Engine Controls - Pin Voltage Charts: Introduction

Pin voltage charts are supplied (where available) to reduce diagnostic time. Checking pin voltages at the electronic control unit determines whether the control unit is receiving and transmitting proper voltage signals. Charts may also help determine if control unit harness has shorts or opens.

NOTE: Use T-100 Yellow Breakout Box (48921) to obtain pin voltage reading from each circuit. Ensure DVOM negative lead is connected to a known good ground. this ECM voltage chart can be used with a digital voltmeter to save time in diagnosis. Voltages on vehicle being tested may vary slightly from these due to battery voltage or alternator charging level.

Following conditions must be met before testing:

Engine at operating temperature.
Engine in closed loop operation.
Engine idling (ENG. RUN column).
ALDL "test" terminal not grounded.
Scan tester not installed.