| Subject: | Revised Diagnostic Trouble Codes (DTCs) P0404, P0405,
P1404 |
| Models: | 1998-2000 Chevrolet and GMC C/K, G, M/L, S/T Models |
| 1998-1999 Chevrolet and GMC P32/P42 Models |
| 1999 Chevrolet and GMC P12 Models |
| 1999-2000 Chevrolet and GMC B7 School Bus and C6-7 Conventional Medium
Duty Models |
| 1999-2000 Chevrolet and GMC S/T RHD Models |
| 1999-2000 Isuzu S/T Models |
| 1999-2000 Cadillac Escalade |
| 1998-2000 Oldsmobile Bravada |
| with 4.3L, 4.8L, 5.0L, 5.3L, 5.7L, 6.0L 7.4L or Engine (VINs W, X, V,
M, T, R, U, J -- RPOs L35, LF6, LR4, L30, LM7 , L31, LQ4, L29) |
This bulletin is being issued to revise DTCs P0404, P0405 and P1404
in the following Engine Controls sub-sections of the above-mentioned Service
Manuals:
| • | Engine Controls - 4.8L, 5.3L, 6.0L |
| • | Engine Controls - 5.0L, 5.7L |
Please replace the current information in the Service Manuals with the
following information.
The following information has been updated within SI2000. If you are
using a paper version of any of these Service Manuals, please make a reference
to this bulletin on the affected pages.
In order to properly test the EGR High Control circuit for voltage,
THE ENGINE MUST BE RUNNING when using a scan tool to command the EGR valve
ON. This procedure will apply to various steps in the DTC tables mentioned
above. Refer to the example below for the correct procedure.
- Turn OFF the ignition.
- Disconnect the EGR valve harness connector.
- Connect a test lamp between the EGR valve high control circuit
at the EGR valve harness connector and a known good ground.
- START THE ENGINE.
- With a scan tool, command the EGR valve to 50%.
Does the test lamp illuminate when commanding the EGR valve on?
