Radio - AM Band Whining When Brake Pedal Depressed
GROUP 65Sound System, Cruise, Alarm
65 06 00
Woodcliff Lake, NJ
May 2001
Service Engineering
SUBJECT
E46 Convertible - 3rd Brake Light Induced Whine on AM Band
MODEL
E46 convertible, produced up to 11/00
SITUATION
A whining noise may be heard on AM band stations, when the brake pedal is being depressed.
CAUSE
Interference from the third (neon) brake light, caused by the insufficient grounding of the trunk lid.
(The trunk lid is grounded through both hinges. Due to paint over-spraying, or an excessive amount of lubrication the resistance of the ground path could exceed the limits).
CORRECTION
On a customer complaint basis, and after verifying the complaint, install additional ground strap for the trunk lid.
PROCEDURE
1. Produce one ground wire strap (as shown on the illustration).
The required shop materials include:
- two 12-10AWG ring connectors (e.g. AMP 12-10 ring connector; ID=3/8", OD=5/16")
- one 20" piece of stranded 12 AWG (2.5 sq.mm) insulated wire
2. Remove 10 plastic fasteners for the trunk lid liner.
3. Remove two Phillips screws (1) securing the tool storage tray.
4. Remove trunk lid liner with tool storage tray.
5. Using a 1/8" drill bit, drill a hole in the inner frame of the trunk lid in the location indicated on the illustration (above, and to the left of the electrical harness opening).
6. Using appropriate sheet metal screw (1) (e.g. Phillips 10x3/8 short, pan-head sheet metal screw), secure one end of the ground strap to the trunk lid.
7. Route the ground strap through the rubber boot (2) along the electrical harness for the trunk lid.
8. Remove liner material from the right rear corner of the trunk. Attach the other end of the ground strap (1) to the ground splice (2) as shown on the illustration.
9. Reinstall all removed components.
PARTS INFORMATION
WARRANTY INFORMATION
Covered under the terms of the BMW New Vehicle Limited Warranty.
DISCLAIMER