Pinpoint Test A: Poor Reception - AM/FM
Information and Entertainment System
Pinpoint Tests
Pinpoint Test A: Poor Reception - AM/FM
Refer to Wiring Diagram Set 130, Audio System/Navigation for schematic and connector information. Diagrams By Number
Normal Operation
The AM/FM antenna receives AM and FM radio waves. The antenna cable transfers the radio waves to the Audio Control Module (ACM).
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 channels falling within the selected category. If no channel 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 channel found in the selected category
- Antenna
- Antenna cable
- Charging system concern
- Ignition system concern
- Noise suppression equipment
- ACM
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.
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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 channel 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 (Gas), C1104a (Diesel - Primary), Or C1251a (Diesel - Secondary).
- Start the engine.
- Operate the audio system in radio tuner (AM/FM) mode.
- Is the reception OK?
Yes
INSTALL a new generator for the suspect 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 (Gas), C1104a (Diesel - Primary), Or C1251a (Diesel - Secondary).
- 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 ANTENNA COAXIAL CABLE
- Ignition OFF.
- Disconnect: Antenna Coaxial Cable (At Antenna).
- Disconnect: Antenna Coaxial Cable (At ACM).
- Measure the resistance of the antenna coaxial cable core between the antenna and the ACM.
- Is the resistance less than 2 ohms?
Yes
GO to A8.
No
INSTALL a new antenna cable. REFER to Antenna Cable - AM/FM Antenna Cable - AM/FM. CLEAR any DTCs present. TEST the system for normal operation.
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A8 ISOLATE THE AM/FM ANTENNA
- Connect: Antenna Coaxial 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 antenna. The system is now operating correctly. CLEAR any DTCs present.
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 Cable - AM/FM Antenna Cable - 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 antenna cable. The system is now operating correctly. CLEAR any DTCs present. TEST the system for normal operation.
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. CLEAR the DTCs. REPEAT the self-test.
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