Wiring fault on the circuit driven by Line 6, such as a short to earth, short to voltage or open circuit; Faulty actuator, solenoid or relay on that circuit drawing too much current or having an open coil; Corroded, loose or pushed-out pins at the control unit connector or the component connector; Poor power or earth supply to the control unit or to the driven component; Internal fault in the control unit's driver stage; Water ingress or heat damage to the control unit or its harness.

P1646

Driver 1 Line 6.

Chevrolet
Powertrain
Manufacturer code
Medium severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
6: AreaComputer and output circuits
46: FaultThe specific fault in that area

What it means

On Chevrolet vehicles P1646 is reported as 'Driver 1 Line 6'. This points to a fault in one of the control unit's internal output driver circuits, or in the circuit it switches. The control unit saw the driver's output state not match what it commanded, such as an open circuit, a short or an over-current condition. Which component sits on Line 6 depends on the model, engine and year, so the wiring diagram for the exact vehicle is needed.

Symptoms

Check engine light on
Another output not working, such as a relay, solenoid or actuator, depending on what Line 6 controls
Poor running, hesitation or a rough idle on some vehicles
Other driver or circuit codes stored alongside it
Fault that comes and goes, often with heat, vibration or damp

Possible causes

Wiring fault on the circuit driven by Line 6, such as a short to earth, short to voltage or open circuitlikely
Faulty actuator, solenoid or relay on that circuit drawing too much current or having an open coillikely
Corroded, loose or pushed-out pins at the control unit connector or the component connectorpossible
Poor power or earth supply to the control unit or to the driven componentpossible
Internal fault in the control unit's driver stagepossible
Water ingress or heat damage to the control unit or its harnessrare

How to diagnose

Read all stored and pending codes and note any related driver or circuit codes
Read the freeze frame data to see engine speed, load, temperature and battery voltage when the code set
Find the Line 6 output in the wiring information for this exact model and engine, and identify the component it drives
Visually inspect the harness, connectors and earths on that circuit for chafing, corrosion, heat damage or water
Check battery condition and charging voltage, and the control unit's power and earth supplies
Measure the resistance of the driven component and compare it with the specification
Test the circuit for continuity and for shorts to earth or voltage, with the connectors disconnected
Clear the code and road test, monitoring the output with a scan tool, to see whether the fault returns before condemning the control unit

How to fix

Repair or replace any damaged wiring or terminals found on the circuit
Replace the faulty actuator, solenoid or relay if its resistance or operation is out of specification
Clean and secure the connectors and earth points, and fix any water ingress
Correct any low-voltage or poor-earth problem on the control unit supplies
Replace or repair the control unit, with any programming it needs, only after the wiring and components are proven good

Can I keep driving?

Medium severity

The car can usually be driven carefully for a short time, but get it checked soon because the affected output may not work properly. If it runs badly, loses power or other warnings appear, stop driving and have it inspected.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.