Special Tools (Diagnostic)

NOTE: In this article, diagnosis of the computerized engine control system is based on using a scan tool. Use of a scan tool saves a great deal of diagnostic time and prevents replacement of good parts. Any computer related diagnosis without a scan tool is NOT recommended.

Computerized engine control system is diagnosed using a Tech 1 or other OBD-II compatible scan tool. However, other tools are needed to aid in diagnosing problems. These tools include a tachometer (inductive pickup), a non-powered test light, digital multimeter with 10-megohm input impedance (minimum), vacuum pump and vacuum gauge, High Energy Ignition (HEI) spark tester, fuel pressure gauge, fuel injector test light (noid-light), and fused jumper wires. A test light, rather than a voltmeter, must be used when indicated by a CIRCUIT TEST procedure.