| Author |
Message |
Dave Hartshorne (24.209.222.149)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, July 05, 2004 - 10:22 am: | |
I have a Scenicruiser I am using to tow a 25 foot trailer, and having problems getting the trailer brakes to function. I can activate them using the manual overide, but can not get them to operate off the brake pedal. Does anyone have any tips on where to connect the brake control wire into the bus. Thanks |
Peter Broadribb (Madbrit) (67.136.117.49)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, July 05, 2004 - 11:31 am: | |
Dave,
I asked Tecomsha, who manufacture the controllers, and their reply was to connect it to the brake light switch circuit as per a normal vehicle.
Most modern controllers have the intensity and speed of application controls to balnce the way the brakes react, so with a little fiddling, you should be able to get them to work.
Peter. |
Dave Hartshorne (24.209.222.149)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, July 05, 2004 - 11:49 am: | |
Thanks Peter, I have connected them into the brake light switch on the dash, and also tried the common wire to the brake/turn line, with no succes. I am going under the bus to try and find a direct line from the brake pedal but have not found an easy way to gain access, but will post what I eventually find.
Cheers,
Dave |
TWO DOGS (63.185.65.39)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, July 05, 2004 - 1:00 pm: | |
wait a minute here...you have elec. brakes on your trailer ,correct?...on all my elec. brakes on trailers,there is a control box that bolts to the sreering collum ,that has a hook-up for hyd. brakes,(hyd. brake fluid)....If I'm incorrect about this....I apoligize in advance... |
FAST FRED (4.245.230.86)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, July 05, 2004 - 1:56 pm: | |
The signal to begin electric trailer brakeing comes from a brake light circuit.
On hyd brake vehicles anywhere after the master cylinder pressure switch works fine.
On most GM there is an air operated switch that actuates the brake lights , after a few psi are used to brake the coach.
Tie in there to the electric controller , and you will be fine.
Electric controllers have to be somewhat matched in amp cap to weather the trailer has 2 or 4 or 6 brakes.
The places that sell 40ft RV trailers is a better place to shop than the RV store.
Electric brakes need far far more work to keep operating than most think.
Have you inspected each wheel for function?
FAST FRED |
Dave Hartshorne (24.209.222.149)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, July 05, 2004 - 10:30 pm: | |
Thanks for the response guys, I have all new brakes on the trailer and it works great behind my other vehicles. I have still been unable to trace the pressure swith in the air line. Under the floor below the drivers seat there are 6 or 7 different pressure switches, and none are easy to get to, so I need to get air pressure going and put volt meter across each one with the wife pressing the brake pedal, to figure out what each does. Had the fuel system appart today putting a new fuel pump on and replacing the old filters with spin on's so will be tomorrow before I get it running. Bus is positive ground but assume it does not matter which side of the switch I connect into once I find the right one?
Appreciate the suggestions, Dave |
Jim Stacy (209.247.222.102)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, July 05, 2004 - 10:55 pm: | |
"Bus is positive ground" Bingo!!!
Any electronic brake controller I've worked with will not work on reversed polarity. They are electronically switched not mechanically, and are polarity sensitive. Why are you running a coach on positive ground? They are usually easy to change.
Jim Stacy |
Gary McFarland (Gearheadgary) (209.128.79.46)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, July 05, 2004 - 11:16 pm: | |
Are you looking for a wire that goes on and off with the brake?
Positive Ground? Really? (I'm a Bluebird Guy).
If you don't want to convert to neg gnd (Why wouldn't you) you can rig a relay, like a bosch relay to do the brakelight signal thing, but then you have to be careful about isolation, etc...
Positive ground, Really?
Gary |
TWO DOGS (63.185.80.196)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, July 05, 2004 - 11:58 pm: | |
I still think something is not correct here....the way elec. brakes are...(hooked up to the box on the steering collum)...the amout of brake fluid pressure,determines how hard the elec. brakes are applied....just 'straight' 12 volt to the brakes would just lock them,thats worse than no brakes... |
FAST FRED (4.245.149.71)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 06, 2004 - 5:38 am: | |
No the electric controllers apply the brakes based on time.
AS juice goes to any break light the controller ramps up to a max current.
The RATE , and TOTAL current are both adjustable on the electric controller.
There is a large difference between how much breaking power you can allow on an empty trailer compared to a loaded one.
FAST FRED |
Don KS/TX (66.82.9.64)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 06, 2004 - 7:29 am: | |
Two Dogs, you are talking about the old ones that aren't used much any more. They have stopped tapping into the brake line for some years now, and use the brake light controller now. |
Gary McFarland (Gearheadgary) (68.79.122.176)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 06, 2004 - 9:03 am: | |
I had always used the hyd ones too, I bought the new wells cargo a few months ago and also had one of the new electric controllers installed.
Works like a charm.
Gary |
RJ Long (67.181.211.253)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 07, 2004 - 12:38 am: | |
Dave - IIRC, the switch that actually activates the brake lights is located on the bulkhead back by the rear axle. . . Follow the air lines from the drive axle brakes back to the bulkhead and you should find it.
Are you sure your Scenic hasn't been converted over to negative ground?
Gary - Yes, the Scenicruiser and the 4104 were both originally positive ground vehicles. The vast majority of them have been converted, but it appears that Dave's hasn't been. . . yet!
Two Dogs - Since the introduction of automotive anti-lock braking systems, the type of brake controller you're talking about has been discontinued. There are, however, hydraulic trailer braking systems that are actually mounted to the hitch assembly, and are fully self-contained and self-proportioning. Works off the normal forces applied to the hitch. IIRC, U-haul has them on their car-hauler trailers, as an example.
HTH,
RJ
PD4106-2784
Fresno CA |
Gary McFarland (Gearheadgary) (68.79.122.176)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 07, 2004 - 12:49 am: | |
Hmmm....I never thought about the effect antilock braks would have on a brake controller,
Live and learn (Hopefully)
Gary |
RJ Long (67.181.211.253)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 07, 2004 - 1:59 am: | |
Gary -
This is the info I got from the fellow who owns the business that installed the hitch on my pickup:
Prior to anti-lock brakes, actually, prior to dual master cylinders, some of the older trailer brake controllers used a sensor mounted on a "t" fitting in the brake line coming off the master cylinder to measure the output line pressure, and that sent a variable signal to the electric brakes.
When the dual master cylinders started coming online is when the shift began to controllers operated by the brake light switch, with a little pendulum inside to sense the braking loads, and vary the signal accordingly.
With anti-lock brakes, the traditional master cylinder operates under very high pressures, and is electronically-linked to the auto's computer, making a hydraulically-sensed trailer brake controller virtually impossible.
So now we have the simple, brake-lite switch operated units that are a vast improvement over the earlier models.
At least, that's the way it was explained to me. . .
FWIW,
RJ
PD4106-2784
Fresno CA |
Dave Hartshorne (24.209.222.149)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, July 09, 2004 - 7:00 am: | |
Hey guys, thanks for all the tips, spent a day looking under the floor in front before I saw your posting RJ, took me straight to the switch on the bulkhead. My bus has not been converted to negative ground, so until it has I wired an isolated relay off the brake switch on the bulkhead and seems to have it nailed. Heading out this morning so we will know for sure in a couple of hours. Again, thanks for all the help. Dave |