GM Service Manual Online
For 1990-2009 cars only

Engine Control Module (ECM) 6.6L (LBZ)/(LLY)

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

Operating Conditions: Ignition ON/Engine Running

Clutch Pedal Switch

Engine 1

Applied / Released

Released

GEN L-Terminal Signal

Engine 1

Voltage / No Voltage

NO Voltage

Ignition 1 Signal

Engine 1

Volts

Varies

PNP Switch

Engine 1

In Gear / Park / Neutral

Park / Neutral

Stop Lamp Pedal Switch

Engine 1

Applied / Released

Released

Engine Control Module (ECM) 6.6L (LMM)

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

Operating Conditions: Ignition ON/Engine Running

Crank Request Signal

Engine

Yes / NO

NO

GEN F-Terminal Signal

Engine

%

Varies

GEN L-Terminal Signal Command

Engine

ON / OFF

ON

Ignition 1 Signal

Engine

Volts

Varies

PNP Switch

Engine

Park / Neutral / In Gear

Park

Starter Relay Command

Engine

ON / OFF

OFF

Engine Control Module (ECM) 7.8L (LG4)

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

Operating Conditions: Ignition ON/Engine Running

Battery Voltage

Engine 1

Volts

Varies

Clutch Pedal Switch

Engine 1

Applied / Released

Released

Crank Voltage Present

Engine 1

Yes/NO

NO

GEN L-Terminal Signal

Engine 1

Voltage / No Voltage

Voltage

Ignition 1 Signal

Engine 1

Volts

Varies

PNP Switch

Engine 1

In Gear / Park / Neutral

Park / Neutral

Starter Relay Command

Engine 1

ON / OFF

OFF

Stop Lamp Pedal Switch

Engine 1

Applied / Released

Released

Powertrain Control Module (PCM) 8.1L (L18)

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

Operating Conditions: Ignition ON/Engine Running

Crank Request Signal

Engine 1

Yes / NO

NO

GEN F-Terminal Signal

Engine 2

%

Varies

GEN L-Terminal Signal Command

Engine 2

ON / OFF

ON

Ignition 1 Signal

Engine 1

0-25.5 V

11.5-14.5 V

PNP Switch

Engine 2

Park / Neutral / In Gear

Park