U01BA

Code

Generic U — Network/User

Lost Communication With Park Lock/Pawl Control Module

Brand: Generic

Type: U — Network/User

Views: UK: 29 EN: 54 RU: 24

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Page language: EN

Causes

Faulty Park Lock/Pawl Control Module (internal failure)
Open/shorted/damaged wiring between module and vehicle network or power/ground
Corroded, bent or pushed-out connector pins at the module or junctions
Blown fuse or failed power supply to the module
Poor or missing ground at module chassis or harness ground point
CAN/LIN network fault (bus short, missing termination, bus-off node)

Symptoms

DTC U01BA present/active in control modules
Shift lever may not move to Park or vehicle may not detect Park position
Transmission may not lock into Park or parking interlock warning displayed
Starter inhibited or key cannot be removed if park interlock is not reported
Instrument cluster or shift indicator may show errors or amber warning lamp
Intermittent loss of communication — fault may be intermittent with vibration or temperature changes

What to check

Retrieve DTCs and freeze-frame data with a capable scan tool; note time, conditions, and related U- or B-codes
Check for other network communication codes (other U0xxx codes) which indicate a broader bus issue
Visually inspect connector at the Park Lock/Pawl Control Module and nearby harness for corrosion, damaged pins, or water intrusion
Check relevant fuses and relays for the module power feed
Verify module ground(s) are clean, tight, and corrosion-free
Wiggle harness/connectors while monitoring for communication loss or changes in live data

Signal parameters

Module supply voltage: approx. 11–14.5 V (battery/ignition on)
Ground resistance: < 1 ohm between module ground and chassis ground expected
CAN bus idle voltages (approx.): CAN_H ≈ 2.5–3.5 V, CAN_L ≈ 1.5–2.5 V (recessive ~2.5 V each; dominant shows ~+1V/-1V deviation)
CAN differential voltage when dominant: ≈ 1.5–2.5 V (system dependent)
Bus termination: ≈ 60 ohms across CAN_H–CAN_L (two 120Ω termination resistors in parallel)
Typical data rates: 250 kb/s or 500 kb/s (verify vehicle-specific rate)

Diagnostic algorithm

Connect a diagnostic scanner that can read U-codes and view live CAN network nodes; confirm U01BA is present and note related codes.
Check for patterns: does fault set with ignition state, engine off/on, or during cranking? Use freeze-frame and data logs.
Check fuses and relays for the Park Lock/Pawl module power circuit; replace if blown and retest.
Visually inspect module connector and harness for damage, corrosion, bent pins, or water intrusion. Repair or reseal as required.
With key on, measure module supply voltage and ground at the connector. If supply or ground is out of range, trace and repair power/ground circuit (check connectors, switches, fusible links).
Measure CAN_H and CAN_L at the module connector with key on and engine off. Compare to expected idle values and verify approx. 60 ohm termination across H–L. If voltages are incorrect, isolate short/open on the CAN pair.
Use a scope or high-speed CAN tool to verify differential signals and observe if the module transmits messages. If no messages from the module but supply and ground are good, the module is likely internally failed.
Wiggle test harness and connectors while watching live data for intermittent faults. Inspect and repair any intermittent sections.
If another node is bus-off, identify and repair that node; a single faulty node can disturb the entire network. Clear codes after repairs and confirm code does not return and normal operation is restored.
If wiring and network are good and the module still does not communicate, consult vehicle-specific wiring diagrams and consider module reprogramming or replacement per manufacturer procedures.

Likely causes

Failed module electronics (most common when power and CAN are present)
Damaged CAN pair or connector pins at the module
Missing module supply or ground (fuse, relay, or broken wire)
Bus-off condition from another node dragging the network down
Connector corrosion/water entry at module or associated junctions

Fault status

⚠️ Status

Lost Communication With Park Lock/Pawl Control Module — expected network messages from the module were not received. Check module power/ground, connectors, and CAN/LIN communication.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-4 hours