GM Service Manual Online
For 1990-2009 cars only

Engine Control Module (ECM)

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

Ignition ON/Engine OFF

Crank Request Signal

Electrical/Theft Data

Yes/No

No

Generator L Terminal Signal Command

Electrical/Theft Data

Off/On

Off

Generator F Terminal Signal

Electrical/Theft Data

%

10 - 90%

Ignition 1 Signal

Electrical/Theft Data

volts

9.6 - 14.4v

PNP Switch

Electrical/Theft Data

Park/Neutral, In Gear

Park/Neutral

Starter Relay Command

Electrical/Theft Data

Off/On

Off

Starter Relay Circuit Status

Electrical/Theft Data

Incomplete, Short Gnd/Open, Short to B+, OK

OK

TR Sw.

Transmission Data

Park, Reverse, Neutral, Drive 5, Drive 4, Drive 3, Drive 2, Drive 1

Park

Powertrain Control Module (PCM)

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

Ignition ON/Engine OFF

Generator L Terminal Signal Command

Engine Data 2

Off/On

Off

Generator F Terminal Signal

Engine Data 2

%

10 - 90%

Ignition 1 Signal

Engine Data 1, Engine Data 2, Engine Data 3

volts

9.6 - 14.4v

Starter Relay Command

Engine Data 3

Off/On

Off

TR Sw.

Transmission Data

Park, Reverse, Neutral, Drive 5, Drive 4, Drive 3, Drive 2, Drive 1

Park