Road Test

The following tests should be performed with 2 people to ensure the safe operation of the vehicle.

• Drive vehicle while monitoring the suspect circuit with a scan tool or a DMM connected to the circuit. Look for an abnormal reading or voltage when malfunction occurs. An abnormal reading on the scan tool or an abnormal voltage on DMM display is an indication that there may be a malfunction in the circuit being monitored.
• If the intermittent fault sets a DTC, the diagnostic that sets the DTC can be enhanced using CHECK MODE. Operating vehicle while in check mode can enable certain DTC diagnostics to run faster. Check mode also turns some "B" type DTCs to "A" type DTCs. See SERVICE BAY TESTS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 1.8L VIBE article.
• Certain DTCs must run before I/M system status can be determined. Any DTC that affects the status of an I/M system can be monitored indirectly on the scan tool under the I/M System Information selection. To determine which DTCs are associated with a particular I/M system test, see INSPECTION/MAINTENANCE SYSTEM DTCS under DRIVE CYCLES in SELF-DIAGNOSTICS - 1.8L VIBE article. If an intermittent DTC is associated with a particular I/M system, monitoring the I/M system test can indicate whether the diagnostic for that DTC has run. When I/M system test displays a YES status, indicating system diagnostic is complete, check for applicable DTC in LAST TEST FAILED screen of the scan tool. If the DTC is not displayed, diagnostic for that DTC has run and passed, indicating that no malfunction was present this time. All DTCs MUST BE CLEARED to view CURRENT STATUS of I/M system tests. Do not forget I/M System Information tests only indicate the test has run, not if the test passed or failed. The LAST TEST FAILED screen must be checked for related DTCs to determine the outcome of the diagnostic test involved.