Speaker - Thump Noise on Brake Application
07/03/9786/04/97/NAS
Issue 2
SUBJECT
Speaker Thump Noise
MODEL
Discovery
AFFECTED VEHICLES
LP
LH
LJ 1997 MY
LD
DETAIL
Land Rover has determined that some 1997 Discovery radios may have incorrect wire connections at the main amplifier connector C2054. The incorrect wiring results in audio noise when the brake light circuit is energized.
A distinct "thump" noise is heard from radio speakers upon brake application (most noticeable when the radio volume is TURNED DOWN).
ACTION REQUIRED
Upon customer complaint for the symptoms outlined perform the specified repairs.
PARTS INFORMATION
Tool:
^ Digital Multi-Meter
PROCEDURE
Perform the diagnostic procedures and repairs outlined in the following pages for the repair of Speaker Thump Noise.
WARRANTY
Normal warranty procedures and policies apply.
COMP. CODE
SR0
86.50.89/29 - Time 0.55 hr.
Repair amplifier connector wiring
Inspection:
1. Remove glove box to access the main audio amplifier.
2. Inspect the black wires in cavity 11 of connector C2054 on the main audio amplifier and determine which of the following condition exists (Figure 1):
A) The black wire in cavity 11 is part of port installed add-on harness (not the vehicle wiring hamess). (This is the correct configuration).
B) The black wire in cavity 11 is part of the vehicle harness.
3. If condition B is present perform the following repair.
Repair:
1. Remove vehicle harness black wire from cavity 11. (Figure 2).
NOTE:
Accessory harness black wire is probably incorrectly installed in cavity 12 of the connector.
1. Install the black accessory harness wire into cavity 11.
2. There will now be one connector location (Cavity 12) and two free black wires in the vicinity of connector C2054.
^ One wire is the signal wire for the sub-woofer speakers which is to be installed in cavity 12.
^ The other is an unused ground wire replaced by the accessory wire harness: This wire is to be left UNCONNECTED.
3. Locate connector C437 in the right end door jam.
4. Using a Digital Multi-Meter, verify which of the two black wires is connected C437, cavity 2.
5. The wire which has continuity to C437 is the subwoofer signal wire.
6. Install sub-woofer wire in C2054, cavity 12 (Figure 2).
7. Verify that the speaker "thump" is no longer present when the brake light circuit is activated.