What was found
LH BLEED TRIP OFF LIGHT ILLUMINATED AFTER PUSH BACK. GROUNDED - YES. CREW REPORTED LH BLEED TRIP OCCURRED IMMEDIATELY AFTER CRANKING/START SW TO GND #1. INIT MX ABLE TO DUPLICATE BUT AFTER SUBSEQUENT ATTEMPTS BLEED TRIP DID NOT OCCUR DURING START CYCLE. INIT OCCURRED BEFORE ANY ENG ROTATION CKD CONTINUITY RESISTANCE OF S20 #1 BLEED O/T SW AND #1 BAR PRESS SW REF SSM 36-11-11 FROM DP1102/BAR WITH #1 ACAU REMOVED SEE DEFECT 60190516. REMOVED & REPLACED #1 BAR AS PRECAUTION REF B737-800 AMM 36-11-03 4 MIG 51A INST & RMVD OPS & LK CK GOOD.