Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Scan Tool Data Definitions
- Battery Voltage
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The scan tool displays 0-20 volts. The scan tool displays the voltage as received on the battery positive voltage circuit of the body control module (BCM) or instrument panel cluster (IPC) module.
- Crank Request Signal
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The scan tool displays Yes/No. The scan tool displays the status of the crank request signal.
- Current Gear
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The scan tool displays P/N/1st/2nd/3rd/4th/5th/Reverse. The scan tool displays the current gear that the transmission is in.
- GEN F-Terminal Signal
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The scan tool displays the percentage of the field current.
- GEN L-Terminal Signal Command
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The scan tool displays On/Off. The scan tool displays Off until the engine is running, at which time it will display On.
- GEN L-Terminal Signal Command
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The scan tool displays 0-100 percent. The scan tool displays the percentage of the output voltage of the generator.
- Ignition 1 Signal
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The scan tool displays 0-20 volts. The scan tool displays the voltage as received on the ignition 1 circuit to the powertrain control module (PCM).
- Ignition 1 Signal
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The scan tool displays On/Off. The scan tool displays the status of the signal received on the ignition 1 circuit to the engine control module (ECM).
- IMS
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The scan tool displays 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, Drive2\Drive 1, Invalid, Open. The scan tool displays the physical position of the internal mode switch (IMS) of the transmission.
- PNP Switch
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The scan tool displays Park/Neutral or In Gear. The scan tool displays the position of the transmission setting.
- Regulated Voltage Control Current Sensor
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The scan tool displays 1-100 percent. The scan tool displays the percentage of the battery current sensor pulse width modulation (PWM) duty cycle signal.
- Starter Relay Circuit History
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The scan tool displays OK/Open/Short/Invalid. The scan tool displays history status of the crank relay.
- Starter Relay Command
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The scan tool displays ON/OFF. The scan tool displays Off until the ignition is placed into the CRANK position, then it reads On.
- Starter Switch
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The scan tool displays Released/Cranking. The scan tool displays Cranking when the ignitions switch is in the Start position.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.