-
Brake light pressure switch
Does anyone have a wiring diagram of the brake pressure switch for a 1991 XL 40? I found 2 loose wires in the side compartment. Replaced brake pressure switches but lights are still stuck on. Thanks
-
13 Replies
-
On my Bus there is a square button white about 1.25×1.25 and it says Decel and it’s for turning brake lights on going down a hill with jake on. When we 1st got the bus the dog had pushed down button and red brake light on dash was on, couldn’t figure it out, then I saw button down, it should be a momentary button, I got it to come up light went off so I sprayed a little WD40 around switch now you push it and it springs back up.
-
Art,
I had some thoughts about the white button also that were incorrect. That is not for your brake lights. It works with the cruise control to decelerate speed when the CC is set.
Jeff and Lindsay
91 Marathon XL -
Thanks! I don’t have that on mine. It doesn’t have cruise control.
-
Did you check the brake light relay in the electrical panel above the engine? The relays can stick closed. Tapping it lightly with a screw diver handle can temporarily unstick it.
-
Apples and oranges.
The reason brake lights are on is because a relay or switch in the system is not open. Find which switch or relay remains closed when the brakes are not on and that is the problem.
The square white button is part of the Cruise Control and its purpose is to disengage the cruise control without stepping on the brake pedal.
Having said that if that is the problem with the brake lights always on, then it is possible to determine by seeing if the cruise control works, and if it does, just verify the white button does disengage the cruise by pressing it.
If the coach has a jake or retarder there is a relay in the rear electric box that activates the brake lights when the jake or retarder engages even with your foot off the brake. That could be a potential culprit also.
-
I did not know it disengaged the cruise
-
That is the purpose of the button and unless the relay that turns on the brake light has been removed it likely activates the brake lights when pressed.
Later model coaches have a brake light icon on the annunciator panel so you can see when the brake lights are on, such as activation of the jake or retarder, or when disengaging the cruise using the switch. It is the activation of brake lights that disengages the cruise.
-
I tapped on relays no change. We can eliminate cruise I don’t have it. Jake brake I always leave on. Not sure which relay it is. I found two loose wires at pressure switch someone has marked B. This just came out of the blue not sure what happened to cause it.
-
-
After further examination the brake lights will go on and off when I turn my Jake brake switch on and off. Any ideas????
i did find the relay is labeled R26 in the panel over the engine! Thanks for that tip!
-
Buses equipped with a Jake have a relay that lights the brake lights when the Jake is engaged.
If you can turn off the Jake and the brake lights go off it is likely your problem relates to the relay. Look on your electrical panel in the rear box to see which relay is dedicated to the Jake brake lights and check it or remove it.
-
Thanks Jon! Will do
Jeff and Lindsay
91 Marathon XL -
Mike,
Are you saying the brake lights go off and on with the jake switch when bus parked and not touching the throttle? If so it sounds like a bad 0 throttle switch also known as a buffer switch.
Log in to reply.