Pin Voltage Charts: Introduction

PIN VOLTAGE CHARTS are supplied (where available) to speed up the diagnostic process. By checking pin voltages at the electronic control unit, it is possible to determine if the control unit is receiving and transmitting proper voltage signals. Charts may also help determine if control unit harness has shorts or opens.

NOTE: When testing pin voltages, it is recommended that a DVOM with high input impedance be used in order to ensure accurate voltage readings.

NOTE: This ECM voltage chart may be used with a digital voltmeter to help save diagnostic time. Voltage readings on the vehicle being tested may vary slightly due to battery condition or charge rate.

NOTE: The following conditions must be met before testing:

Engine at operating temperature.
At idle in "closed loop" operating mode (engine running tests).
ALDL "Test" terminal NOT grounded.
Scan" tester NOT installed.