Engine Controls - Pin Voltage Charts: Introduction

Pin voltage charts are supplied to reduce diagnostic time. By checking pin voltages at the Electronic Control Module (ECM), it is possible to determine if the ECM is receiving and transmitting proper voltage signals. Charts may also help determine if ECM harness has shorts or opens.

NOTE: Unless stated otherwise in testing procedures, perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance. Voltage readings may vary slightly due to battery condition or charging rate.

NOTE: The following conditions must be met before testing.

Engine is at operating temperature.
Engine is at idle in closed loop operating mode (engine running tests).
ALDL diagnostic connector is NOT grounded.
Scan tester is NOT installed.