Digital Radio Poor or No Reception
Diagnostic Instructions
Diagnostic Fault Information
Circuit
|
Short to Ground
|
Open/High Resistance
|
Short to Voltage
|
Signal Performance
|
B+ Voltage
|
-
|
1
|
-
|
-
|
Left Audio Signal (+)
|
2
|
2
|
2
|
-
|
Left Audio Signal (-)
|
2
|
2
|
2
|
-
|
Right Audio Signal (+)
|
3
|
3
|
3
|
-
|
Right Audio Signal (-)
|
3
|
3
|
3
|
-
|
Digital Radio Antenna Signal
|
B1259 02
|
4
|
4
|
-
|
Ground
|
-
|
1
|
-
|
-
|
1. No communication with Digital Audio Broadcast module.
2. No or distorted audio from left side speakers when listening to
digital radio.
3. No or distorted audio from right side speakers when listening
to digital radio.
4. Poor or no reception with Digital Audio Broadcast.
|
|
| |
Circuit/System Description
The Digital Audio Broadcast (DAB) radio receiver receives a
digital radio signal via the digital radio antenna. This signal is
passed to the DAB module through the digital radio antenna coax.
The DAB module sends a varying Alternating Current (AC) mV signal
through separate left and right audio circuits (+ and -) to the
radio. The voltage amount and rate of change is dependent upon the
type of signal being received. The radio then processes these
signals and passes the audio to the amplifier.
Reference Information
Schematic Reference
Radio/Navigation System Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Radio/Audio System Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Special Tools
EL 48028 Digital Radio Test Antenna
For equivalent regional tools, refer to
Special Tools .
Circuit/System Verification
| 1. |
Tune to a strong AM or FM
station and verify each speaker is producing clear and even sound,
with no distortion. |
| ⇒ |
If any speaker is not producing sound or the sound
produced is distorted, refer to
Speaker Malfunction . |
| 2. |
With the vehicle outside in an
area with an unobstructed view of the sky, tune to Digital Audio.
Verify reception is clear and audio is emitted from the A11
Radio. |
| ⇒ |
If reception is poor, refer to Digital Radio
Antenna Circuit Malfunction. |
| 3. |
A11 Radio tuned to Digital
Audio, use the radio balance function to transfer audio between the
left and right side of the vehicle. Verify clear and even sound is
heard from each side of the vehicle. |
| ⇒ |
If either side of the vehicle is not producing
sound or the sound produced is distorted, refer to Digital Radio
Output Circuit Malfunction. |
Circuit/System Testing
Digital Radio Antenna Circuit Malfunction
| 1. |
Ignition OFF, disconnect the
digital audio antenna coax from the A12 Digital Radio Receiver
Control Module. Connect the EL 48028 Digital Radio
Test Aerial to the A12 Digital Radio Receiver Control
Module. |
| 2. |
Radio ON, tuned to Digital
Audio, verify reception is clear and uninterrupted. |
| ⇒ |
If reception is not clear, replace the A12 Digital
Radio Receiver Control Module. |
| 3. |
Ignition OFF, reconnect the
antenna coax to the A12 Digital Radio Receiver Control Module,
disconnect the digital radio antenna coax from the T4H Digital
Radio Antenna. |
| 4. |
Ignition ON, test for 4.5-5.5
V between the antenna coax center terminal and the coax outer
shield. |
| ⇒ |
If not within the specified range, replace the
antenna coax. |
| 5. |
If all circuits test normal,
replace the T4H Digital Radio Antenna: |
Digital Radio Output Circuit Malfunction
| 1. |
Ignition OFF, disconnect the
X1 harness connector at the A11 Radio. |
| 2. |
Ignition ON, radio ON and
tuned to digital radio, test for a varying mV AC voltage reading
between the following signal circuit terminals listed below and
ground. |
| • |
Left audio signal (+) terminal
22 |
| • |
Left audio signal (-) terminal
8 |
| • |
Right audio signal (+)
terminal 21 |
| • |
Right audio signal (-)
terminal 7 |
| ⇒ |
If the varying mV AC voltage is not present, test
the signal circuit for a short to voltage, short to ground, or an
open/high resistance. |
| ⇒ |
If the circuit tests normal, replace the A12
Digital Radio Receiver Control Module |
| • |
If all circuits test normal,
replace the A11 Radio. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
Control Module References for radio and digital audio broadcast
module replacement, setup and programming
|
