Turn the ignition switch OFF. Turn the ignition switch ON (II). Measure voltage between the EGR valve 6P connector terminals No. 2 and No. 3. EGR VALVE 6P CONNECTOR Wire side of female terminals Is there about 5 V? YES - Go to step 13. NO - Go to step 12. Measure voltage between ECM/PCM connector terminals A10 and A20. ECM/PCM CONNECTOR A (31P) Wire side of female terminals Is there about 5 V? YES - Repair open in the wire between the EGR valve and the ECM/PCM (A10, A20). NO - Substitute a known-good ECM/PCM and recheck (see page 11-313). If symptom/indication goes away, replace the original ECM/PCM.

Turn the ignition switch OFF. At the sensor side, measure resistance between the EGR valve 6P connector terminals No. 1 and No. 2. EGR VALVE 6P CONNECTOR Terminal side of male terminals Is there continuity or resistance of 100 kohms or higher? YES - Replace the EGR valve. NO - Go to step 15. Measure resistance between the EGR valve 6P connector terminals No. 1 and No. 3. EGR VALVE 6P CONNECTOR Terminal side of male terminals Is there 100 kohms or higher? YES - Replace the EGR valve. NO - Go to step 16. Reconnect the EGR valve connector. Turn the ignition switch ON (II).