have the proper voltage applied when someone else applies the brake. You should check all wirenuts for tightness while you are down there. You should also check the quality of the grounds and all brake connectors with an ohmmeter. If this is all sounding like you do not understand, take it to your local RV dealer. Brakes are a very important safety feature and doing it wrong can possibly cost you your life. This is one job you do not want to learn by trial and error. For less than $50 per wheel you can buy all new backing plates with new brakes installed. You only need to remove the wheel and brake drum plus 4 bolts to change them. It is a quick afternoon's work. Many experienced Trailer aholics change the whole backing plate assemby to gain the maximum reliability from their brakes.

[rlindberg]

O.K., here's where i'm at. We've got power to the blue wire under the belly pan curbside when I hit the brakes on the controller. Then, we've got power at the rear on the panel by the battery. I've got no power anywhere at the breakaway switch and no power at the brakes (I have the drums apart checking pad wear and replacing adjusters, springs). I figured the blue wire went from belly access to rear panel, but there must be somwhere it splits after the panel to each side? Is there another access point/junction I'm missing? Also, how do I check the magnets to see if they're good?

Thanks!

Randy Lindberg
randylindberg@hotmail.com