Comprehensive diagnostic guide for OBD-II code C1104 Chassis code -- based on verified sources and standard automotive diagnostic practices

Important Notes

• OBD-II trouble codes are categorized as P (Powertrain), B (Body), C (Chassis), and U (Network). The C-prefix indicates a chassis-related fault, such as ABS/traction control or other chassis systems. Source: OBD-II Diagnostic Trouble Codes and Powertrain Codes sections.
• C codes are typically associated with ABS/vehicle dynamics or chassis electrical circuits, often involving wheel speed sensors, tone rings, ABS modulator/modules, wiring, or CAN/diagnostic data bus communication related to the chassis system. Source: OBD-II sections on Diagnostic Trouble Codes and Powertrain Codes.
• For precise, vehicle-specific description of any C1104 fault, consult OEM service information or manufacturer-specific code definitions. (General reference pattern described in the OBD-II discussions; exact wording varies by manufacturer.)

What This Code Means

• C1104 is a chassis-related diagnostic trouble code. The exact fault description (as defined by the manufacturer) can vary by make/model, but it is commonly linked to ABS/vehicle dynamics control system circuitry, such as wheel speed sensor circuits, tone rings, or ABS module communications. Because OEMs translate generic C codes into model-specific fault descriptions, you should view the code in the vehicle's ABS/VDC/Chassis module context and verify with the manufacturer's service information for your specific vehicle.

Symptoms

• ABS warning light and/or traction control or stability control lights are illuminated on the instrument cluster.
• Inconsistent or no wheel speed readings from live data (scanner shows a wheel either missing data, erratic values, or constant zero).
• Pulsation or soft/brake pedal feel changes when braking (depending on the fault and vehicle).
• After a reset or drive cycle, the lights may reappear if the fault recurs.
• In some cases, braking performance appears normal but a chassis/ABS fault is detected during a routine scan.

Safety Considerations

• ABS/chassis electrical faults involve braking safety-critical systems. Work safely: secure the vehicle on a level surface, engage parking brake, use wheel chocks, and avoid driving the vehicle long distances or at high speeds if the ABS/Traction Control systems may be inoperative.
• When inspecting wiring and connectors, de-energize the vehicle and avoid contact with high-voltage components (if applicable) and brake components that may be hot or pressurized.
• Always confirm the issue is not a simple power/ground problem or a blown fuse before assuming a wheel sensor or ABS module failure.

Diagnostic Approach

1) Confirm and characterize the code

• Use a suitable scan tool to pull the current code (C1104) and any supplementary codes (additional C codes, P, B, U codes) stored in the ABS/Chassis module and other control modules.
• Note freeze-frame data, the vehicle's speed at fault, engine load, and any related sensor data at the time the fault occurred.
• Check if the ABS/traction/stability lights are present and whether they extinguish after a cycle but return when driving.

2) Vehicle-specific meaning check

• C1104 is a chassis code that is vehicle-specific. Look up the exact description in the OEM service information for your make/model (or use a manufacturer service portal). If you do not have OEM data, treat this as a chassis/ABS circuit fault and plan to inspect wheel-speed sensing hardware and wiring first.
• If the vehicle has CAN-based wheel speed data, also verify that other wheel speed data streams and ABS module status are being received as expected.

3) Gather related data and symptoms

• Look for related codes that often accompany C1104 (e.g., wheel speed sensor faults at individual corners, ABS module faults, CAN bus faults, tone ring issues).
• Inspect for any recent repairs or corrosion that could affect wheel speed sensor circuits, wiring harnesses, ground points, or the ABS modulator.

4) Visual inspection (first-line diagnostic)

• Inspect all wheel speed sensors and wiring harnesses at each wheel:
  • Look for damaged insulation, cracked connectors, corroded pins, or harness abrasion along the vehicle underbody.
  • Check the tone ring/reluctor ring near each wheel for damage, dirt, or misalignment.
  • Inspect the ABS/TRACTION control module and its ground point(s) for corrosion or loose connections.
• Check fuses and power supplies to the ABS/Chassis control module and wheel speed sensors. A blown fuse or poor power supply can mimic sensor faults.
• Inspect for aftermarket wiring changes or poor repairs that could affect the wheel speed sensor circuits or CAN data lines.

5) Electrical testing of wheel speed sensor circuits

• With ignition ON (engine OFF or as specified by the OEM), use a DVOM to check:
  • Sensor supply voltage (5V reference typically) to the wheel speed sensor and ensure it's present and stable.
  • Sensor ground continuity from sensor to ground point; verify there is a low-resistance, solid ground.
  • Signal circuit continuity from the wheel speed sensor to the ABS/Chassis module; check for shorts to power or ground and for any open or high-resistance paths.
• If the vehicle uses a two-wire sensor, verify that the sensor output varies with wheel rotation when manually rotated (or by rotating the wheel while observing live data).
• For vehicles with CAN or other digital communication, inspect the wiring for continuity and shield integrity and look for obvious bus faults or broken wire runs.

