Pinpoint Test A: Poor Reception - AM/FM
Information and Entertainment System
Pinpoint Tests
Pinpoint Test A: Poor Reception - AM/FM
Normal Operation
The AM/FM radio antenna receives AM and FM radio waves. The antenna then sends the radio waves to the Audio Control Module (ACM) through the AM/FM antenna cable.
The noise suppression equipment reduces engine ignition and electrical systems interference transmitted through the speakers.
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 only stops at songs falling within the selected category. If no song in the selected category is found, the ACM 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 self-test. This DTC applies to vehicles with navigation only.
- DTC B2103 (Antenna Not Connected) - sets when the signal strength is less than the pre-configured threshold value during the ACM self-test. In order for this DTC to set, the ACM must be tuned to AM, and the self-test must be run with the scan tool. This DTC applies to vehicles without navigation only.
This pinpoint test is intended to diagnose the following:
- No song found in the selected category
- AM/FM antenna
- AM/FM antenna cable
- Charging system
- Ignition system
- Noise suppression equipment
- ACM
PINPOINT TEST A: POOR RECEPTION - AM/FM
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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 song being found in the selected category.
No
GO to A2.
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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 A7.
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A3 CHECK THE NOISE SUPPRESSION EQUIPMENT
- Check all required noise suppression equipment and the radio frequency interference suppression bond for security, cleanliness, and metal-to-metal contact.
- Are the connections clean, secure, and in metal-to-metal contact?
Yes
GO to A4.
No
CLEAN and SECURE the antenna connections, or INSTALL new noise suppression equipment as needed. TEST the system for normal operation.
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A4 CHECK THE RADIO INTERFERENCE CAPACITOR
- Install a new radio interference capacitor.
- Start the vehicle.
- Operate the audio system in radio tuner (AM/FM) mode.
- Is the reception OK?
Yes
The cause of the concern was an inoperative radio interference capacitor. The system is now operating correctly.
No
GO to A5.
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A5 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 A6.
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A6 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.
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A7 CHECK THE AM/FM ANTENNA CABLE
- Ignition OFF.
- Disconnect: AM/FM Antenna Cable-to-AM/FM Antenna Connection.
- Disconnect: AM/FM Antenna Cable At ACM.
- Measure the resistance of the AM/FM antenna cable between the ACM and the rear AM/FM antenna cable; and between the front AM/FM antenna cable core and shield.
- Is the resistance of the AM/FM antenna cable core less than 2 ohms, and the resistance between the core and shield of the AM/FM antenna cable greater than 10,000 ohms?
Yes
GO to A8.
No
INSTALL a new AM/FM antenna cable. REFER to Antenna Lead-In Cable Antenna Lead-In Cable. TEST the system for normal operation.
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A8 ISOLATE THE AM/FM ANTENNA
- Connect: AM/FM Antenna Cable At ACM.
- Install a new AM/FM antenna. Refer to Antenna - AM/FM Antenna - AM/FM.
- 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.
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A9 ISOLATE THE AM/FM ANTENNA CABLE
- Ignition OFF.
- Install a new AM/FM antenna cable. Refer to Antenna Lead-In Cable Antenna Lead-In Cable.
- Operate the audio system in radio tuner (AM/FM) mode.
- Is the reception OK?
Yes
The cause of the concern was an inoperative antenna cable. The system is now operating correctly.
No
GO to A10.
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A10 CHECK FOR CORRECT ACM OPERATION
- Disconnect all the ACM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the ACM 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. REFER to Audio Control Module (ACM) 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.
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