Case Study: ABS Warning Light Diagnosis on a Renault Trafic

Fault Fixer Case Study – Internal ABS Control Module Failure

Service: Mobile Vehicle Diagnostics
Vehicle: Renault Trafic LL30 Extra Blue dCi
Mileage: 10,339 km
Fault Area: ABS / CAN Communication Network

Overview: Renault Trafic ABS Warning & CAN Communication Faults

Fault Fixer was contacted to investigate an ABS warning light on a nearly new Renault Trafic. Previous fault code scans had identified CAN communication errors, but no clear diagnosis or repair direction had been provided.

The customer required a definitive, warranty-safe diagnostic report to identify whether the issue was wiring-related, software-related, or an internal module failure.

Customer Reported Issue

  • ABS warning light illuminated
  • Multiple CAN communication fault codes present
  • Faults returned immediately after clearing
  • No drivability symptoms, but safety system compromised

Initial Vehicle Condition Assessment

Before diagnostic testing, a full condition check confirmed:

  • No accident damage
  • No corrosion or water ingress
  • No aftermarket electrical modifications
  • Original factory wiring and components intact

This immediately ruled out several common causes of ABS communication faults.

Fault Codes Identified (ABS Control Module)

The following fault codes were stored and active:

  • U227687 – Lost communication on CAN_CHASSIS2 (Active)
    U215687 – Lost communication on CAN_V1 (Active)

Both codes returned instantly after clearing, without an ignition cycle—an important diagnostic indicator.

Diagnostic Tests Performed

1. Ground (Earth) System Verification

Tests carried out:

  • Battery negative to body ground resistance: 0 ohms
  • Battery negative to engine ground resistance: within manufacturer specification
  • Additional direct ground bridge applied to engine block

Result:  No change in fault behaviour.

Conclusion:  Ground integrity confirmed. Ground-related electrical faults ruled out.

2. ABS Module Communication & Live Data Analysis

Findings:

  • ABS control module accessible via diagnostic equipment
  • Fault codes readable and clearable
  • Live data menu available
  • All live data parameters inactive
  • No wheel speed, brake pressure, or status data displayed

Interpretation:  The diagnostic communication layer is functional, but internal real-time processing inside the ABS module is not operating.

3. CAN Network Behaviour Assessment

Observations:

  • CAN communication faults generated by the ABS module itself
  • Other control units reporting loss of communication with ABS
  • No evidence of CAN wiring damage
  • No network-wide CAN failure detected

Conclusion:  External wiring and vehicle CAN network integrity confirmed.

Technical Conclusion: ABS Control Module Internal Failure

The ABS control module is partially responsive at a diagnostic level but internally non-functional.

With grounding, power supply, wiring and CAN network integrity fully tested and excluded, the fault pattern is consistent with an internal ABS ECU failure, not an external electrical or software issue.

This diagnostic profile is typical of internal control module failure on modern vehicles.

Repair Recommendation

  • Warranty repair required
  • Replacement of the ABS control module necessary
  • Fault cannot be resolved through:
    • Wiring repair
    • Grounding repair
    • Software updates or coding

The vehicle qualifies for manufacturer warranty repair due to age and mileage.

Outcome for the Customer

  • Clear, evidence-backed diagnosis
  • Professional diagnostic report suitable for dealer and warranty submission
  • No unnecessary parts replacement
  • No trial-and-error repairs
  • Faster resolution and reduced downtime

Why Professional Diagnostics Matter

Modern vehicles rely on complex communication networks.
Simply reading fault codes is not enough.

At Fault Fixer, we:

  • Verify power and ground integrity
  • Analyse live data behaviour
  • Confirm CAN network health
  • Prove root cause before recommending repair

This approach protects customers from unnecessary costs and misdiagnosis.

Fault Fixer Mobile Vehicle Diagnostics

We specialise in:

  • ABS fault diagnostics
  • CAN communication faults
  • Warning light investigations
  • Warranty-safe diagnostic reports
  • Mobile vehicle diagnostics across the UK

If your vehicle has warning lights or unresolved fault codes, Fault Fixer provides answers, not guesses.

Call Us Now
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