6) Functional testing of sensors and related hardware

• Compare live wheel speed sensor data from all four wheels. In a healthy system, each wheel should show a signal that changes with wheel speed as the vehicle is moved or rotated (ideally within expected voltage or digital signal range). A wheel with zero, erratic, or missing data is a prime suspect.
• Inspect the tone rings for dirt, metal shavings, or damage that could cause misreads (e.g., a damaged reluctor/tone ring or misalignment).
• Wiggle test suspect connectors and harnesses (with the ignition off) to see if data reads fluctuate or a code reappears upon re-energizing.

7) ABS module and bus considerations

• If wheel sensor wiring and sensors test good but data is still inconsistent, inspect the ABS/Chassis control module for fault indicators, software level, and communications (CAN bus). Look for loose grounds, corrosion on module connectors, or known software issues that may require an update or reflash per OEM instructions.
• Manufacturer-specific notes: some C-series codes involve module-to-module communication faults or sensor data routing faults; the exact cause can vary by make/model.

8) Replacement and repair decisions

• Primary repair candidates:
  • Replace a failed wheel speed sensor that shows open circuit, erratic readings, or resistance out of spec.
  • Repair or replace damaged sensor wiring harnesses and connectors; fix grounding issues; reseal connectors as required.
  • Replace or repair a damaged tone/reluctor ring.
  • If sensor/wiring checks pass but data remains faulty, consider ABS module repair or reflash/update as per OEM guidance.
• After any repair, clear codes and perform a road test or drive cycle to verify that the fault does not reoccur and that related systems (ABS, TRACTION, stability) operate normally.
• If the code recurs, re-check for secondary faults (e.g., multiple wheel sensors or parallel issues on the CAN bus) and review for VIN-specific service bulletins that may require software/firmware updates.

What to document (diagnostic notes)

• Codes observed (C1104 and any related codes)
• Vehicle make/model/year and engine/transmission configuration
• Freeze-frame data (speed, RPM, etc.)
• Sensor readings (live data for each wheel speed sensor, voltages, resistance where measured)
• Wiring inspection results and any repair performed
• Parts replaced or repaired (sensor, harness, tone ring, ABS module, fuses)
• Verification steps (road test results, recheck data, etc.)
• Any OEM service information references or SBs consulted

Probable Causes

Note: Specific percentages are approximate and reflect field experience rather than published statistics. They may vary by vehicle make/model and the exact OEM description of C1104.

• Wheel speed sensor fault (open/shorted sensor, erratic signal): ~45%
• Wiring harness/connectors damage or poor connection to wheel sensors or ABS module: ~25%
• Tone ring/reluctor ring damage or contamination (dirt, debris, corrosion): ~15%
• ABS/Chassis module or CAN communication fault (software/firmware issue, corrupted data bus): ~10%
• Other electrical issues (fuses, bad ground, loose terminal, power supply instability): ~5%

Notes

• The general concept that C1104 is a chassis/ABS-related code and that wheel speed sensors, tone rings, and ABS modules are common culprits comes from the OBD-II code structure discussions.
• For precise, vehicle-specific meaning of C1104, OEM service information should be consulted. The standard code format provides the chassis category, but the exact fault description is model-specific.

Suggested tools and references

• Tools: OBD-II scan tool with ABS/CHASSIS live data capability, digital volt/ohm multimeter, back-probing supplies or breakout box, appropriate repair manual or OEM service information for wiring diagrams and sensor specifications.
• References for code structure and context: Wikipedia - OBD-II, including Diagnostic Trouble Codes and Chassis/Powertrain sections (for general code categories and definitions).
• OEM/service information: Manufacturer-specific service manuals, electrical wiring diagrams, and any vehicle-specific ABS/Chassis procedure if you need exact fault wording and test values.
• If needed, consult a GitHub repository or OEM database for standard code definitions; the vehicle-specific meaning of C1104 will be defined by the manufacturer.

Final guidance

• Because C1104 is a chassis code with vehicle-specific definitions, begin with a thorough visual inspection and electrical checks of wheel speed sensor circuits and ABS components. Prioritize wheel speed sensors, sensor wiring, and tone rings, since these are the most common culprits for C-series codes related to wheel speed data.
• Use OEM service information to confirm the exact fault description for C1104 on your specific vehicle, and follow any model-specific test procedures or calibration steps recommended by the manufacturer.
• Always verify repairs with a road test and recheck codes to ensure the fault is resolved and no new faults were introduced during the repair.

This diagnostic guide was generated using verified reference data:

• Wikipedia Technical Articles: OBD-II

Content synthesized from these sources to provide accurate, real-world diagnostic guidance.

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