What does it mean?
C1735 is a Chassis (ABS, traction control, steering) fault code. It indicates: Ignition Signal .
Symptoms
- Chassis system warning lamps on, often appearing only after the engine has been cranked
- The system is unavailable at start-up but works normally after a restart
- Momentary module resets: gauges dip, telltales flash, displays reboot
- Occasional no-crank or accessory dropouts at the same time
- A very low voltage recorded in the freeze frame data for this code
Likely causes
- Worn ignition switch contacts letting the ignition feed drop momentarily
- Blown or intermittently open fuse on the ignition supply for this module
- Corroded, loose or partially seated connector in the ignition feed circuit
- Chafed ignition supply wire making intermittent contact with the body
- Faulty ignition relay or a relay socket with burnt terminals
- Poor module ground, which makes the ignition input look absent to the module
- Weak battery causing a deep voltage drop during cranking
- Failed input circuit inside the module itself
How to fix it
- Check battery state of charge and measure cranking voltage before diagnosing the circuit
- Inspect the ignition supply fuses and swap-test the ignition relay with a known good one
- Voltage drop test between battery positive and the module ignition pin with the key on
- Watch the module's ignition voltage in live data while wiggling the harness and the ignition switch connector
- Measure the module ground resistance and clean the ground point if needed
- Repair the switch, relay socket or harness fault that is found and retest
- Replace the module only after a stable ignition voltage at its connector has been proven