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ECU Power Circuits

  1. Turn ignition switch to the "ON" position. Connect negative lead of DVOM to a good ground. Check for voltage on terminals No. 25 (while depressing brake pedal), 27, 28 and 29 of ECU connector. All terminals should have battery voltage present except for terminal No. 29. Terminal No. 29 should have .5 - 1 volt. 2)If there is no voltage present at terminals Nos.
    • 25 - Check brake light switch, replace if defective.
    • 27 - Replace defective solenoid relay.
    • 28 - Replace defective pump relay.
    • 29 - If voltage reading at terminal No. 27 is correct, voltage at terminal No. 29 should be .5 - 1.0 volt. If voltage at terminal No. 29 is not correct, replace solenoid relay.
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