Check For Intermittent Problems

HINT:

Intelligent tester only:

Inspect the vehicle's ECM using check mode. Intermittent problems are easier to detect with a 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 DTCs (see  DTC CHECK / CLEAR  ). 
2. Switch the ECM from normal mode to check mode using a 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  HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS  ).