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Home >> Chevrolet >> 2002 >> TrailBlazer RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 377 (ENGINE CONTROLS - SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L - Flex Fuel & Gasoline) >> Diagnostic Tests >> DTC P1518: TAC Module Serial Data Fault >> Test Description

Test Description

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The numbers below refer to the step numbers in the diagnostic procedure.

  1. 2

    This step determines if the IGN relay is supplying a voltage to the ETC fuse.

  2. 5

    Increasing the engine speed to 3000 RPM aids in locating a shorted throttle actuator motor control circuit. Depending on the polarity of the throttle actuator motor transistors, this DTC may not set with a fault in the control circuits. The throttle actuator motor is a bi-directional DC motor. Raising the engine speed changes the polarity of the transistors in the throttle actuator motor. This occurs because 1 set of the transistors are low, 0 volts, and the other set are high, battery voltage. Therefore, if 1 set of transistors are at a low voltage and the corresponding circuit is shorted low, DTC P1518 will not set. When the polarity of the transistors change this DTC sets. If this DTC does not Fail This ignition, continue to monitor this DTC status while moving related harnesses and connectors.

  3. 29

    Locating and repairing an individual condition may correct more than 1 DTC.
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