OK, here is a doosey that has been hurtin a buddy of mine for a couple years now.
He pulls around a big Case gannon/tractor on a big tex trailer with a 2002 Ferd F450.
When he first got the trailer, he could lock up the tires no problem when he was loaded. Now, they barely do anything.
When he came to me with it, he had put brand new pads, magnets, backing plates, seals, turned the drums, etc. about 6 months prior. He had completely rewired the trailer with 12 gauge about 3 months prior. He also did some rewiring of the plug in and extended it up to the side instead of plugging in at the hitch since it was a gooseneck about 2 months prior. He had switched out brake controllers with a known good one of the exact same kind.
He says they work great with his son in laws truck but not with his.
Now, first thing I did was check the voltage at the magnet and it was a sketchy 5.5 VDC. So I check the plugin and it is at like 7.5 and then at the hitch and I have 12... bingo.
So, I rewire his old, corroded, connections and solder and shrink everything. We put a new fifth wheel plug at the back too, since there was an open in the factory adaptor. Then I check everything on the truck and I am loosing less than .5 volt from the batt voltage to the plug in with the controller manually pressed all the way.
I glanced over the stuff they wired on the trailer and it looked OK. So, now I check the voltage again and I am at 9VDC steady @ the magnet.
Still doesn't do it. They work, but do not help that much and definitely will not lock the tires up. Still OK with his son in laws truck.
So, today I start looking at all of the wiring on the trailer and find the ground that is used on the shiny new bolt has 7kohm of resistance and that the ball setup is not grounded worth a damn. So, I fix the ground by welding the bolt to the steel and use a star washer and solder and shrink all of those connections. Yay, less than one ohm between the trailer frame and the vehicle frame now and it does not go through the ball.
Still doesn't do it.
So, I crawl under the trailer and pull new wire through the axles, redo every single connection, soldering and shrinking...
Still will not lock them up or really do more than a light drag.
I now get about 10.4VDC w/o the engine running, at the magnet. About a 2 VDC total loss from the battery to the wheel.
So, I pull the battery out of my bucket truck and set up in the back of the truck and "hotwire" it directly to the plug from the trailer (completely isolating the truck from the trailer), while we are going down the road - trying to eliminate the truck as the problem. Same thing.
This is driving me batty. 10 volts should be enough to stop this sucker shouldn't it?
I would love to check and see what voltage his son in laws truck is getting to the magnet, but his controller went out today and the one they scavanged off another vehicle.... caused him to have the same problem as we have been having all along.
So, as a last resort we check the adjustment of each wheel. They are all fine. All are warm and there is plenty of dust on each wheel so they are all grabbing. We did notice that the linings were getting a little thin and the drums were fairly grooved - definitely time to get them done again. (kind of funny that they are wore that much not really working and only 6 months old)
Sorry for the long read, but I am trying to get all the info out there... I know how it is to try and diagnose an electric problem with limited info
Usually, I can figure this stuff out but this one's getting to me
Thanks in advance,
Vic
He pulls around a big Case gannon/tractor on a big tex trailer with a 2002 Ferd F450.
When he first got the trailer, he could lock up the tires no problem when he was loaded. Now, they barely do anything.
When he came to me with it, he had put brand new pads, magnets, backing plates, seals, turned the drums, etc. about 6 months prior. He had completely rewired the trailer with 12 gauge about 3 months prior. He also did some rewiring of the plug in and extended it up to the side instead of plugging in at the hitch since it was a gooseneck about 2 months prior. He had switched out brake controllers with a known good one of the exact same kind.
He says they work great with his son in laws truck but not with his.
Now, first thing I did was check the voltage at the magnet and it was a sketchy 5.5 VDC. So I check the plugin and it is at like 7.5 and then at the hitch and I have 12... bingo.
So, I rewire his old, corroded, connections and solder and shrink everything. We put a new fifth wheel plug at the back too, since there was an open in the factory adaptor. Then I check everything on the truck and I am loosing less than .5 volt from the batt voltage to the plug in with the controller manually pressed all the way.
I glanced over the stuff they wired on the trailer and it looked OK. So, now I check the voltage again and I am at 9VDC steady @ the magnet.
Still doesn't do it. They work, but do not help that much and definitely will not lock the tires up. Still OK with his son in laws truck.
So, today I start looking at all of the wiring on the trailer and find the ground that is used on the shiny new bolt has 7kohm of resistance and that the ball setup is not grounded worth a damn. So, I fix the ground by welding the bolt to the steel and use a star washer and solder and shrink all of those connections. Yay, less than one ohm between the trailer frame and the vehicle frame now and it does not go through the ball.
Still doesn't do it.
So, I crawl under the trailer and pull new wire through the axles, redo every single connection, soldering and shrinking...
Still will not lock them up or really do more than a light drag.
I now get about 10.4VDC w/o the engine running, at the magnet. About a 2 VDC total loss from the battery to the wheel.
So, I pull the battery out of my bucket truck and set up in the back of the truck and "hotwire" it directly to the plug from the trailer (completely isolating the truck from the trailer), while we are going down the road - trying to eliminate the truck as the problem. Same thing.
This is driving me batty. 10 volts should be enough to stop this sucker shouldn't it?
I would love to check and see what voltage his son in laws truck is getting to the magnet, but his controller went out today and the one they scavanged off another vehicle.... caused him to have the same problem as we have been having all along.
So, as a last resort we check the adjustment of each wheel. They are all fine. All are warm and there is plenty of dust on each wheel so they are all grabbing. We did notice that the linings were getting a little thin and the drums were fairly grooved - definitely time to get them done again. (kind of funny that they are wore that much not really working and only 6 months old)
Sorry for the long read, but I am trying to get all the info out there... I know how it is to try and diagnose an electric problem with limited info
Usually, I can figure this stuff out but this one's getting to me
Thanks in advance,
Vic
