U1313

Code

DS U — Network/User

Fault in communication with the ABS/ESP ECU on the CAN: No signal / partial triggering message fault

Brand: DS

Type: U — Network/User

Views: UK: 1 EN: 5 RU: 7

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Page language: EN

Causes

ABS/ESP ECU power supply fault (fuse, relay, battery voltage)
Poor or missing ground at ABS/ESP ECU
Damaged, corroded or loose connector at ABS/ESP ECU
Open, shorted or damaged CAN bus wiring (CAN High or CAN Low)
Failed ABS/ESP ECU (internal failure or software fault)
CAN bus termination resistor missing or damaged

Symptoms

ABS and/or ESP/TRC warning lamp illuminated
Reduced or disabled ABS/ESP functionality; braking feel may change under ABS events
Other modules report communication loss with ABS (scan tool shows U-codes)
Intermittent or permanent loss of vehicle stability control functions
Possible additional warning lights or limp-home behavior if related modules fail to communicate

What to check

Verify battery voltage (key on and cranking) and inspect main fuses/relays for ABS power circuit
Visually inspect ABS/ESP ECU connector for corrosion, bent pins, water ingress and secure locking
Check chassis/engine ground connections near ABS ECU for cleanliness and tightness
Use a scan tool: confirm DTCs in ABS module and other modules, check module presence on network
Measure CAN High and CAN Low voltages at ABS connector with ignition ON
Check CAN bus termination resistance (approx. 60 ohms across CAN H and CAN L with power off)

Signal parameters

Typical CAN recessive voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (approx. mid-rail)
Typical CAN dominant voltages: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2.0 V)
Common ABS/ESP CAN baud rate: often 500 kbps (manufacturer-dependent) — verify exact rate
ABS/ESP messages are usually periodic (tens of ms); absence or irregular timing indicates fault
Termination resistance: approx. 60 Ω across CAN_H and CAN_L (with vehicle power off)

Diagnostic algorithm

Record freeze-frame data and all stored DTCs. Note whether code is steady or intermittent and any related U-codes.
Check battery voltage and inspect/replace any blown fuses and ABS power/ignition relays as required.
Visually inspect ABS ECU connector; disconnect and inspect pins for corrosion, damage or bent pins, then reconnect securely.
Verify good chassis/engine ground(s) and ECU power feeds with a DVOM (key on).
With key ON, measure CAN_H and CAN_L at the ABS connector. Compare to typical levels (recessive/dominant).
Measure termination resistance across CAN_H and CAN_L with power off; expect ~60 Ω. If open or incorrect, trace to missing termination or wiring fault.
Use a scan tool to check if ABS module is present and responding. If module absent, attempt communication at other network nodes to localize break.
If voltages are present but messages missing or corrupted, capture bus traffic with an oscilloscope/CAN analyzer to look for bus-off states, contention, noise, or malformed frames.
Isolate wiring segments: disconnect neighboring modules or splice connectors to determine if a specific harness section causes the fault.
If wiring, connectors and power/grounds check good and ABS module still not communicating, consider ABS ECU software update or replacement per manufacturer procedure. After repairs, clear codes and perform function test and road test.
Document findings and replace or repair components only after confirming root cause; do not replace ECU without proper isolation testing.

Likely causes

Faulty or loose connector/power/ground at the ABS/ESP ECU
Open or short in CAN wiring between ABS/ESP ECU and main CAN trunk
Bus-off condition or another module pulling the bus dominant
Failed ABS/ESP ECU

Fault status

⚠️ Status

No signal or partial/irregular CAN messages received from the ABS/ESP ECU — communication fault on CAN network.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5 - 4.0 hours

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