C 3500 Truck 2WD V8-454 7.4L VIN J SFI (1999)
PROM - Programmable Read Only Memory: Customer Interest
PCM - MIL ON/DTC P0446 EVAP System Malfunction
File In Section: 06 - Engine/Propulsion System
Bulletin No.: 00-06-04-042
Date: October, 2000
TECHNICAL
Subject:
Malfunction Indicator Lamp (MIL) On With DTC P0446 Code Set
(Reprogram PCM)
Models:
1998-2000 Chevrolet and GMC C/K Models
with 7.4 L Engine (VIN J - RPO L29) and California Emissions (NB6)
Condition
Some customers may comment on a Malfunction Indicator Lamp (MIL) that is illuminated. Further investigation will find a DTC P0446 code has been
set.
Cause
The code is more likely to occur with less than 1/2 tank of fuel. The VCM monitors the performance of the EVAP system by applying a predetermined
level of vacuum to the EVAP system. The VCM then monitors the vacuum decay rate. The VCM sets this DTC if the vacuum decay rate is greater than a
predetermined value. The decay rate at idle is higher than the monitoring portion of the current calibration range will allow.
Correction
Once the vent solenoid is verified to be operational, reprogram the vehicle with a new calibration.
Parts Information
The calibrations listed are electronic calibrations and are NOT available from GMSPO. Calibrations will be available from Techline starting on the TIS
2000 CD 13 shipped to dealers 7/6/00.
Warranty Information
For vehicles repaired under warranty, use the table.
Disclaimer
