C1990

Code

Generic C — Chassis

ABS Control Module Internal Fault

Brand: Generic

Type: C — Chassis

Views: UK: 10 EN: 18 RU: 13

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Internal electronic failure in the ABS control module (processor, memory, or power regulation)
Corroded or damaged module connector or pins
Low or intermittent battery voltage or poor power/ground to the module
Moisture/water ingress or physical damage to the module
Faulty or noisy CAN/LIN bus communications
Software corruption or incompatible/failed reflash

Symptoms

ABS warning lamp illuminated (may be steady or flashing)
Traction control or ESC warning lamps illuminated
Loss of ABS/traction control functionality; longer stopping distances in ABS events
Possible loss of CAN communication with ABS module (no data on scanner)
Brake pedal feel may be normal but safety features disabled
Stored internal module diagnostic codes and inability to clear long-term

What to check

Read all ABS and network codes with a professional scan tool; save freeze frame and status data
Inspect ABS module connectors for corrosion, bent pins, or water entry
Verify battery voltage (12.6 V resting, >13.5 V charging) and test for voltage drops during cranking
Check fuse(s) and relay(s) supplying ABS module
Measure power and ground at the module harness (pin-to-pin voltage and ground resistance)
Verify CAN/LIN bus integrity (resistance, termination, observe waveform)

Signal parameters

Module supply voltage: ~12 V nominal; should be stable (no rapid drops)
Ignition-switched supply voltage when ON: ~12–14.5 V
Ground resistance to chassis:
CAN bus idle voltages: CAN_H ≈ 2.5–3.5 V, CAN_L ≈ 1.5–1.8 V (differential ~2.5 V when active)
Wheel speed sensor pulses (if present) — amplitude and frequency should be consistent across wheels
Module wake/sleep control or LIN line levels where applicable per vehicle spec

Diagnostic algorithm

Connect a capable scan tool and record all ABS and network-related codes and live data. Note whether the ABS module responds and whether wheel speed data are present.
Clear codes and attempt to re-create the fault. If fault returns, continue with hardware checks.
Visually inspect the ABS module and connector for corrosion, bent pins, water intrusion, or physical damage. Repair or replace harness/connector as needed.
With ignition ON, measure battery supply and ground at the ABS module connector. Check for intermittent voltage drops while shaking harness (wiggle test).
Check fuses and relays feeding the module; verify wiring continuity to power distribution and chassis ground points.
Verify CAN/LIN communication: measure idle voltages and use an oscilloscope to look for noise, missing termination, or bus errors. Probe other nodes to see if the module is the only non-communicating device.
Inspect wheel speed sensors and related wiring for shorts or open circuits; compare sensor signals on live data to confirm plausibility.
If electrical supply, grounds, wiring, and sensors are good, consult technical service bulletins for firmware updates or known module issues. Attempt reprogramming/reflash only if supported and per vehicle procedures.
If reflash fails or module reports internal error after electrical and network checks, replace the ABS control module with a known-good unit and perform necessary programming/coding. Verify all systems and clear codes.
After repair, road-test vehicle to confirm ABS/ESC operation and monitor for reoccurrence of code.

Likely causes

Failed voltage regulator or protection diode inside ABS module
Seized or shorted internal components due to water intrusion
Broken ground or high-resistance ground at module mounting
Chafed wiring harness causing intermittent short to battery/ground
Aftermarket electrical accessory causing voltage spikes
Module firmware mismatch after previous replacement or update

Fault status

⚠️ Status

ABS Control Module internal fault detected. Safety systems (ABS/ESC) may be disabled. Inspect module power, grounds, communication lines, and module integrity.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 2-4 hours