Thanks you very much for this "hard to find" service manual.
Will help a lot in repairing this tuner.
Text excerpt from page 18 (click to view)
GM-X352
Connection Diagram
Fuse (30 A) Special red battery wire [RD-223] (sold separately) After making all other connections at the amplifier, connect the battery wire terminal of the amplifier to the positive (+) terminal of the battery. Fuse (30 A) Ground wire (black) [RD-223] (sold separately) Connect to metal body or chassis.
Grommet
Connecting wires with RCA pin plugs (sold separately).
Car stereo with RCA output jacks
External Output
Front side
RCA input jack
Speaker input terminal
Back side Fuse (20 A)
Speaker output terminal
System remote control wire (sold separately) Connect the male terminal of this wire to the system remote control terminal of the car stereo (SYSTEM REMOTE CONTROL). The female terminal can be connected to the auto-antenna relay control terminal. If the car stereo does not have a system remote control terminal, connect the male terminal to the power terminal through the ignition switch.
