The PCM is designed to withstand normal current draws associated with vehicle operations.
Avoid overloading any circuit. When testing for opens or shorts, do not ground any of the PCM
circuits unless instructed. When testing for opens or shorts, do not apply voltage to any of the
PCM circuits unless instructed. Only test these circuits with a DMM while the PCM connectors
remain connected.
PROCEDURE
A Tech II or equivalent Scan tool must be used to check or clear Diagnostic Trouble Codes
(DTCs) from the PCM memory. When clearing DTCs, follow the instructions supplied by the
Scan tool manufacturer.
NOTES: Do not clear the DTCs unless directed to do so by the service information provided
for each diagnostic procedure. All of the diagnostic data that was saved along with the DTC
(freeze frame data and/or malfunction history records) which may be helpful for some
diagnostic procedures will be erased from the memory when the DTCs are cleared.
Interrupting PCM battery voltage to clear DTCs is NOT recommended and will not turn off the
check engine light.
Once a DTC has been identified, contact the Painless tech dept. or a GM Service
Manual for a procedure to identify why a particular code is being set. Do not
assume a code for a component is the result of the component being faulting and
its replacement will solve the reason for the code. This could result in unnecessary
replacement of functioning components.
7.3 IDLE LEARN PROCEDURE
Anytime the Powertrain Control Module (PCM) or the battery is disconnected, the PCM loses
power, or the PCM is reprogrammed, the PCMs learned idle position is lost. The engine idle is
unstable when the learned idle position is lost. Perform the following procedure in order to
return the learned idle to the correct position:
7.3.1 AUTOMATIC TRANSMISSION
1.
Turn OFF the ignition.
2.
Restore the PCM battery feed.
3.
Turn OFF the A/C controls.
4.
Set the parking brake and block the drive wheels.
5.
Start the engine.
6.
Ensure that the engine coolant temperature is more than 80°C (176°F).
7.
Shift the transmission into Drive.
8.
Allow the engine to idle for 5 minutes.
9.
Shift the transmission into Park.
10.
Allow the engine to idle for 5 minutes.
11.
Turn OFF the engine for 30 seconds.
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