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Topic: Trailer brake controller with retarder (Read 1007 times) previous topic - next topic

Trailer brake controller with retarder

I'm using my 2001 U320 to pull a 9,000 lb race trailer with electric brakes.
My local dealer installed a Tekonsha P3 brake controller.
The brake lights must come on when the manual retarder is engaged which activates the trailer brakes.
It's a proportional system and is not sending full brakes to trailer, but I don't think having the trailer brakes on (even lightly) for 15-20 minutes down a steep grade is the right thing to do.
How do I stop the trailer brakes from coming on?

Steve

"Rocket"  2001 3610 U320 IFS  #5907
Car crazy guy with too many toys to list here.

Re: Trailer brake controller with retarder

Reply #1 –
That's why I went with air/hydraulic brakes on my stacker.  Can you cut the brake circuit wire and just use the controller in manual mode?
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Trailer brake controller with retarder

Reply #2 –
You can install a diode in the line from the brake switches so that the retarder when it applies the lights does not activate the brake controller.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: Trailer brake controller with retarder

Reply #3 –
Your coach probably has 2 brake light switches, 1 that is activated by the retarder and 1 that is activated by the application of the service brake.  If the sense wire for the Teknosha is connected to the output of the service brake switch, it will not activate the trailer brakes unless you step on the brake pedal.

These 2 switches are side by side under the dash.
Monti
2015 Born Free Triumph Royal 4x4
Previous:  2000 U320 3600

Re: Trailer brake controller with retarder

Reply #4 –
I think I have wiring diagrams with the coach I will see what I can find.

Steve
"Rocket"  2001 3610 U320 IFS  #5907
Car crazy guy with too many toys to list here.

Re: Trailer brake controller with retarder

Reply #5 –
If I remember right, both brake light switches are used to turn on the brake lights so if one fails the other will apply the brake lights. the retarder also has a switch to apply the brake lights You have to cut one of the wires from the brake switch and install the diode to keep the brake light wires from backfeeding from the retarder to brake control. This is only a problem on coaches that have the brake lights turned on by a retarder or engine brake. On my 98 I could only use a wire from one switch as the King cruise control got a ground signal through the brake light bulbs.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: Trailer brake controller with retarder

Reply #6 –
We put in a dash switch to optionally not turn brakes lights on when retarder is active.  We did it for freeway driving to keep retard from turning off cruise control.  If driving on cruise with joy stick not fully off, and the highway goes down even a small hill, the throttle goes to idle position, retard will kick in and when the highway goes level or starts to climb again, we used to unexpectedly find cruise turned off.  With the new retard/brake light switch, we can prevent cruise from turning off.

Always driving with joy stick off eliminates the need for the switch.  On our coach there is a retard brake light relay next to the two (front & rear) air brake pressure switches, all of which are located high up on the front panel of the forward street side bay (just behind the headlights).  Running a pair of wires from this retard relay up to dash gave us our option.

Some coaches where joy stick was added post-production, the retard brake light relay was not added, so these coaches do not ever turn on brake lights when their retarder is activated.

Re: Trailer brake controller with retarder

Reply #7 –
Quote from: red tractor –
If I remember right, both brake light switches are used to turn on the brake lights so if one fails the other will apply the brake lights. the retarder also has a switch to apply the brake lights You have to cut one of the wires from the brake switch and install the diode to keep the brake light wires from backfeeding from the retarder to brake control.
Ron or anyone else, do you recall a part number from diode used?  Thanks, David
David & Lou Ann Bouchard
Summer: Mount Vernon, Ohio
Winter: RiverBend Motorcoach Resort  LaBelle, Florida
2003 U320 38' Build #6174 "Willie"
2013 Cadillac SRX Toad
MC #17151 FMCA #F431393

Re: Trailer brake controller with retarder

Reply #8 –
I got a 6 amp diode from radio shack don't know the part number, but you could also use a diode like they use to wire a car for towing, like from roadmaster
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins
 

Re: Trailer brake controller with retarder

Reply #9 –
Thank you Sir
David & Lou Ann Bouchard
Summer: Mount Vernon, Ohio
Winter: RiverBend Motorcoach Resort  LaBelle, Florida
2003 U320 38' Build #6174 "Willie"
2013 Cadillac SRX Toad
MC #17151 FMCA #F431393