Intermittent Diagnostics

NOTE: Intermittent issues may or may not turn ON the check engine light or store Diagnostic Trouble Codes (DTC).

Checks	Action
Preliminary Checks	Do not use the DTC table. If a fault is an intermittent, the use of the DTC tables with this condition may result in the replacement of good part
Faulty Electrical Connection & Wiring	Faulty electrical connections or wiring can cause most intermittent problems. Check the suspected circuit for the following conditions: - Faulty fuse or circuit breaker, connectors poorly mated, terminals not fully seated in the connector (backed out). Terminals not properly formed or damaged - Terminal tension is insufficient - Wire terminals poorly connected - Examine any and all potential terminals for proper contact tension
Operational Test	Once all visual and physical examination does not locate the problem, operate the vehicle with VCM live on any watch any abnormal spikes in voltage with the corresponding parameter
Loss of DTC Memory	To Check for the loss of DTC memory check the following: 1. Disconnect any sensor 2. Idle the engine until the check engine light illuminates 3. VCM Live should store a DTC for whichever sensor was disconnected and remain in the memory when the ignition is turned OFF. If no DTC is stored, the ECU might be faulty.

Table 57. Intermittent Diagnostics Table