Check For Intermittent Problems

HINT:

Intelligent tester only:

Inspect the vehicle's ECM using check mode. Intermittent problems are easier to detect with an intelligent tester when the ECM is in check mode. In check mode, the ECM uses 1 trip detection logic, which is more sensitive to malfunctions than normal mode (default), which uses 2 trip detection logic.

1. Clear the DTCs (See  DTC CHECK / CLEAR   ). 
2. Switch the ECM from normal mode to check mode using an intelligent tester (See  CHECK MODE PROCEDURE  ).
3. Perform a simulation test (See  HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS  ). 
4. Check and wiggle the harnesses, connectors and terminals (See  ELECTRONIC CIRCUIT INSPECTION PROCEDURE  ).