DTC U0001-81: HS CAN Communication Bus - Invalid serial data received: Action

NOTE: Do NOT replace any module's just on the basis of this DTC .

Using the JLR approved diagnostic equipment, read the Data IDentifier (DID) D020 and check the snapshot data to determine the missing message source control module (REFER to the DID D020 TABLE ), check other modules for the same DTC indicating a fault in the wiring harness and/or incompatibility in the software versions.
NOTE: During this step, make sure that the battery support unit is NOT connected.

Using the JLR approved diagnostic equipment, check Live Data - Main ECU Voltage Supply (0xDD02) - Vehicle Battery Voltage (0x402A). When the vehicle is stationary, move the steering from lock to lock in 2 seconds, immediately within 10 seconds from engine crank. If the main PSCM voltage drops below 8.0 volts during the steering test, then install a new battery. Refer to: BATTERY .
Using the JLR approved diagnostic equipment, check Live Data - Main ECU Voltage Supply (0xDD02) - Vehicle Battery Voltage (0x402A). Refer to the appropriate information of the service information and check the battery and charging system. Rectify as necessary. Refer to: CHARGING SYSTEM .
GO to Pinpoint Test B. check the PSCM power and ground circuits and associated connectors for open circuit, high resistance. Repair or replace circuit(s)/connector(s) as required. If the wiring harness checks are OK, check the HS CAN Bus (chassis) wiring harness to PSCM GO to Pinpoint Test C. .
NOTE: Do NOT replace the steering gear.

If the fault persists and cannot replicate network issue, contact the JLR Technical Helpdesk.