Diagnostic Notes

BEFORE STARTING

1. Verify customer complaint and locate correct symptoms.


2. Several symptom procedures call for a careful visual check. The importance of this step cannot be stressed too strongly - it can lead to correcting a problem without further checks and can save valuable time. Visually Inspect:

- Vacuum hoses for splits, kinks, and proper connections, as shown on Emission Control Information label.
- Air leaks at throttle valve mounting, common chamber mounting and intake manifold.
- Ignition wires for cracking, harness, proper routing, and carbon tracking.
- Wiring for proper connections, pinches, and cuts.

3. Be careful when checking system components (Closed Loop Emission Control System), especially when handling electrical parts, ECM etc..

When checking Engine Control Module (ECM) harness connector terminals from connector wire side with tester probe, be careful not to touch other terminal by mistake. Do not insert circuit tester test probes into connector open side to test continuity.

Before starting with a voltmeter connected to a suspected circuit, check to see if battery is in fully charged condition.

Before disconnecting ECM connectors, be sure ignition switch is "OFF"; check and record codes stored in ECM memory. When disconnecting ECM connectors, all three connectors should be removed (all stored codes will be cleared when this is done). When connecting a suspected circuit to Battery + terminal or Engine ground, it will be advisable to install a test light (3.2W, 12V) in between, to protect electronic parts from being damaged.