PCM - Adapting to Varying A/C Loads
Group: ENGINE ELECTRICALNumber: 01-36-005
Date: APRIL, 2001
Model: 2001 XG300
Subject:
2001 XG300 PCM ADAPTATION FOR VARYING A/C LOADS TO PREVENT ENGINE SURGING
DESCRIPTION:
This TSB describes how to "teach" the powertrain control module (PCM) to adapt to varying A/C Loads.
This procedure is required whenever:
1. The PCM has experienced an interuption of power (battery disconnected)
2. The PCM has been reprogrammed, or
3. The PCM has been cleared using the Hi-Scan Pro.
If this procedure is not carried out, the customer may notice an engine "surging" when the A/C compressor engages and dis-engages.
PROCEDURE:
1. Warm-up the engine. The coolant temperature must be above 167°F (75°C) before the PCM learning function becomes active.
2. With the transmission in Park, turn on the A/C. The engine speed will increase (about 1000 to 1500 rpm), then decrease back to normal.
3. Allow the engine to idle for 10 minutes.
4. Turn the engine off. Wail 10 seconds (for the PCM relay to de-energize). Restart the engine and confirm the engine does not surge when the A/C is turned on. If it still surges, repeat steps 1-3.
5. Final, drive the vehicle with the A/C on. The engine should not surge when the A/C compressor engages. If it does, repeat steps 1-3.