Engine Controls - Poor Heater Performance/DTC P0128
Bulletin No.: 03-06-04-065Date: December 15, 2003
TECHNICAL
Subject:
Lack of Passenger Compartment Heat and/or Raised/Rough Idle After Start and/or P0128 DTC Stored with No Service Engine Soon Light Illuminated (Reprogram ECM)
Models:
2002-2003 Chevrolet Silverado
2002-2003 GMC Sierra
with 6.6L Duramax(R) Diesel Engine (VIN 1 - RPO LB7)
Built with the Emissions shown.
Condition
Some owners may comment on the vehicle exhibiting a lack of passenger compartment heat that may be accompanied by a higher than expected or rough idle after start-up. Upon investigation, the technician may find a DTC stored but the Service Engine Soon light will not be illuminated.
Cause
The vehicle's OBD system may not be able to illuminate the Service Engine Soon light once a thermostat malfunction is detected and a P0128 DTC has been stored. The vehicle symptoms can be the result of the default actions taken by the ECM when the P0128 DTC is detected.
Correction
1. If a P0128 DTC is stored, follow the Service Manual procedures for diagnosis and repair.
2. Check to see if the 15100899, 15100900 or later updated calibration has been installed.
3. If the 15100899, 15100900 or later updated calibration has not been installed, reprogram the Engine Control Module (ECM) with TIS 2000 version 2.5 for 2003 data update or later.
Warranty Information
For vehicles repaired under the 5 year 100,000 mile Emission Warranty, use the table.
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