Engine Controls - Idle Speed Control Learn Procedure
T-SB-0316-09September 3, 2009
ISC Learning Procedure
Service Category
General
Section
Pre-Delivery Service
Market
USA
Applicability
Introduction
When the 12-volt battery is disconnected or is depleted below 7 volts on 2010 model year Highlander HV vehicles it is necessary to perform the ISC Learning procedure to re-initialize the idle speed control. The information in this TSB describes this procedure.
Required Tools & Equipment
Additional TIS Techstream units may be ordered by calling Approved Dealer Equipment (ADE).
Warranty Information
ISC Learning Procedure
It is important to perform the ISC Learning procedure anytime the 12-volt battery is disconnected or the voltage falls below 7 volts. This procedure allows the internal combustion engine to relearn its optimal idle speed during the initial engine warm-up cycle or charging the HV battery. If this procedure is NOT performed, the following customer complaints may occur:
^ Engine runs too long or more frequently than normal
^ Reduced fuel economy
^ Transmission gear "clatter" noise at idle is more pronounced
In TIS Techstream, the current state of ISC Learning status can be accessed through the following path:
Powertrain/Engine/Data List/ISC Learning
ISC Learning value identifies the current status of ISC Learning and is expressed as either "COMPL (complete) or "INCOMP" (incomplete).
Each time the ignition is cycled to the "OFF" position, the ISC Learning value will show "INCOMP" until the engine completes its initial startup/shutdown. The following procedure should be used to verify the current status of the ISC Learning:
1. Drive the vehicle until the engine reaches operating temperature 158°F (70°C). It can be accessed through TIS Techstream:
Powertrain/Engine/Data List/Coolant Temp
2. Park the vehicle and cycle the ignition OFF.
3. Access the ISC LEARNING data parameter:
Powertrain/Engine/Data List/ISC Learning
4. Cycle the "POWER" switch back to "READY ON".
5. Wait for the engine to start and run through its initial startup cycle and shut OFF.
6. Observe the ISC Learning status.
If the vehicle shows "INCOMP" after initial engine shutdown in step 5, then the ISC Initialization Procedure should be performed.
ISC Initialization Procedure
1. Connect TIS Techstream to the vehicle.
2. Select the following menu items:
Powertrain/Engine/Data List/Coolant Temp
3. Check that the engine coolant temperature is 181°F (83°C) or more.
HINT
If the engine coolant temperature is below 181°F (83°C), start the engine by depressing the accelerator pedal with the shift lever in the "P" position to increase the coolant temperature.
4. Select the following menu items:
Powertrain/Hybrid Control/Data List/Calculate Load
5. Move the shift lever to the "D" position while depressing the brake pedal with the LEFT foot.
6. Depress the accelerator pedal with the right foot while firmly depressing the brake pedal with the left foot, and maintain an engine load value of 45% or more (60 - 70% of full acceleration) for approximately 30 seconds.
NOTE
Do NOT perform this step for more than 40 seconds.
7. Shift the lever to the "P" position. Cycle the "POWER" switch OFF and then wait for 5 seconds before putting the vehicle into the "READY ON" state again.
8. Select the following menu items:
Powertrain/Engine/Data List/ISC Learning
9. Check that the air conditioner is OFF. Lightly depress the accelerator pedal and release it when the engine starts.
10. Check that "COMPLETE" is displayed on the TIS Techstream screen.
HINT
^ If "ISC LEARNING" is NOT completed within 1 minute, repeat steps 4 - 8.
^ The engine will usually stop when the "ISC LEARNING" is completed. However, the engine will NOT stop even when the "ISC LEARNING" is completed if the state-of-charge of the auxiliary battery is low.