Audio - Interference or Whine Noise From Generator
9232bmw01
Group 65
Radio and Accessories
Bulletin Number
65 02 92 (3471)
Woodcliff Lake, NJ
April 1992
Product Engineering
This Service Information bulletin supersedes the Service Information bulletin number 65 02 92 (3471) dated January 1992. Please remove and discard information bulletin number 65 02 92 (3471) dated January 1992 from your S.I. binder.
SUBJECT:
Radio Interference (Whine) from Generator
MODELS:
E31 /E32/E34
Situation:
Complaints of a slight whistling or whining noise from the radio when set at very low volume, especially noticed during periods of high battery current drain. (Generator harmonics high when items such as defogger grid, head lights, foglamps, etc. are switched on.) Noise tends to rise in frequency relative to engine RPM. The noise can often be heard on AM and FM bands as well as DISC setting if the car is equipped with a CD changer.
Solution:
A special 22,OOOuF filter capacitor has been developed to limit the amount of high-frequency power supply interference reaching the radio.
1. Make certain that other problems are not affecting the noise rejection of the radio.
^ Check the connections on the rear of the radio, and also check the connections of antenna coax cables at both ends.
^ Check the CD power and data cables if the car is so equipped.
^ In some cases, unapproved non-BMW accessories such as cellular phones and radar detectors have been wired poorly and act as an antenna, boosting the interference into the power supply of the radio. Disconnect all such aftermarket accessories and verify the problem still exists.
^ In some extreme cases it will be necessary to proceed with steps 2 and 3.
2. Assemble the capacitor.
^ Feed the small ring-terminal ends of the wiring harness through the nose of the rubber boot.
^ Attach the ring terminals to the capacitor body with the provided hardware.
^ Make sure the shark-tooth washers are between the capacitor and the ring terminal, and observe the correct polarity.
The polarity is stamped on the terminal end of the capacitor. The red wire is positive (+) and the brown is negative (-). Tighten the screws securely.
^ Slide the rubber boot over the end of the capacitor. The fit is very tight, and needle-nose pliers may be helpful.
^ Tie-wrap the waist and the nose of the boot to seal out moisture. Use a tie-wrap gun to secure ties for best fit.
3. Install the capacitor into the vehicle. Refer to illustrations for the best location.
^ Disconnect the vehicle battery, before attempting to install the capacitor.
^ Attach the red wire ring terminal to the stud on the bottom of the battery jumper terminal box.
^ The brown ring terminal should be connected to the large ground nut on the driver's side strut tower. Care should be taken to use the correct polarity, and make connections carefully to avoid sparks and potential damage.
^ Tie-wrap the capacitor body to the vehicle, referring to illustrations for mounting locations. Use a tie-wrap gun for secure fit.
Part
Information: Description Part Number
22,OOOuF Radio Capacitor Fit 12 31 9 059 399
Warranty
Status: Covered under the terms of the applicable BMW New Car Limited
Warranty.
Defect code 65 31 00 12 00
Labor operation 00 50 380
Labor allowance: 6 FRU