1994 Chevrolet 2500 Trouble codes.
I have a 94 Chevy 2500, it flashes error 3 across the dummy screen with the truck mileage. I hooked it up to a diagnostic code reader, I got the following codes:
DTC 12 -
When terminals "A" and "B" have been connected, the ignition switch
turned to the "ON" position with the engine not operating, the MIL
(Service Engine Soon) should flash DTC 12 three times consequently. This
will be the following flash sequence: "flash, pause, flash-flash,
pause, flash, pause, flash-flash, pause, flash, pause, flash-flash." DTC
12 indicates that the control module diagnostic system is operating
properly. If DTC 12 is not indicated, and a fault is present within the
diagnostic system itself, it should be addresses by consulting the
appropriate diagnostic chart in this section.
The MIL (SES) will indicate a diagnostic trouble code (DTC) three times
if a DTC is present, or it will simply continue to output DTC 12. If
more than one DTC has been stored in the control module memory, the
DTC(s) will be displayed from the lowest to the highest with each DTC
being displayed three times.
DTC 32 - Exhaust Gas Recirculation (EGR) Error
EGR open command did not change the fuel mixture when the command
was given during off idle operation. EGR opening should cause
to be slightly richer because of the low oxygen content of the
gas. EGR position signal is also monitored to verify EGR
The EGR relies on a certain amount of
exhaust back pressure to work properly. Now that you have lowered the
back pressure, it can't work. Have you tried a new EGR valve? You may
need a service manual with an EGR diagnostic chart to make sure, but I
think the duals are the problem. Plus the O2 sensor is only looking at
one side of engine instead of both.
Keep in midn this procedure to Clearing Diagnostic Trouble Codes:
To clear the DTC's from memory of the control module, either to
determine if the malfunction will occur again or because the repair has
been completed, the Tech 1 Scan Tool should be used to clear the DTC's.
If a Tech 1 Scan Tool is not available the following must be perform'd
when all repairs have been completed. This will allow all DTC's to be
1. Ignition "OFF."
2. Ground diagnostic terminal "A" to "B" of DLC (Data Link Connector).
3. Ignition "ON."
4. Fully apply brake pedal.
5.Fully apply accelerator pedal.
6. Check MIL (Service Engine Soon) for DTC 12.
7. Release brake pedal.
8. Release accelerator pedal.
9. Check MIL (Service Engine Soon) for DTC 12.
10. Turn ignition
11. Remove Jumper from DLC connector.
NOTICE: To prevent control module damage, the key must be "OFF" when
disconnecting or reconnecting module power.
Jun 30, 2010 |
Chevrolet C3500 Cars & Trucks