Code
U131D
DS
U — Network/User
ASR+ selector signal fault: No signal
Views:
UK: 0
EN: 1
RU: 0
AI status
Completed
Completed
100%
Causes
- Open or short in wiring between ASR+ selector and receiving module (ABS/BCM/ECU)
- Loose, corroded or disconnected connector at the ASR+ selector or control module
- Failed ASR+ selector (switch or control unit)
- Faulty ABS/ESP or body control module that receives the selector signal
- CAN/LIN bus communication error or bus wiring fault
- Blown fuse or incorrect power/ground to selector circuit
Symptoms
- Inability to change ASR/traction mode or no response from ASR+ selector
- Traction control / ESP warning lamp(s) or message on dash
- Stored U131D fault (and possibly related network communication faults)
- ASR+/traction mode defaults to a single mode (fail-safe)
- Loss of related convenience functions that depend on selector input
What to check
- Retrieve full DTC list and freeze frame with a diagnostic scanner; note any other network codes
- Visual inspection: check ASR+ selector, connectors and wiring for damage, corrosion or water ingress
- Check relevant fuses and power/ground at selector connector
- Scan module inputs/messages: verify whether selector message appears on CAN/LIN (use module data list or bus monitor)
- Backprobe connector with multimeter/oscilloscope while operating selector to confirm signal changes
- Measure continuity/resistance between selector connector and receiving module with ignition off
Signal parameters
- Discrete-switch type: reference voltage typically ~5 V with low ~0 V when switched (verify on wiring diagram)
- CAN bus type: CAN High/Low idle ~2.5 V each; dominant state ~CAN_H 3.5 V / CAN_L 1.5 V — verify selector message ID appears on bus
- LIN bus type: single-wire serial communication (voltage and waveform will match LIN spec) — verify message presence
- Continuity: near 0 ohms between selector signal pin and receiving module pin (vehicle specific)
- Insulation: no short to battery positive or ground on selector signal circuit
Diagnostic algorithm
- Connect a capable scan tool and read all stored and pending DTCs; note related network or module faults.
- Clear codes, attempt to operate ASR+ selector and see if U131D returns and whether it is intermittent.
- Identify wiring diagram and pinout for the ASR+ selector and the receiving module (ABS/BCM/ECU).
- Inspect connectors visually and for secure fit; disconnect and inspect pins for corrosion or damage.
- With ignition on, backprobe the selector power, ground and signal pins. Confirm correct supply voltage and that signal changes when selector is operated.
- If the selector communicates via CAN/LIN, use a bus monitor to check for the selector message ID while operating the switch; verify bus voltage levels (idle and dominant) match spec.
- If no signal at module, test continuity between selector connector and module connector with ignition off; repair any opens or shorts found.
- Repair or replace damaged wiring, terminals or connectors. If wiring and connectors are good, replace the ASR+ selector switch and retest.
- If selector and wiring OK but message still absent, investigate receiving module (ABS/ESP or BCM) — test its inputs and CAN/LIN interfaces; consider software update or module replacement as last resort.
- After repairs, clear codes, verify correct operation of selector and confirm no reoccurrence of U131D.
Likely causes
- Connector corrosion or loose terminal at selector or receiving module
- Broken or pinched wiring in harness between selector and module
- Faulty selector switch (mechanical or internal electrical failure)
- Intermittent CAN/LIN bus fault preventing message transfer
Fault status
Status
No signal received from ASR+ selector. Communication or input to receiving control module absent or interrupted.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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