tandem axle brake wiring... series between front and back?
I decided to chase an issue with brakes today. In the past, the trailer "pigtail" had an issue where it was "compromised" as it passed by the battery tray such that someone (previous owner) had spiced a few wires... one of course was the brake wire (ie. blue). I had corrected this work with new splices and better weather proofing.
I noticed this spring that the brake controller had to be increased to get an "equivalent response" to previous years (year three). On the Prodigy P2, it went from 9 to about 12 now.
Previous park / storage for last month, we noticed a loss of brake light on one side. Some playing with bulbs (swap) pointed to the TV / trailer connection. Some "light cleaning" with wd40 restore the lights but gave "notion" to perhaps a dirty plug connection that needed addressing. Hence, how I got here.
The trailer is a terry dakota 20 footer ... 2006 2007 depending on what "marketing" you believe... :-)
So I start looking, thinking that perhap poor connection at the plug were to blame for all things happening now, ie. the brake "issue", lights. Measured the resistance at the trailer plug... 3.2 ohms... ? seems high. same after cleaning with small file.
look in the dexter book, says each brake is 3.2 ohms... what! (more explicit than that... :-) )
So I pull apart "surgical area" of the cable... well wrapped with tape and interior "cast" of bicyle tire tube. The area seems pretty good but get down the to crimp connectors and find the blue wire connector / crimp was loose and wires only lightly touching.... guess my attempt at a crimp was just as good as the previous owner... :-)
Get a new crimp and re-crimp things... with a better crimper than my earlier flat stamped steel one. Great, so check out the resistance at the plug. Hmmm, resistance has dropped, as expected, now to 1.6 ohm. Kind of strange that it is "exactly half" of the 3.2 / brake resistance that the book indicates for one brake wheel.
I check out the rest of the cabling where visible along with jacking the wheels off the ground and spin / brake test each wheel. All work / lock depending on voltage setting, including breakaway switch pulls / test.
Looking at the wiring at the front axle, driver side, there is one pair of wiring coming from the frame of the trailer, I assume, feed.
The pair is then mated with a pair of wires that go to the brake drum on that side along with a second pair of wires going thru the axle to the far side drum / brake... basically 3 wires at each "splice pack".
Similar wiring shows up at the second axle on the driver's side.
I haven't traced thru the wiring channels on the frame of the trailer or the wiring box yet, but based on the measurements and the fact that there are only 3 pair of wires at each axle, it would almost appear that the front and rear axle are wired in series.
Not sure is this is true yet as it will take some work to "tear into" the frame wiring which I am not sure that I want to do at this point... kind of leave well enough alone sort of thing.
My question would be... Is series wiring of the brakes on tandem axles an "option" that people (builders) can use... the brake drum wiring at the axles and drums appears to be "original" based on crimps packs used (I have never seen that kind of pack available for general public...flat pack with three wires on one side).
Any comments of this setup. I would think it lowers braking current which might be useful such that the controller has a broader "control range" to prevent such that things like grabbing / locking may be reduced possibly.
thanks for any comments / guidance.
I noticed this spring that the brake controller had to be increased to get an "equivalent response" to previous years (year three). On the Prodigy P2, it went from 9 to about 12 now.
Previous park / storage for last month, we noticed a loss of brake light on one side. Some playing with bulbs (swap) pointed to the TV / trailer connection. Some "light cleaning" with wd40 restore the lights but gave "notion" to perhaps a dirty plug connection that needed addressing. Hence, how I got here.
The trailer is a terry dakota 20 footer ... 2006 2007 depending on what "marketing" you believe... :-)
So I start looking, thinking that perhap poor connection at the plug were to blame for all things happening now, ie. the brake "issue", lights. Measured the resistance at the trailer plug... 3.2 ohms... ? seems high. same after cleaning with small file.
look in the dexter book, says each brake is 3.2 ohms... what! (more explicit than that... :-) )
So I pull apart "surgical area" of the cable... well wrapped with tape and interior "cast" of bicyle tire tube. The area seems pretty good but get down the to crimp connectors and find the blue wire connector / crimp was loose and wires only lightly touching.... guess my attempt at a crimp was just as good as the previous owner... :-)
Get a new crimp and re-crimp things... with a better crimper than my earlier flat stamped steel one. Great, so check out the resistance at the plug. Hmmm, resistance has dropped, as expected, now to 1.6 ohm. Kind of strange that it is "exactly half" of the 3.2 / brake resistance that the book indicates for one brake wheel.
I check out the rest of the cabling where visible along with jacking the wheels off the ground and spin / brake test each wheel. All work / lock depending on voltage setting, including breakaway switch pulls / test.
Looking at the wiring at the front axle, driver side, there is one pair of wiring coming from the frame of the trailer, I assume, feed.
The pair is then mated with a pair of wires that go to the brake drum on that side along with a second pair of wires going thru the axle to the far side drum / brake... basically 3 wires at each "splice pack".
Similar wiring shows up at the second axle on the driver's side.
I haven't traced thru the wiring channels on the frame of the trailer or the wiring box yet, but based on the measurements and the fact that there are only 3 pair of wires at each axle, it would almost appear that the front and rear axle are wired in series.
Not sure is this is true yet as it will take some work to "tear into" the frame wiring which I am not sure that I want to do at this point... kind of leave well enough alone sort of thing.
My question would be... Is series wiring of the brakes on tandem axles an "option" that people (builders) can use... the brake drum wiring at the axles and drums appears to be "original" based on crimps packs used (I have never seen that kind of pack available for general public...flat pack with three wires on one side).
Any comments of this setup. I would think it lowers braking current which might be useful such that the controller has a broader "control range" to prevent such that things like grabbing / locking may be reduced possibly.
thanks for any comments / guidance.
