What does it mean?
C1107 is a Chassis (ABS, traction control, steering) fault code. It indicates: ECS ECM Generator "L" Terminal Voltage Is High .
Symptoms
- Charge or battery warning lamp behaves oddly, stays lit, or never comes on at key up
- Warning lamps for the affected system on the dash
- Charging voltage measured at the battery is too high or unstable
- Lights brighten and dim with engine speed
- Battery gets hot or loses electrolyte over time
- The system that relies on the signal switches to a reduced function state
Likely causes
- Faulty alternator voltage regulator holding the lamp terminal high
- Open charge warning lamp bulb or a failed lamp driver in the instrument cluster
- Break or high resistance in the "L" terminal wire between alternator and cluster
- Short to a battery feed where the thin lamp wire runs beside heavy charging cables
- Corroded connector at the alternator, often heat damaged after long service
- Poor engine to body ground raising the reference the module measures against
- Internal fault in the module that monitors the terminal
How to fix it
- Measure battery voltage at idle and at raised speed, with and without electrical load
- Confirm the charge warning lamp illuminates with the key on and goes out once running
- Back probe the "L" terminal and compare voltage with the engine stopped and running
- Inspect the alternator connector and wiring for heat damage, corrosion and chafing
- Clean and tighten the engine to body ground straps
- Replace the regulator or alternator if the output or terminal voltage stays out of specification
- Repair the lamp circuit or cluster driver if the terminal voltage is high with the alternator disconnected