TC reported train moving slow speed around 2kph departing PNR2 in Auto mode. No fault indication andno circuit breaker tripped. TC proceeded in ATPM mode to JK N2 and was able to achieve target speed. TC switched back to ~~~~~ L3 3686 having slow pick-up. ER & LDL D/L & analysed. Found propulsion command given from VOBC but picked up on short period on train causing lost of command. Checked AMR-1/AMR-2/SR/CH4R/SIR no abnormalities. Found AMR-1 having high resistance fluctuation. Replaced AMR-1 with available spare.  Kana. 26/06/2021.    L3 3686 replaced AMR-2. Function check - OK.  Kana. 27/06/2021. L3 685/686 M/L test from UPD-JKN-UPD. During M/L test in 'AUTO' mode, both cab checked - OK. No fault indication/circuit breaker tripped during M/L test. No abnormalities found & train performance check - OK.  Hanafi. 28/06/2021.