This Talend job shows how to read data from an external table in Google BigQuery and log the results. The simple usage of the tBigQueryInput component does not work because the access token needs to have additinal scopes:
https://www.googleapis.com/auth/bigqueryhttps://www.googleapis.com/auth/drivehttps://www.googleapis.com/auth/spreadsheets
The default component only has the first two.