Hope this help
ENG OBD II DTC P1404 - REFLASH VCM
TECHNICAL SERVICE BULLETIN
Reference Number(s): 86-65-03, Date of Issue: July, 1998 Related Ref Number(s): 86-65-03
OBD II DIAGNOSTIC TROUBLE CODE (DTC) P1404 (REFLASH VCM)
Model(s): 1998* -99 Chevrolet and GMC C/K, M/L, S/T**, G, P Models with 4.3L, 5.0L, 5.7L, 7.4L Engine (VINs X, W, M, R, J - RPOs LF6, L35, L30, L31, L29)
* (C/K, G with RPO ZK3) ** (Does not include RPO ZN4)
1998 Oldsmobile Bravada with 4.3L, 5.0L, 5.7L, 7.4L Engine (VINs X, W, M, R, J - RPOs LF6, L35, L30, L31, L29)
Section: 6E - Engine Fuel & Emission
Bulletin No: 86-65-03
Date: July, 1998
Some vehicles may set a false OBD II DTC P1404.
Electronic noise in the vehicle may create momentary false "low" exhaust gas recirculation (EGR) pintle position feedback signal values. Severe occurrences may cause the vehicle control module (VCM) to set a P1404 DTC because the VCM perceives that the EGR valve is stuck open.
1. Using the Tech 2 Scan Tool, exercise the EGR valve and verify the valve's actual and desired position track. 2. Following steps 1, 2 and 3 of the Strategy Based Diagnostics, determine if the vehicle has an actual EGR valve condition. If there is a valve condition, perform the appropriate repair procedures. 3. Finally, reflash the VCM with the new software and corresponding calibrations
Saturday, March 28th, 2009 AT 8:17 PM