What does it mean?
C1103 is a Chassis (ABS, traction control, steering) fault code. It indicates: Ignition Voltage Fault .
Symptoms
- Warning lamps appear the moment the key is turned on
- The module drops offline intermittently and returns without warning
- Accessories cut out briefly while driving over bumps
- ABS and stability control unavailable until the ignition is cycled
- The fault repeats whenever the vehicle is started hot or cold, depending on the switch
- Multiple chassis modules store faults at the same time
Likely causes
- Worn ignition switch contacts that drop voltage under load
- Blown, loose or corroded ignition fuse in the fuse box
- High resistance in the ignition feed connector or an inline splice
- Failed or sticking ignition relay
- Weak battery so the ignition line collapses during cranking
- Damaged wiring in the steering column area where the harness flexes
- Faulty voltage monitoring circuit inside the control module
How to fix it
- Check the ignition fuse with a meter and inspect the fuse holder for heat damage
- Back probe the module ignition pin and watch the voltage while cranking and while running
- Perform a voltage drop test from the battery through the ignition switch to the module
- Wiggle test the column harness and the connectors while watching live voltage
- Substitute or bench test the ignition relay
- Repair the corroded terminal, splice or switch contact that causes the drop
- Replace the ignition switch if it drops voltage under load, and only then consider the module