Maintenance manual for sunray hfc4da1-2c china-IV diesel engines
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15.
DTC P0504 Unreliable comparison between main and auxiliary brake pedal signals
Fault Description: The brake switch detects the brake pedal action and sends the signal to ECU. The brake switch is
equipped with two switches, viz. main and auxiliary brake switches. When these two signals are input, these signals
are determined by ECU to be normal brake signals. The switch signals are relevant to the accelerator pedal, for
controlling the fuel amount during braking. There should be no failure when you operate the accelerator pedal at the
point of depressing the brake pedal, but the fuel amount shall be reduced when you operate the accelerator pedal with
the brake pedal depressed. If the voltage signal of brake switch is inconsistent with the actual, the DTC shall be
generated.
Diagnosis Hint: Check the wiring connector for poor contact, distorted or damaged terminal.
Terminal ECU
K17 Main brake switch signal
K80 Auxiliary brake switch signal
Main brake switch
Auxiliary brake switch
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