HP QMS 1660 - Manual (Page 146)

Media Input
Options
QMS 1660 Print System Reference 6-8
9 Plug the paper feeder connector cable into the connector at
the back of the printer.
You moved this cable outside the paper feeder in step 6.
10 Replace the connector cover on the printer.
You removed this cover in step 3.
11 Reconnect the printer power cord and interface cables, and
then turn on the printer.
12 Replace the paper cassette you removed earlier, and install
the second cassette.
13 If you are using a legal/B4-size or an 11" x 17"/A3-size paper
cassette with the optional paper feeder, place the rear cassette
covers on both cassettes, one at the rear of the printer and
the other at the rear of the paper feeder.
Connector
Cable