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P1779: Transmission Control Indicator Lamp Circuit Malfunction

FORD LINCOLN MERCURY BUICK CADILLAC CHEVY GM GMC
Severity
Medium
System
Manufacturer-Specific Powertrain

What Does P1779 Mean?

P1779 is a manufacturer-specific diagnostic trouble code: Transmission Control Indicator Lamp Circuit Malfunction. This code applies to FORD, LINCOLN, MERCURY, BUICK, CADILLAC vehicles. Unlike generic OBD-II codes, manufacturer-specific codes are defined by the vehicle maker and may only apply to certain makes and models.

Symptoms of P1779

Common Causes

Frequently Asked Questions

What does P1779 mean?
P1779 indicates: Transmission Control Indicator Lamp Circuit Malfunction. The vehicle's computer has detected that the Transmission Control Indicator Lamp is not operating within its expected parameters and stored this diagnostic trouble code.
Can I drive with code P1779?
You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with P1779 for extended periods may cause additional problems.
How much does it cost to fix P1779?
Repair costs for P1779 typically range from $80 to $300, depending on the root cause. Simple wiring or connector repairs are on the lower end, while component replacement costs more. A proper diagnosis ($80–$150 at most shops) will identify the exact cause before committing to expensive parts.

What To Do Next

Possible Fixes

  • 🔧 Inspect and repair Transmission Control Indicator Lamp wiring and connectors
  • 🔧 Replace faulty Transmission Control Indicator Lamp
  1. 1
    Find your vehicle above

    Click your make and model for real owner reports and common causes specific to your vehicle.

  2. 2
    Check for recalls

    Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.

  3. 3
    Get a professional diagnosis

    A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.

Related Codes

P1700 Transmission Indeterminate Failure (Failed to Neutral) P1701 Transmission Range Sensor Reverse Engagement Error P1702 Transmission Range Sensor Circuit Intermittent P1703 Low Clutch Timing Control Solenoid Valve Circuit Malfunction P1704 Digital TRS Failed to Transition States in KOEO / KOER P1705 2-4 Brake Pressure Solenoid Valve Solenoid D Circuit P1706 TCM A/T Gear Position Switch Circuit Open P1707 Transfer Case Neutral Indicator Hard Fault Present P1708 Clutch Switch Circuit Malfunction P1709 Park or Neutral Position Switch Out of Self-Test Range