GM Service Manual Online
For 1990-2009 cars only

Body Control Module (BCM)

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

Operating Conditions: Ignition ON/Engine OFF

Battery Voltage Signal

BCM, Power Mode

Volts

12.6 Volts

Power Mode

BCM, Power Mode

Off, Accessory, Run, Crank Request

Off

Idle Boost Level

BCM, Power Mode

Numeric

0

Run Relay Command

BCM, Power Mode

On, Off

On

Run/Crank Relay Command

BCM, Power Mode

On, Off

On

Engine Control Module (ECM)

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

Operating Conditions: Ignition ON/Engine OFF

Crank Request Signal

ECM, Electrical/Theft Data

Yes/No

No

GEN F-Terminal Signal

ECM, Electrical/Theft Data

%

0 %

GEN L-Terminal Command

ECM, Electrical/Theft Data

%

0 %

GEN L-Terminal Circuit Status

ECM, Electrical/Theft Data

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

OK

Ignition 1 Signal

ECM, Electrical/Theft Data

Volts

12.6 V

PNP Switch

ECM, Electrical/Theft Data

In Gear, Park/Neutral

Park/Neutral

Starter Relay Command

ECM, Electrical/Theft Data

On/Off

Off

Starter Relay Circuit Status

ECM, Electrical/Theft Data

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

OK

L61, LZ4 Transmission Control Module (TCM)

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

Operating Conditions: Ignition ON/Engine OFF

TR Sw.

TCM, Data Display, Transmission Data

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

Park

LZ9 Transmission Control Module (TCM)

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

Operating Conditions: Ignition ON/Engine OFF

IMS

TCM, Data Display, Transmission Data

Drive 3, Drive 4\Drive 3, Park\Reverse, Reverse, Drive 3\Drive 2, Drive 2, Park, Invalid, Neutral\Drive 4, Drive 4, Neutral, Reverse\Neutral, Drive 1, Drive 2\Drive 1, Invalid

Park