Audio System - Poor AM Band Reception
S801999-
Section
3
Group
39
No.
0018
Year
04
Month
02
Diagnostics for radio reception on the AM waveband
Background
Before carrying out diagnostics and fault-tracing according to this Service Bulletin, see Tech Net Note 39-35 dated 4-3-2003.
This Service Bulletin describes how to carry out diagnostics, fault-trace and to remedy poor AM radio reception.
Important!
Read the following information before carrying out diagnostics.
Affected Vehicle
Model Factory Chassis No.
S80 1 000570-
Material
Description Quantity P/N
Antenna cable 1 9438707
Tape 0,5m 9128331
Tie strap 2 983750
Special tool
Description Reference to Tool Bulletin P/N
Terminal removal tool, White From Terminal repair kit 951 2639
9512946 or 9512647 (STB 95)
Radio equipment AM radio diagnostics, reception
Design and Function 1
AM reception is received via the integrated antenna above the rear windshield heating loops.
The antenna is connected to an antenna amplifier positioned on the left-hand C-post.
The FM waveband uses a diversity system consisting of two antennas. One of the diversity system antennas is integrated in the rear windshield heating loops, the other is in the rear bumper.
Only cars with factory-installed radios have an antenna amplifier for the diversity system. After market accessory radios may require installation of an after market accessory antenna amplifier for the diversity system for interference free FM reception.
Weak AM reception and/or reception of more than one station at a time 2
RECEPTION TEST
A "reception test" must be carried out before and after the diagnostic procedure to ensure the AM signal is received properly by the radio. The diagnostic procedure can lead to play or poor connection in a remedied connector.
If it is necessary to carry out a repair, a "reception test" must be carried out afterwards.
The purpose of the "reception test" is to compare "the test vehicle" with a similar Volvo vehicle, equipped with the same model of radio and antenna in the rear windshield, WITHOUT AM waveband reception problems.
The vehicles must be parked beside each other outdoors at least 30 meters away from buildings or any other constructions that might block the radio signals.
AM waveband reception quality changes dramatically in the hours around dusk and dawn. Take care when comparing a result obtained at dusk and/or dawn with a result obtained at another time of day.
Start by finding the first clear audible radio station furthest down on the AM waveband in a "similar" vehicle. Use the search button and note all clear, audible radio stations. Repeat the same test procedure in the "test vehicle" and compare the number of received stations.
Note!
Certain types of tinted film applied to the rear windshield can block the antenna signals (this applies to special lighter tinted films which contain metal particles). If tinted film has been applied: Check that the antenna wire in the rear windshield is not cut.
Diagnosing fault causes for weak AM waveband reception
Checking connections around the C-post 3
Weak AM waveband reception is often caused by poor connections or a faulty antenna cable.
Note!
Always carry out a reception test after a repair.
Listen to a weak radio station on the AM waveband whilst carrying out the diagnosis.
Remove the C-post panel. See VADIS:
Repairing and installing
Function group 85
Bend the antenna cable (1) at the amplifier terminal.
If the speakers crackle when bending the antenna cable:
- Remedy according to SB390029: Improved radio reception, installing brass mountings.
If no interference is heard:
- check the antenna amplifier power supply (2) and ground terminal (3)
- check the cable from the amplifier to the rear windshield (4). Check for damage or loose connections.
If no faults are found, continue to the next stage.
Checking connections, continued 4
Check that connector (4) is connected correctly to the rear windshield. Check that the AM cable positioned at the uppermost point is marked with a white dash. Check that the text is pointing towards the rear windshield.
Check terminal (4), which is similar to a 9 Volt battery terminal. Check for oxidation.
Disconnect the connector. Check the mating surfaces. If the connecting sockets are deformed, adjust using pliers.
If the repair is unsuccessful, replace the antenna amplifier.
Checking the tinted film on the rear windshield 5
If tinted film is applied to the rear windshield, check the antenna wires for damage and adhesion.
Ask the customer if the application of tinted film affected AM waveband radio reception.
It may be necessary to remove the tinted film for the antenna to function properly.
On S80 cars with chassis numbers 000570-063999 6
Check the connector (1) under the rear seat at the C-post mounting.
Bend the coaxial cable on both sides of the connector
If no faults are found, continue to the next stage.
If a fault is found, carry out steps 10-13.
All cars 7
Check that the cable is not deformed.
If the coaxial cable is trapped the capacitance of the cable may change.
Even if there is no visible damage a slight kink in the cable can cause radio interference.
If no faults are found, continue to the next stage.
Resistance measurement 8
Measure the resistance between the FM antenna terminal pin (1) (the lower) on the rear windshield and the antenna amplifier ground (2).
The value should be 7-14 Ohm.
The AM antenna terminal pin (upper) is not connected to ground. The value must be infinite.
If no faults are found, continue to the next stage.
Routing a new antenna cable for a comparison test 9
This test is intended for cars with chassis nos. -064000
Remove:
- the radio. See VADIS:
Repairing and installing
Function group 39
Audio, radio equipment, Radio telephone
- the antenna cable (1) to the radio (2). Connect an antenna cable between the radio and the antenna amplifier on the C-post.
Carry out another reception test to ensure that reception has improved.
If reception:
- has improved, replace the antenna cable on the left-hand side. See stage 10-13: Antenna cable, replace
- has not improved, try another amplifier on the C-post.
Antenna cable, replace 10
Remove the secondary lock from the antenna cable connector which is connected to the radio.
Note!
The original coaxial cable on the left-hand side cannot be removed from the vehicle.
Antenna cable, replace, continued 11
Disconnect the right-hand antenna cable from the connector
Bend the catch (1) upwards. Remove the cable using Terminal Removal Tool 9512639.
Connect the right-hand antenna cable to the new replaced left-hand antenna cable connector.
Cut off or secure the old antenna cable on the left-hand side to prevent rattles.
Antenna cable, replace, continued 12
Remove the combined instrument panel, see VADIS:
Repairing and installing
Function group 38
Combined instrument panel, Replacing
Route the antenna cable from the radio up to the cable duct (1) behind the combined instrument panel.
Loosely install the radio. Wind foam rubber P/N 9128331 around the cable.
Secure the antenna cable to the cable duct using two tie straps.
Antenna cable, replace, continued 13
Remove:
- the hood catch mechanism. See VADIS:
Repairing and installing
Function group 82
Hood, hood catch mechanism
- sill trim panel, see VADIS:
Repairing and installing
Function group 84
Front and rear sill trim panel.
Route:
- the antenna cable next to the existing wiring down to the door sill
- the antenna cable next to the cable ducts inside the door sill to the antenna amplifier on the C-post.
Note!
Route the antenna cable all the way to the antenna amplifier on the C-post before securing using tie straps.
Secure the antenna cable to the existing cable harness and cable ducts. Use tie straps.
Reinstall the radio, the combined instrument panel and sill trim, the hood catch mechanism and the C-panel.
WARRANTY STATEMENT:
Claims may be submitted under the New Car Warranty when there is a documented customer complaint, using claim type 01.