Fast Idle

UI BULLETIN # 82 SUBJECT: Fast Idle — RPO UF3 MODELS AFFECTED: C/K 2500HD / 3500HD / 3500HD Chassis Cab, Chevrolet Silverado and GMC Sierra & G/H Cargo and Cutaway Van, Chevrolet Express and GMC Savana ENGINE OPTIONS: 6.0L (LY6) Gas and 6.6L (LMM) Diesel MODEL YEAR(S): 2008 DATE: 11/01/2007

ADVISORY This bulletin provides a description of the Fast Idle (UF3) option on 2008 C/K 2500HD / 3500HD / 3500HD Chassis Cab and 2008 G/H Cargo / Cutaway Van models. To obtain Fast Idle capability on 2008 vehicles, you must order: C/K Full Size Truck

1. C/K 2500HD / 3500HD / 3500HD Chassis Cab (Fast Idle is not available on 1500 models) 2. 6.0L (LY6) gas engine or 6.6L (LMM) diesel engine 3. Cruise Control – RPO K34 4. Fast Idle – RPO UF3 G/H Full Size Van 1. G/H Cargo / Cutaway Van – (Fast Idle is not available on Passenger, Cargo w/YF7, or Cargo/Mobility models) 2. 6.6L (LMM) diesel engine (Fast Idle is not available with 6.0L (LY6) gas engine) 3. Cruise Control – RPO K34 4. Fast Idle – RPO UF3



Fast Idle (RPO: UF3) must be ordered and cannot be retrofitted.

TABLE OF CONTENTS 1. SYSTEM OVERVIEW.......................... 2 3. FUNCTIONAL DESCRIPTION (cont’d)

1.1. FAST IDLE OVERVIEW............................... 2

2. COMPONENT LOCATION................... 2

2.1. FAST IDLE CONTROLS LOCATION............ 2

3. FUNCTIONAL DESCRIPTION.............. 3

3.1. REQUIRED INITIAL CONDITIONS................ 3 3.2. ENABLE (turn on) FAST IDLE........................ 3 3.3. PRESET FAST IDLE....................................... 3



3.4. VARIABLE FAST IDLE.................................... 3 3.5. DISABLE (turn off) ACTIONS. .................... 4

4. DIC STATUS MESSAGES.................... 4

4.1. DIC WILL DISPLAY “FAST IDLE ACTIVE”.... 4

5. FAST IDLE SUMMARY. ...................... 5

Notes: This bulletin addresses the “All New,” not the “Classic” C/K Truck. Bulletin 82–Rev. 11/2007 11/01/2007  of 5

UI BULLETIN # 82 (Cont.) 1. SYSTEM OVERVIEW

1.1. Fast Idle System Overview

IPC

LS GMLAN

HS GMLAN

BCM

ECM

Max Fast Idle RPM Calibration

DIC FAST IDLE ON

Fast Idle Mode Active

Engine Speed Request

CRUISE SWITCH

2. COMPONENT LOCATION

2.1. Fast Idle Controls Location

Fast Idle is controlled using the Cruise Control buttons located on the left-hand side of the steering wheel.

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UI BULLETIN # 82 (Cont.) 3. FUNCTIONAL DESCRIPTION

3.1. Required Initial Conditions These conditions must be met for Fast Idle to work: o o o o

Park Brake must be set Transmission/PRNDL must be in Park (P) or Neutral (N). The Brake must not be pressed. Vehicle Speed must be zero.

3.2. Enable (turn on) Fast idle o After the Required Initial Conditions (see 3.1) have been met, you can Enable Fast Idle by pressing and releasing the Cruise Control “ON” switch, the LED indicator on the switch will illuminate.



3.3. Preset Fast Idle o After the Required Enable Conditions (see 3.2) have been met, you can Preset Fast Idle by pressing and releasing the Cruise Control “SET” switch to achieve the preset Note: Preset Fast Idle Speed of 1,250 RPM is NOT adjustable via Tech II.

3.4. Variable Fast Idle o After the Required Enable Conditions (see 3.2) have been met, you can set Variable Fast Idle by Depressing and Holding the accelerator at the desired RPM, then Pressing and Releasing the Cruise “SET” switch to establish the desired Fast Idle speed. The Variable Fast Idle speed can be observed on the tachometer. Note: Variable Fast Idle is NOT remembered after an Ignition Cycle. Bulletin 82–Rev. 11/2007 11/01/2007  of 5

UI BULLETIN # 82 (Cont.) 3. FUNCTIONAL DESCRIPTION (cont’d)

3.5. Disable (turn off) Actions Any of these conditions will cancel Fast Idle: o o o o o o

Turn Cruise Off. Press and Release the Cruise Control “ON/OFF” switch. The LED indicator will turn off. Press and Release the Cruise Control “SET” switch Press the brake pedal. Press and Release the Cruise Control “CANCEL” switch. Release the Park Brake. Move the Transmission Shift Lever (PRNDL) from Park (P) or Neutral (N).

Note: Vehicle motion will cancel Fast Idle.

4. DRIVER INFORMATION CENTER (DIC) STATUS MESSAGES

4.1. Driver Information Center (DIC)

The DIC will display “FAST IDLE ACTIVE” when Fast Idle is engaged.

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UI BULLETIN # 82 (Cont.) 5. FAST IDLE SUMMARY Product

Fast Idle Default Speed (RPM)

G/H Van

1200 (LMM Diesel only)

C/K Truck

Fast Idle Max Speed (RPM)

Fast Idle Speed Adjustability*

Fast Idle Active Display

Driver Information 1200 Single Speed Only Center (LMM Diesel only) (if equipped)

1250 (LMM Diesel) 1300 (LMM Diesel) 1000 (LY6 Gas) 1000 (LY6 Gas)

Accelerator Pedal & Cruise Control SET Button Only

Driver Information Center (if equipped)

* No Tech II Speed adjustment possible

Bulletin 82–Rev. 11/2007 11/01/2007  of 5