| Subject: | DTC U1000, U1016, U1040, U1064, U1096 or U1305 Set in Error |
| Models: | 2004 Pontiac Grand Prix |
This bulletin is being revised to add DTC U1040 to the bulletin information.
Please discard Corporate Bulletin Number 03-08-116-001 (Section 08 - Body and
Accessories).
When servicing the above listed vehicle for any concern that requires the use
of the Tech 2® Diagnostic Scan Tool, you may find one or more "U"
codes. These codes may be present due to a communication error in the software that
results in multiple data link messages being sent at the same time. Whenever this
occurs, the receiving module may set a communication fault code. Known codes that
have been erroneously set are:
| • | U1000 -- General Communication Fault |
| • | U1016 -- Loss of Communications with PCM |
| • | U1040 -- Loss of Communications with EBCM |
| • | U1064 -- Loss of Communications with BCM |
| • | U1096 -- Loss of Communications with the IPC |
| • | U1305 -- Data Line Short to Batt/GND |
Actions to Take
Important: Do not attempt any repairs on the vehicle
based on these codes. There is no corrective action that will prevent the reoccurrence
of these codes at this time.
First, you must verify that you have communication capability with the affected
module. Using the Diagnostic Scan Tool, establish communication with the affected
modules. If communication can be established, U1000, U1016, U1040, U1064, U1096, or
U1305 can be ignored and cleared from history. Do not attempt any repairs on the vehicle
based on these codes. There is no corrective action that will prevent the reoccurrence
of these codes at this time.
If a U1000 code is found to be current and/or you experience trouble establishing
communications with any of the affected modules called out by other DTCs, refer to
the 2004 Grand Prix Service Information diagnostic tables for proper diagnostics.
