Test 12: Pressure Switch Problem

Turn ignition off. Disconnect pressure switch 2-pin connector (White/Green wire and Red/Black wire) at hydraulic unit. Measure resistance between pressure switch terminals at hydraulic unit. With brake pedal depressed, resistance should be infinite. With brake pedal released, resistance should be one ohm or less. If resistance is as specified, go to next step. If resistance is not as specified, replace hydraulic unit.
Measure resistance between ground and each terminal of pressure switch 2-pin connector at hydraulic unit. If both resistance readings are infinite, go to next step. If either resistance reading is not infinite, replace hydraulic unit.
Reconnect hydraulic unit connector. Disconnect ABS/TCS control unit connectors. Measure resistance between terminals No. 6 and 18 at ABS/TCS control unit 20-pin harness connector. See Figure . With brake pedal depressed, resistance should be infinite. With brake pedal released, resistance should be less than one ohm. If resistance is as specified, go to next step. If resistance is not as specified, repair wiring harness as necessary.
Measure resistance between ground and terminals No. 6 and 18 at ABS/TCS control unit 20-pin harness connector. If both resistance readings are infinite, go to next step. If either resistance reading is not infinite, repair wiring harness as necessary.

Remove stroke sensor/brakelight switch. With stroke sensor/brakelight switch rod at specified position, measure resistance between terminals No. 2 and 3 at brakelight switch connector. See BRAKELIGHT SWITCH RESISTANCE SPECIFICATIONS table. See Figure . Replace stroke sensor/brakelight switch as necessary. If switch is okay, go to next step.

BRAKELIGHT SWITCH RESISTANCE SPECIFICATIONS

Stroke Length In. (mm) ⁽¹⁾

Ohms

0-.13 (0-3.2)

Infinite

.05-.73 (1.2-18.5)

1 Or Less

⁽¹⁾	Measure distance between end of stroke sensor/brakelight switch housing and end of stroke sensor/brakelight switch rod. See Figure .

Measure resistance between stroke sensor/brakelight switch threaded part of housing and terminals No. 2 and 3 at brakelight switch connector. If both resistance readings are infinite, go to next step. If any resistance reading is not infinite, replace stroke sensor/brakelight switch.
Measure voltage between ground and terminal No. 3 at brakelight switch connector. If battery voltage exists, go to next step. If battery voltage does not exist, repair wiring harness as necessary.
Reinstall stroke sensor/brakelight switch and connectors. Disconnect ABS/TCS control unit connectors. Measure voltage between ground and terminal No. 7 at ABS/TCS control unit 20-pin harness connector. See Figure . With brake pedal depressed, battery voltage should be present. With brake pedal released, voltage should be zero volts. If voltage is as specified, replace ABS/TCS control unit. If voltage is not as specified, repair wiring harness as necessary.