MIL ON - DTC P0400 (EGR Flow)/Stalls/Rough Idle

Classification:
EC97-039

Reference:
NTB97-100

Date:
January 15, 1998

1996-97 TRUCK ROUGH/NO IDLE AND/OR DTC P0400 STORED IN THE ECM DUE TO EGR VALVE STICKING

APPLIED VEHICLE:
All 1996-97 Truck (D21)

SERVICE INFORMATION

Use this bulletin if a 1996-97 Truck will not maintain idle or idles roughly after an engine cold soak and/or the MIL is "on" with DTC P0400 stored in the ECM.

A countermeasure EGR valve is available to resolve such incidents if the cause is a sticking EGR valve.

SERVICE PROCEDURE

With the engine cold, perform an inspection of the EGR valve as follows:





1. Apply vacuum to the EGR valve with a hand vacuum pump, then release the vacuum (see Figure 1).

2. Check to see that the EGR valve opens when the vacuum is applied and closes when the vacuum is released.

A. If the EGR valve sticks open or does not open and close smoothly, replace the EGR valve with the countermeasure EGR valve and gasket.

B. If the EGR valve opens and closes smoothly, refer to Trouble Diagnosis in the EC section of the appropriate service manual to diagnose this incident.





PARTS INFORMATION

CLAIMS INFORMATION
When applicable, standard claims coding applies.