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Home >> Isuzu >> 2003 >> Ascender 5.3 P, RWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 5.3L >> Diagnostic Tests >> DTC P1518: Throttle Actuator Control Module Serial Data Fault >> Test Description

Test Description

The numbers listed below refer to 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 one set of the transistors are low, zero volts, and the other set are high, battery voltage. Therefore, if one 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 one DTC.

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