U1124

Code

DS U — Network/User

Fault: absence of communication with the pneumatic suspension ECU: No signal

Brand: DS

Type: U — Network/User

Views: UK: 0 EN: 4 RU: 5

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Pneumatic suspension ECU has no power (fuse, relay, battery supply)
Bad or missing ground at the ECU
Damaged, corroded or disconnected ECU connector/wiring
Open, short or high resistance on the CAN/data bus wiring (CAN High/Low)
Faulty pneumatic suspension ECU
Gateway or another module not forwarding messages (network/gateway fault)

Symptoms

Suspension warning lamp/message on dash
Loss of adjustable ride height or air suspension functions
Vehicle sits at incorrect height or becomes soft/harsh
Related modules may log communications errors or fail to operate
No response when querying pneumatic suspension ECU with diagnostic tool

What to check

Read all network and suspension-related DTCs with a capable scanner and record freeze-frame / ignition state
Check battery voltage and state of charge; repeat test with normal battery voltage
Inspect and test fuses and relays feeding the pneumatic suspension ECU
Visually inspect the ECU connector and harness for damage, corrosion, water ingress or rodents
Use scan tool to attempt to identify/poll the pneumatic suspension ECU; note if it appears on the network list
Check for related gateway or bus errors (other U-codes) that indicate a wider network problem

Signal parameters

Expected: ECU should appear on vehicle CAN/CAN-FD network and broadcast suspension messages at the vehicle-specific baud rate (commonly 250 kb/s or 500 kb/s depending on model)
Idle voltages (key ON, no activity): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (both near mid‑rail)
Dominant state (bus active): CAN_H rises ~1.0 V above idle and CAN_L falls ~1.0 V below idle (differential ~2.0 V)
No signal / no toggling on CAN_H/CAN_L at ECU connector indicates ECU not transmitting or bus open
Message IDs and signal contents are vehicle- and model-year specific—use manufacturer diagnostic/data lists

Diagnostic algorithm

Confirm code: Read all DTCs and note whether U1124 is current, pending, or history. Cycle key and see if code returns.
Attempt communication: Use OEM-level scan tool to poll the pneumatic suspension ECU. If tool reports 'module not present', continue with electrical checks.
Check battery and fuses: Verify battery voltage (≥12.4 V) and inspect/replace any fuses or relays for the air suspension ECU.
Power/ground verification: Backprobe ECU connector and confirm constant battery, switched ignition supply (if applicable) and a good ground reference.
Inspect connector/harness: Physically inspect pins for corrosion, bent pins or water damage; repair as needed.
CAN bus check: With key ON, measure CAN_H and CAN_L at ECU connector. If voltages are abnormal or static, check bus wiring continuity and resistance to neighbouring modules/gateway.
Isolate fault: If bus appears shorted, disconnect other modules one at a time (where safe) or remove suspect branch to find short/open. Use wiring diagrams to trace harness.
Check gateway/modules: Verify the gateway or other modules that should forward suspension messages are present and not reporting errors.
Re-test communication: After repairs to power, ground or wiring, attempt to communicate again with diagnostic tool and clear codes.
If wiring and supplies are good and no communication persists, consider replacement or repair of the pneumatic suspension ECU and follow OEM procedures for coding/programming.
After repair: Relearn/carry out any required module initialization and road-test to confirm correct suspension operation and no return of U1124.

Likely causes

Blown fuse or removed power/ground to the pneumatic suspension ECU
Connector unplugged or pins corroded/damaged at the ECU
CAN bus wiring open or shorted between ECU and gateway
Pneumatic suspension ECU internal failure

Fault status

⚠️ Status

No signal from pneumatic suspension ECU on the vehicle data bus — absence of communication.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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