Principles of Operation
A fluctuating AC voltage audio signal is sent to the speakers directly from the audio unit to reproduce sound. The audio unit has a self-diagnostic mode that can be entered by pressing preset buttons 3 and 6 simultaneously.
Normal Operation
The audio unit receives power on circuit 137 (YE/BK) (hot in RUN/ACC) and circuit 956 (OG/LG) (hot at all times). The audio unit is grounded on circuit 694 (BK/LG). A redundant ground is added on circuit 57 (BK) for all but the Mach 300 audio systems. With the ignition switch in the RUN/ACC position, all of the features are operational.
The radio antenna receives AM and FM radio waves. The radio waves are sent to the audio unit through the radio antenna lead-in cable. The radio suppression equipment reduces engine ignition and electrical systems interference transmitted through the speakers.
When installing any new radio suppression equipment components, make sure that a good contact is made at all connections. Remove any paint or dirt from between a component and its ground. Tighten all connectors and screws securely according to the torque specifications.
The radio antenna receives AM and FM radio waves. The radio waves are sent to the audio unit through the radio antenna lead-in cable. The radio suppression equipment reduces engine ignition and electrical systems interference transmitted through the speakers.
When installing any new radio suppression equipment components, make sure that a good contact is made at all connections. Remove any paint or dirt from between a component and its ground. Tighten all connectors and screws securely according to torque specifications.
The audio unit directs the audio signals to the speakers through separate positive and negative circuits for each of the 4 audio channels: LH front, RH front, LH rear, and RH rear. The audio unit provides internal circuit protection for shorts to ground, shorts to B+ battery, or shorts between any output circuits.
The subwoofer speaker is powered by a separate subwoofer amplifier. The START input circuit, 174 (GY/BK), carries out 2 functions: to turn on the subwoofer amplifier, and to indicate to the audio unit when the subwoofer output distortion signal reaches a damaging level. The audio unit then reduces the audio output signal to the subwoofer amplifier. The subwoofer amplifier receives power on circuit 720 (RD/YE), and ground on circuit 694 (BK/LG).
The START input circuit 1786 (BN/PK) is sent to the audio unit when the ignition switch is turned to the START position. The audio unit then immediately mutes all speaker amplifier outputs and the subwoofer amplifier enable circuit output to eliminate the possibility of speaker pops during engine cranking.
The audio unit receives power on circuit 137 (YE/BK) (hot in RUN/ACC) and circuit 956 (OG/LG) (hot at all times). The audio unit is grounded on circuit 694 (BK/LG). With the ignition switch in the RUN/ACC position, all of the features are operational.
Circuit 956 (OG/LG) is a constant battery B+ supply to the CD changer. Circuit 694 (BK/LG) is the CD changer ground circuit. Circuit 856 (VT) and circuit 833 (TN) are the audio control protocol (ACP) communication network circuits between the audio unit, CD changer, and the audio control protocol (ACP) module. Circuit 1068 (LG/BK) is the power on signal from the audio unit to the CD changer and the ACP module. Circuit 799 (OG/BK) and circuit 798 (LG/RD) are the left channel audio circuits between the CD changer and the audio unit. Circuit 832 (LB/PK) and circuit 690 (GY) are the right channel audio circuits between the CD changer and the audio unit.
Circuit 956 (OG/LG) is a constant battery B+ supply to the CD changer. Circuit 694 (BK/LG) is the CD changer ground circuit. Circuit 856 (VT) and circuit 833 (TN) are the audio control protocol (ACP) communication network circuits between the audio unit, CD changer, and the audio control protocol (ACP) module. Circuit 1068 (LG/BK) is the power on signal from the audio unit to the CD changer.
The radio antenna receives AM and FM radio waves. The radio waves are sent to the audio unit through the radio antenna lead-in cable. The radio suppression equipment reduces engine ignition and electrical systems interference transmitted through the speakers.
When installing any new radio suppression equipment components, make sure that a good contact is made at all connections. Remove any paint or dirt from between a component and its ground. Tighten all connectors and screws securely according to torque specifications.
The audio unit directs the audio signals to the speakers through separate positive and negative circuits for each of the four audio channels: LH front, RH front, LH rear, and RH rear. The audio unit provides internal circuit protection for shorts to ground, shorts to B+ battery, or shorts between any output circuits.
The subwoofer speaker is powered by a separate subwoofer amplifier. The START input circuit, 174 (GY/BK), carries out two functions: to turn on the subwoofer amplifier, and to indicate to the audio unit when the subwoofer output distortion signal reaches a damaging level. The audio unit then reduces the audio output signal to the subwoofer amplifier. The subwoofer amplifier receives power on circuit 720 (RD/YE) and ground on circuit 694 (BK/LG). Audio signals are received by the audio unit through circuits 169 (LG/BK) and 172 (LB/RD).
The START input circuit 1786 (BN/PK) is sent to the audio unit when the ignition switch is turned to the START position. The audio unit then immediately mutes all speaker amplifier outputs and the subwoofer amplifier enable circuit output to eliminate the possibility of speaker pops during engine cranking.
The radio suppression equipment reduces engine ignition and electrical systems interference transmitted through the speakers. When installing any new radio suppression equipment components, make sure that a good contact is made at all connections. Remove any paint or dirt from between a component and its ground. Tighten all connectors and screws securely according to torque specifications.