Radio - AM Reception Diagnostics
S801999-
Section
3
Group
39
No.
0018
Year
01
Month
01
S80 AM radio reception diagnostics
Background
This Service Bulletin explains how to diagnose and fault trace causes of poor AM radio reception.
Remedy all reception faults before attempting to diagnose any apparent electrical interference to AM radio reception in accordance with Service Bulletin 39-0025.
Important!
Read before you start diagnosing.
Material:
S80 AM radio reception diagnostics AM radio diagnostics, reception
1
Function and design
The AM band has 1 antenna. The wire connects to the amplifier located on the left side D pillar and uses part of heater grid in the rear window as the antenna.
The FM band uses a diversity system consisting of 2 antennas:
The Main antenna wire is shared with the AM band and connects to the amplified located on the left side D pillar. The main antenna is a separate grid in the in rear window.
Factory mounted radio:
The Sub antenna wire is routed down the right side of the interior and connects to an amplifier located near the rear bumper. The sub antenna is mounted at the rear bumper.
2
Weak reception and/or multiple station heard simultaneously
SEEK TEST
A "seek test" should be done at the beginning and the end of diagnostic procedure to establish if the AM signal is being properly received by the radio. The diagnostic procedure may result in the correction of a poor connector contact.
If any repair is necessary, a seek test should also be done after the repair.
The purpose of a seek test is to compare the "test" vehicle to a "similar" Volvo vehicle with the same radio model and window antenna with no AM reception complaints. Both vehicles should be parked next to each other outdoors at least 100 ft. away from buildings or other structures that may block radio signals. The form provided should be used to document the number of stations received. AM reception quality changes dramatically within 2 hours of sunrise or sunset. Be careful when comparing results taken around sunrise or sunset to results take at different times of day.
Begin with the "similar" vehicle by selecting the lowest clearly audible AM station. Use the seek button and document all clearly audible stations available. Then repeat the test with the "test" vehicle and compare the number of stations found.
Note!
Certain types of window tint films applied to the rear window can disrupt antenna signals (especially lighter tints that contain metal particles). If window tint film is applied: Check that window antenna is not cut.
3
General Static/crackling noise (helicopter noise)
Chassis - 116810
If a seek test gives the same number of clearly audible stations but a "helicopter" sound is heard in the "test" vehicle, the AM quality may be improved by replacing the interior light housing. The new interior light housing has additional grounding for UEM.
UEM processor sound being heard in the audio system. UEM has a long ground wire which in some cases can act as an antenna. In certain cases the AM quality may be improved by replacing the interior light housing complete. The new interior light housing has an additional grounding for UEM. (see SB 39-0025).
4
Intermittent pulsing, buzzing sound with seat heater on
Chassis no 0029668-147860
A pulsing, buzzing noise may be heard from the radio on AM frequency if seat heater is activated. If there is a complaint from the customer, an adapter cable with a 180-Ohm resistor must be connected in series to control module for the seat heater as a service solution. One adapter cable must be used for each seat. (See SB39-0025)
5
Radio noise at 6-8 MPH on AM
Chassis - 49149
See Service Bulletin 39-0010
Diagnosing the cause of weak AM reception
6
Checking connections in the D pillar area
The cause of weak AM reception can usually be traced to a poor connection or faulty antenna wire.
Note!
Always perform Seek test after any repair.
Listen to a weak AM station while doing the diagnostics.
- Remove D pillar panel trim. See VADIS, 8, 85 Interior, Panels, C/D panel.
- Wiggle the antenna cable (1) at the connection to the amplifier.
- If a crack or bang is heard in the speaker, install new AUM to D pillar antenna cable
If no noise is heard:
- Check power(2) and ground screw (3) to antenna amplifier.
- Check wire from the amplifier to rear window (4) for damage or poor connection.
- If OK, continue with next step.
7
- Check that the connector (4) is assembled correctly on the rear window, AM wire on top marked with a white stripe and the text on the connector must be facing the rear window.
- Check for corrosion on the 9V style battery connector (4). Remove the connector and inspect. If the connector inserts are deformed, try to adjust with pliers. If repair is not successful, install new antenna amplifier.
- If OK, continue with next step.
- If the coax cable (1) is only lightly distorted or kinked, try to re-shape the cable with a pair of pliers. If not possible, install a new antenna cable,
8
- Check for tinted films on rear window. If tinted film is applied, check that window antenna is not cut off or damaged. Ask customer if the tinted film had any effect on AM reception. The tinted film may need to be removed for the antenna to function correctly.
9
On S80 cars up to chassis number 64000
- Check under the rear seat in the base of the D-pillar for connector(1).
- Wiggle the coax wire on both sides of the connector.
- If OK, continue with next step.
- If not OK, perform step 10 and continue with step 12.
10
All cars
- Check wire for signs of deformation. Pinching can change capacitance of coax wire. Although no damage is done a slight kink could disrupt the AM signal transfer from antenna to AUM.
If OK, continue with next step.
- Measure the resistance between FM (bottom) pin (1) on the rear window and ground screw (2). The value should be 7-14 Ohms = OK.
- The AM (upper) pin is not grounded. The value should be=- (infinity)
- If OK, continue with next step.
11
Route new antenna cable for comparative test. This test is primarily for cars up to chassis no -64000
- Remove the radio. See VADIS, 3, 39 Audio, Radio equipment, Radio Carphone.
- Remove the antenna wire (1) from AUM (2).
- Connect a test antenna cable between AUM and D pillar amplifier. Perform another seek test to see if reception has improved.
- If yes, replace left side antenna cable. See step 13-16. Replacing antenna wire.
- If no, try with another the D pillar amplifier.
12
Replacing antenna wire
Remove secondary lock from the antenna cable connector connected to the radio.
Note!
The original left side coax cable will not be removed from the vehicle.
13
- Remove the right side antenna wire from the connector. Bend the lock (1) upwards and remove the wire.
- Install the right side antenna wire in the connector of the replacement left side antenna wire.
- Cut the old US antenna wire or secure it to prevent rattling.
14
- Remove the combined instrument. See VADIS 3, 38 Instrumentation, Replacement of components in combined instrument.
- Route the antenna wire from the AUM up to the wire channel (1) behind the combined instrument.
- Install the AUM loose. Wrap cable with plastic foam p/n 9128331.
Note!
Route the antenna wire all the way to the D pillar amplifier before securing it with strip clamps.
Secure the antenna cable to the wire channel with two strip clamps.
15
- Remove Hood lock control, see Vadis 8, 82, Hood, Hood lock control.
- Remove Sill trim panels, see Vadis 8, 85, The front sill trim panel/The rear sill trim panel.
- Route the antenna wire beside the existing wires down to door sill.
- Route antenna wire beside wire channels inside door sills up to D-pillar amplifier.
- Secure the antenna wire to existing wires and wire channels with strip clamps.
- Reinstall AUM, combined instrument and panels.
16
S80 AM Radio Seek Test Worksheet
Please use the worksheet to document the results of the AM seek test.
The "TEST" vehicle is the customer car and the "SIMILAR" vehicle is a known good comparison car.
After repairs the number of clear AM stations should be approximately the same for both vehicles.
WARRANTY STATEMENT: Claims may be submitted under the New Car Warranty when there is a documented customer complaint, using claim type 01.