Discussion in 'Touring Models' started by ozzy, Jan 1, 2011.
Ihave a code P0572 brake switch low what does that mean
To me the Switch is always shorted to ground. Sounds like another late model switch has bit the dust.
This info is out of the 2009 Touring Electrical Diagnostic Manual.
There are two stop lamp switches. The front stop lamp switch is a mechanical switch located on the right hand controls. The rear brake switch is a pressure switch located in the brake line under the exhaust pipes.
On vehicles not equipped with ABS, when the stop lamp switches are closed they supply power to the coil side of the brake relay. This energizes the brake relay and supplies power to the stop lamp. The stop lamp switches also supply an input to the ECM.
On vehicles equipped with ABS, when the stop lamp switches are closed each switch supplies a separate input to the ABS module. Power is also supplied through the ABS diode pack to the ECM (as a brake input) and to the brake relay.The brake relay energizes and supplies power to the stop lamps.
During an ignition cycle, the ECM must receive a valid brake switch input. During the same ignition cycle the vehicle has to reach 31 MPH (50 km/h) in third gear or higher and return to a stop three times with out any brake switch signals in order to set DTC P0572.
P0572 Brake switch input error
• Make sure the rear brake reservoir has the proper amount of brake fluid, and there are no apparent leaks. If fluid is low, the rear brake switch may not receive sufficient pressure to actuate the switch. Replenish brake fluid in
the brake reservoir(s), as necessary.
• An intermittent may be caused by poor connection, rubbed through wire insulation or an inoperative wire inside the insulation.
Check for the following conditions:
• Poor connection: Inspect component and harness connectors for backed out terminals, improper mating, inoperative locks, improperly formed or damaged terminals, poor terminal-to-wire connection and damaged harnesses.
• Fluid leaks: Check the rear brake switch for fluid leaks around the seal of the switch. Refer to the service manual to repair a fluid leak.
1. When checking the (O/W) wire, from the accessory fuse for a short to ground, remember to check the wires on the other side of the switches for shorts to ground as well.
These circuits could cause a short to the accessory fuse but only when the switch is closed. The accessory fuse circuit supplies power to the cigar lighter, horn, left and right turn signal switches, front and rear brake switches
and the cruise control switch.
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