Code
P1666
HUMMER
P — Powertrain
Driver 3 Line 6
AI status
Completed
Completed
100%
Causes
- Short to battery on driver output
- Short to ground on driver output
- Open circuit (broken wire, poor pin contact)
- High current draw from a failed actuator or shorted connector
- Corroded or damaged connector/pins at the load or module
- Blown fuse or tripped relay in the circuit
Symptoms
- Related component(s) controlled by Driver 3 Line 6 do not operate or operate intermittently
- Associated fuse may be blown or relays may not engage
- Malfunction Indicator Lamp (MIL) illuminated and fault stored
- Loss of function for the specific system the driver controls (depends on vehicle configuration)
- Possible high current draw or battery drain if shorted
What to check
- Read and record freeze frame and freeze frame data with a capable scan tool
- Identify which circuit/component is controlled by Driver 3 Line 6 using the vehicle wiring diagrams
- Visually inspect harness, connector, and pins for corrosion, damage, melting or water intrusion
- Check relevant fuses and relays for open or evidence of overheating
- Back-probe the driver connector and check voltage with key ON and during commanded operation
- Perform wiggle test on harness while observing live data or watching for code set
Signal parameters
- Supply voltage at module: ~battery voltage (12–14.5 V with engine running)
- Driver output behavior: either low-side switch (0 V when active) or high-side (battery voltage when active) depending on design — consult wiring diagram
- Expected idle/standby: open/high impedance (no excessive current)
- When commanded ON: voltage toggles to expected active level (0 V or ~VBatt) or shows PWM duty cycle if modulated
- Typical current draw: depends on actuator — small solenoids/relays usually specified value) suggests short or failed load
- No high frequency noise or irregular PWM outside specified frequency range for that circuit
Diagnostic algorithm
- Confirm code is current and capture freeze frame data with scan tool
- Consult vehicle-specific wiring diagram to identify the exact component and pin assignments for Driver 3 Line 6
- Perform a visual inspection of connectors, wiring, and related components for damage, corrosion, or signs of overheating
- With ignition ON (engine off) back-probe the driver output and observe voltage while commanding the circuit ON/OFF from the scan tool; note if output reaches expected active level
- Disconnect the actuator/load from the driver circuit; clear codes and attempt to operate the circuit. If code does not return, suspect the actuator or harness to the actuator
- If the code returns with the load disconnected, suspect wiring short, poor ground, or module internal fault. Perform resistance checks between the driver output and battery/ground to locate shorts or opens
- Measure current draw of the actuator directly (bench test or in-circuit with a fused jumper) and compare to specification. Replace actuator if it draws excessive current.
- Repair any wiring harness damage, corroded connectors, or blown fuses. After repairs, clear codes, retest operation and perform road test or functional test to verify repair
- If wiring and actuator test good and fault persists, follow manufacturer guidance for module testing and replacement; some modules require programming or reflash after replacement
Likely causes
- Damaged or corroded connector at the controlled actuator
- Short to ground in harness near actuator or module
- Failed actuator drawing excessive current
- Open or intermittent wiring between module and load
- Internal driver transistor or module failure (less common than external wiring/actuator faults)
Fault status
Status
Driver 3 Line 6 fault recorded: control module detected open/short/excessive current or internal driver failure on the specified output circuit. Diagnostic action required to isolate wiring, load, or module fault.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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Repair manuals
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138
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