Bendix EC-60 UDS 205 / SPN 1056 FMI 5 — Trailer PMV REL Solenoid Open Circuit

Code Details

Plain-English Meaning

The EC-60 detected a fault in the trailer PMV circuit. Trailer PMV faults disable trailer ABS while tractor ABS continues to operate. The fault is often trailer-side or in the 7-way connector rather than in the tractor EC-60.

The Bendix EC-60 table maps UDS code 205, blink code 20-03, J1587 066-05, and J1939 SPN 1056 FMI 5 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; possibly a trailer-specific indicator
• Trailer ABS disabled while tractor ABS continues
• Scan tool shows Bendix EC-60 UDS 205 / SPN 1056 FMI 5 when trailer is connected
• Code may clear when the trailer is disconnected
• Normal tractor braking unaffected

Possible Causes

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

• Damaged or corroded 7-way trailer connector reducing power to trailer PMV
• Trailer PMV solenoid open, shorted, or trailer harness fault
• Trailer ABS module fault on the trailer itself
• Broken or corroded pin in the tractor-side 7-way socket
• High resistance in trailer harness due to damage or multiple corrosion points

First Checks

• Disconnect the trailer and recheck — if the fault clears, the problem is trailer-side.
• Inspect the 7-way electrical connector on both tractor and trailer for corrosion and bent pins.
• Check voltage at the trailer ABS power pin (pin 7 on SAE J560) with trailer connected.
• If fault is trailer-side, diagnose the trailer ABS module and PMV circuit on the trailer separately.
• Verify the tractor EC-60 is not also reporting tractor-side faults that could be confused with trailer issues.

Can I Keep Driving?

A pressure modulation valve fault means the EC-60 may not be able to independently modulate brake pressure at the affected wheel during ABS activation. Normal brake application still functions, but anti-lock control at that corner is compromised. If the PMV cannot release pressure during a lockup event, wheel lockup may occur despite the ABS system being otherwise functional. Address before operating in conditions requiring aggressive braking.

Related Lookup Pages

• FMI 5 explanation
• Bendix manufacturer hub
• ABS / ATC / ESP fault codes
• ABS Light symptom page
• Brake Warning Light symptom page
• Search this code