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Engine Controls - Pin Voltage Charts: Introduction

Pin voltage charts are supplied to reduce diagnostic time. Checking pin voltages at the Electronic Control Unit (ECU) determines whether it's receiving and transmitting proper voltage signals. Charts may also help determine if ECU harness is shorted or opened.

NOTE: ECU pin voltages for LS400 apply to 1991 models only.
NOTE: All voltage tests should be performed with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in testing procedures. Voltage readings may vary slightly due to battery condition or charging rate.
Fig 1: Identifying ECU Terminals (ES250)
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