019-088   Brake Pedal Position Switch

General Information

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 CAUTION 

When troubleshooting the brake line switch circuit, make sure the brake pressure switch is identified. The vehicle brake light pressure switch, which is not a part of the Signature system, is commonly mistaken for the brake line switch used in the Signature system.

The brake pedal position switch detects the position of the service brake pedal. Certain features such as cruise control and PTO respond to the state of the brake pedal position switch and disengage when the brakes are applied. The circuit has a normally-closed switch, switch return wire, and brake pedal position switch signal wire of the OEM harness. The brake pedal position switch is mounted in the low pressure side of the vehicle pneumatic brake system. When the vehicle brakes are applied, the normally-closed switch opens and disables the cruise control operation.

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Remove

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 WARNING 

To avoid personal injury or death, do not apply the vehicle brakes when the switch is removed from the brake line fitting.

Disconnect the OEM harness from the brake pedal position switch.

Remove the brake pedal position switch from the fitting.

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Install

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Install the new brake pedal position switch into the fitting according to the vehicle manufacturer’s procedures.

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Connect the two wire connectors to the brake pedal position switch.

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Resistance Check

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If INSITE™ is available, monitor the brake pedal position switch for proper operation. If not, follow the troubleshooting procedures in this section.

The brake pedal position switch (1) will be located in the vehicle brake line (2). The location will depend on the OEM installation procedures.

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Disconnect the two wire connectors from the brake pedal position switch.

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Connect the probes of the multimeter to the brake pedal position switch terminals.

Measure the resistance.

The multimeter must show a closed circuit (10 ohms or less) when the brakes are not applied. If the circuit is not closed, replace the brake pedal position switch.

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 CAUTION 

The vehicle must have enough air pressure to activate the brakes.

Depress the vehicle brake pedal. The multimeter must show an open circuit (100k ohms or more) when the brakes are applied. If the circuit is not open, replace the brake pedal position switch.

If the resistance value is correct, the switch must still be checked for a short circuit to ground.

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Check for Short Circuit to Ground

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Touch one multimeter probe to one of the brake pedal position switch terminals. Touch the other multimeter probe to chassis ground. Measure the resistance. The multimeter must show an open circuit (100k ohms or more) when the brake pedal is released. If the circuit is not open, replace the brake pedal position switch.

If the brake pedal position switch passed all the previous checks, connect the switch to the wiring harness. The brake pedal position switch circuit must still be checked.

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Last Modified:  03-Apr-2003

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