Bendix EC-60 UDS 135 / SPN 790 FMI 1 — SA Right WSS Excessive Air Gap

Code Details

Plain-English Meaning

The EC-60 is receiving a signal from the steer axle right wheel speed sensor but the amplitude is below normal — the sensor is mounted too far from the tone ring. The circuit is intact; the issue is physical proximity.

The Bendix EC-60 table maps UDS code 135, blink code 03-01, J1587 002-01, and J1939 SPN 790 FMI 1 to this ABS/ATC/ESP diagnostic entry. The Bendix source indicates an ABS and/or ATC/ESP warning lamp can be on for this entry. The EC-60 continuously monitors wheel speed sensor circuits, pressure modulation valve output drivers, supply voltage quality, J1939 network data from the engine and transmission controllers, and internal self-diagnostic routines. When any monitored value falls outside its acceptable range — or a circuit does not respond as the module expects — the EC-60 logs a diagnostic trouble code and may disable the affected ABS, ATC, or ESP function. Bendix ACOM Pro or a compatible diagnostic interface is the required tool for reading live sensor data, running actuator tests, performing calibrations, clearing latched codes, and adjusting EC-60 configuration parameters. Generic J1939 scan tools can read the SPN/FMI but cannot access EC-60-specific live data screens or configuration settings.

Common Symptoms

• ABS lamp on
• Signal present at higher speeds but weak or absent at very low speed
• Sensor resistance test normal
• May be intermittent in cold weather as components contract
• Often appears after axle service, bearing replacement, or hub work

Possible Causes

Possible causes may include the items below. The list is not a parts diagnosis.

• Sensor mounting bracket bent, cracked, or shimmed incorrectly after axle service
• Tone ring replaced with a different tooth profile or slightly smaller diameter
• Hub wear or bearing spacer error that moved the tone ring farther from the sensor plane
• Sensor tip physically recessed from impact
• Corrosion or debris on sensor face adding effective distance

First Checks

• Measure the air gap at the sensor tip — Bendix spec is typically 0.25–1.5 mm (confirm in service manual for this application).
• Confirm the sensor is fully seated and the mounting screw is tight.
• Inspect for a replacement tone ring with a different profile from the original.
• Check for bearing play that could allow intermittent gap variation during braking.
• On the steer axle, trace the harness through the steering knuckle flex area — wire fatigue at the knuckle is a common cause of intermittent and hard open faults from repeated steering-cycle flexing.
• Compare gap across several tooth positions to rule out runout as the primary cause.

Can I Keep Driving?

ABS is disabled at the affected wheel channel while this fault is active. Normal hydraulic or air base braking continues unaffected — the vehicle can brake, but anti-lock protection is not available at that corner. Drive conservatively to a service location. Do not operate in conditions where ABS intervention would be likely, such as slippery surfaces or loaded highway braking. Clear only after root-cause repair.

Related Lookup Pages

• FMI 1 explanation
• Bendix manufacturer hub
• ABS / ATC / ESP fault codes
• ABS Light symptom page
• Brake Warning Light symptom page
• Search this code