Pinpoint Test A: Poor Reception - AM/FM
Information and Entertainment System
Pinpoint Test A: Poor Reception - AM/FM
Refer to Wiring Diagram Set 130, Audio System/Navigation for schematic and connector information Electrical Diagrams.
Normal Operation
The AM/FM antenna receives AM and FM radio waves and transmits them to the Audio Control Module (ACM) through the AM/FM antenna cables. The ACM (Audio Control Module) powers the AM/FM antenna to amplify the AM signal.
The RDS function allows the vehicle operator to choose which genre (category) of music to listen to. When the SCAN button is pressed, the ACM (Audio Control Module) only stops at channels falling within the selected category. If no channel in the selected category is found, the ACM (Audio Control Module) continues to scan without stopping. This may appear to be a reception issue, but it is actually due to the customer setting.
- DTC B1A56:21 (Antenna: Signal Amplitude< Minimum)- sets when the signal strength is less than the pre-configured threshold value during the ACM (Audio Control Module) self-test. This DTC applies to vehicles with navigation only.
This pinpoint test is intended to diagnose the following:
- No channel found in the selected category
- Wiring, terminals or connectors
- AM/FM antenna
- AM/FM antenna cable
- Charging system
- Ignition system
- ACM (Audio Control Module)
PINPOINT TEST A : POOR RECEPTION - AM/FM
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
A1 CHECK THE RDS SETTING
- Turn the RDS function off. Refer to the Owner's Literature.
- Scan for a good channel.
Does the audio system find a good channel with normal reception?
Yes
The system is operating correctly. The concern was a result of no channel being found in the selected category.
No
GO to A2.
A2 CHECK THE AUDIO SYSTEM RECEPTION
- Check the audio system reception with the engine running, and with the engine off.
Does the poor reception only occur with the engine running?
Yes
GO to A3.
No
GO to A5.
A3 CHECK THE GENERATOR
- Ignition OFF.
- Disconnect: Generator C102A.
- Start the engine.
- Operate the audio system in radio tuner (AM/FM) mode.
Is the reception OK?
Yes
INSTALL a new generator. TEST the system for normal operation.
No
GO to A4.
A4 CHECK THE IGNITION CIRCUITS
- Ignition OFF.
- Connect: Generator C102A.
- Check the ignition circuits for correct routing, grounding, and integrity of the connections.
Are the ignition components OK?
Yes
USE a jumper cable to ground various parts of the vehicle to the frame (for example: engine, fenders, quarter panels, stone deflectors, air cleaner, body sheet metal). When the noise is eliminated, PROVIDE a permanent ground where necessary. TEST the system for normal operation.
No
REPAIR the ignition system as necessary. TEST the system for normal operation.
A5 CHECK THE ANTENNA ENABLE SIGNAL
- Ignition OFF.
- Disconnect: AM/FM Antenna C2086.
- Ignition ON.
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the voltage between the AM/FM antenna C2086-2, circuit CME44 (YE/GN), harness side and ground.
Is the voltage greater than 10 volts?
Yes
GO to A7.
No
GO to A6.
A6 CHECK THE AM/FM ANTENNA ENABLE CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Disconnect: ACM (Audio Control Module) C240A.
- Measure the resistance between the ACM (Audio Control Module) C240A-2, circuit CME44 (YE/GN), harness side and the AM/FM antenna C2086-2, circuit CME44 (YE/GN), harness side; and between the ACM (Audio Control Module) C240A-2, circuit CME44 (YE/GN), harness side and ground.
Is the resistance less than 5 ohms between the ACM (Audio Control Module) and the AM/FM antenna, and greater than 10,000 ohms between the ACM (Audio Control Module) and ground?
Yes
GO to A9.
No
REPAIR the circuit. TEST the system for normal operation.
A7 CHECK THE AM/FM ANTENNA CABLE
- Ignition OFF.
- Disconnect: AM/FM Antenna Cable At AM/FM Antenna.
- Disconnect: AM/FM Antenna Cable In-Line Connection At RH Kick Panel.
- Disconnect: AM/FM Antenna Cable At ACM (Audio Control Module).
- Measure the resistance of the upper AM/FM antenna cable core between the antenna and the lower AM/FM antenna cable; and between the upper AM/FM antenna cable core and shield.
- Measure the resistance of the lower AM/FM antenna cable core between the ACM (Audio Control Module) and the upper AM/FM antenna cable; and between the lower AM/FM antenna cable core and shield.
Is the resistance of each AM/FM antenna cable core less than 2 ohms, and the resistance between the core and shield of each AM/FM antenna cable greater than 10,000 ohms?
Yes
GO to A8.
No
INSTALL a new upper or lower AM/FM antenna cable, as necessary. REFER to Antenna Cable - AM/FM/Satellite Radio . CLEAR any DTCs present. TEST the system for normal operation.
A8 ISOLATE THE ANTENNA
- Ignition OFF.
- Connect: AM/FM Antenna Cable In-Line Connection At RH Kick Panel.
- Connect: AM/FM Antenna Cable At ACM (Audio Control Module).
- Install a new AM/FM antenna. Refer to Antenna- AM/FM/Satellite Radio .
- Operate the audio system in radio tuner (AM/FM) mode.
Is the reception OK?
Yes
The cause of the concern was an inoperative AM/FM antenna. The system is now operating correctly.
No
GO to A9.
A9 CHECK FOR CORRECT ACM (Audio Control Module) OPERATION
- Ignition OFF.
- Disconnect all the ACM (Audio Control Module) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the ACM (Audio Control Module) connectors and make sure they seat correctly.
- Operate the system and determine if the concern is still present.
Is the concern still present?
Yes
INSTALL a new ACM (Audio Control Module). REFER to Audio Control Module (ACM) . TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR any DTCs present. TEST the system for normal operation.