Bendix EC-60 UDS 21 / SPN 629 FMI 2 — ECU (15)

Code Details

Plain-English Meaning

The EC-60 detected an intermittent or erratic internal data condition (ECU (15)). FMI 2 indicates the module's self-diagnostic found internal data that was present but outside expected parameters — rather than absent or completely failed. This category is more closely associated with power supply quality, EMI, or very early hardware degradation than with a definitively failed module. The intermittent nature distinguishes it from a hard FMI 12 hardware failure and gives more justification to investigate external causes first.

The Bendix EC-60 table maps UDS code 21, blink code 13-07, J1587 254-02, and J1939 SPN 629 FMI 2 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 and/or ATC/ESP lamps on — may cycle on and off across power cycles
• Code may be intermittent: present then absent depending on operating conditions
• No specific external sensor or valve circuit associated with the fault
• May correlate with charging system load changes, cold starts, or extreme ambient temperature
• Other voltage-sensitive modules may log intermittent faults simultaneously

Possible Causes

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

• AC ripple from a failing alternator diode entering the EC-60 power supply bus
• Marginal EC-60 supply voltage — drops below specification only under heavy electrical load
• EMI from aftermarket accessories or poorly suppressed accessory electronics
• Intermittent ground fault introducing ground-loop noise into the module power circuit
• Early-stage internal hardware degradation that only manifests under temperature or voltage stress

First Checks

• Measure EC-60 supply voltage under cranking and under peak electrical load — confirm it stays above 11 V at all times.
• Check for AC ripple on the battery bus with a multimeter on AC voltage mode — more than 0.1 V AC with engine running indicates a failed alternator diode.
• Inspect EC-60 power connector and chassis ground connections for corrosion and looseness.
• Clear the code and document whether it recurs under a specific condition (load, RPM, temperature, accessory use) to characterize the intermittent pattern.
• Check for Bendix TSBs for the specific UDS code — some erratic internal codes have known power supply or software resolutions.

Can I Keep Driving?

An ECU internal fault typically disables all ABS, ATC, and ESP functions until the root cause is corrected and the code is cleared. Normal base braking continues. ECU codes do not resolve by themselves — clearing without diagnosis will result in the code returning. Stable power supply quality is the first thing to verify before more extensive diagnosis.

Related Lookup Pages

• FMI 2 explanation
• Bendix manufacturer hub
• ABS / ATC / ESP fault codes
• ABS Light symptom page
• Brake Warning Light symptom page
• Search this code