| Subject: | Information on ReSetting the Battery Light If It Remains Illuminated After
PCM Replacement |
| Models: | 2005 Cadillac Escalade |
| 2005 Chevrolet Avalanche, Silverado
1500 Series, Suburban, Tahoe |
| 2005 GMC Denali, Sierra 1500 Series, Sierra Denali, Yukon XL |
| with Regulated Voltage Control (RVC) Module |
This bulletin is being revised to include additional information on the IPC/RVC
module. Please discard Corporate Bulletin Number 05-08-49-010 (Section 08 --
Body and Accessories).
After successfully reprogramming a service Powertrain Control Module (PCM) with
Regulated Voltage Control (RVC) module, the technician may find the battery light
is illuminated even after multiple ignition cycles.
The instrument panel cluster (IPC) receives a battery light request
from the RVC module, not the PCM. The PCM for the above-mentioned vehicles for model
year 2005 may contain old PCM software that sends a Class2 message (Alternator Lamp)
to the IPC. If the IPC receives a message, the IPC learns that the PCM sent the message
and expects the PCM to always send the message. If the IPC does not receive the message
from the PCM, the battery light will illuminate. Once the service PCM is programmed
with latest model year 2005 software, the PCM will never send this Class2 message
again.
Temporarily remove all electrical power to the IPC. This will reset the battery
light within the IPC. This can be accomplished by one of the following methods.
| • | Remove the IPC/DIC fuse from the Underhood Fuse Block for approximately
30 seconds. Refer to the diagram for the location of the fuse. |
| • | Disconnect the Positive Battery terminal for approximately 30 seconds
and then reconnect. If this method is used, make sure to save all preset memory functions
on all vehicle options/accessories. |
