Audio Problems - Diagnosis
ClassificationEL92-012
Section
Electrical
Models:
1991-92 M30 Convertible
Reference:
TECHNICAL BULLETIN ITB92-060
Date:
November 5, 1992
DIAGNOSIS OF AUDIO PROBLEMS: "SC-1" DISPLAYED ON THE HEAD UNIT
APPLIED MODELS:
1991-92 M30 Convertible
Year Model Audio System Head Unit P/N
'91-92 M30 Convertible Clarion Active Speaker System PP94801A
SERVICE INFORMATION:
The "SC-1" display, on head units, indicates a short circuit located in the speaker assembly(ies) or in the wiring/harness/connector assembly from the head unit to the speaker. This is a protection circuit for the head unit. It is important to remember that there is usually no fault with the combo head unit. The "SC-1" display usually indicates a defective speaker or pinched wire in the harness leading to the speakers or door jam connections.
TROUBLESHOOTING:
1. After removing the head unit from the dash, disconnect the speaker harness connector and main harness from the head unit. With the ignition key turned to the "on" position, measure the voltage between each of the speaker output wires and the vehicle chassis ground under the following conditions:
^ Wiper and washer switch cycled on and off.
^ Turn signals and hazard light cycled on and off.
^ Rear window defogger cycled on and off.
^ Doors opened and shut.
^ Brake light activated.
The voltage should be "zero". If voltage is measured, then, a problem exists within the related condition tested. Speaker connections to ground should also be verified for continuity.
2. Measure the resistance value - between the signal ground line and signal power line - of each speaker. The value should be 3 - 10 ohms. If the value is below 1 ohm, the speaker has a problem.
WARRANTY INFORMATION:
Operation Opcode PNC CS CT FRT
Repair Wiring Harness RA16AA (*) 4Q 39 S/T
(*) Select the appropriate harness PNC in Section "RA".
OR
For replacement of any speaker determined to be defective, select the appropriate PNC/OpCode/FRT combination from the Main/Sub-Code Section "RN" in the 1993 Warranty Flat Rate Manual.
SPECIAL NOTE CONCERNING AFTERMARKET WIRING MODIFICATIONS:
Aftermarket connections to the speaker output of the head unit may also cause an "SC-1" display and a no head output condition. Examine the vehicle for aftermarket amplifiers, equalizers, and CD autochangers.
NOTE:
Repair of aftermarket connections which may have caused an "SC-1" display are not covered by the Infiniti Warranty.