Express 1/2 Ton Van V8-305 5.0L VIN M SFI (1998)
EGR Valve: Technical Service Bulletins
DTC P1404 (False Low EGR Valve Pintle Position) Signals
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 86-65-03A
Date: September, 1998
Subject:
OBD II Diagnostic Trouble Code (DTC) P1404 (Reflash VCM)
Models:
1998-*99 Chevrolet and GMC C/K, M/L, S/T**, G, P Models
1998 Oldsmobile Bravada with 4.3L, 5.0L, 5.7L or 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)
This bulletin Is being revised to correct Application information for calibration P/N's 09364726 and 09364733. Please discard Corporate Bulletin
Number 86-65-03 (Section 6E - Engine Fuel & Emission).
Condition
Some vehicles may set a false OBD II DTC P1404.
Cause
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 P14O4 DTC because the VCM perceives that the EGR valve is stuck open.
Correction
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 listed below. These new calibrations are designed to make the
DTC less susceptible to noise.
