Pinpoint Test E: Poor Reception - AM/FM
Information and Entertainment System
Pinpoint Tests
Pinpoint Test E: Poor Reception - AM/FM
Normal Operation
The radio antenna receives AM and FM radio waves and sends them to the Audio Control Module (ACM) through the AM/FM antenna cable. The ACM powers the AM/FM antenna in order to amplify the AM signal.
The noise suppression equipment reduces engine ignition and electrical systems interference transmitted through the speakers.
For vehicles equipped with premium sound, 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 B2103 (Antenna Not Connected) - sets during the antenna connected test (part of the ACM self-test) when the signal strength is less than the pre-configured threshold value. In order for this DTC to set, the audio system must be tuned to AM, and the self-test must be run with the scan tool.
This pinpoint test is intended to diagnose the following:
- No channel found in the selected category
- Antenna
- Antenna cable
- Charging system
- Ignition system
- Noise suppression equipment
- ACM
PINPOINT TEST E: 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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E1 CHECK THE RDS SETTING
NOTE: If the vehicle is equipped with base sound, proceed to step E2.
- 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 E2.
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E2 CHECK THE AUDIO SYSTEM RECEPTION
- Operate the audio system in radio tuner (AM/FM) mode.
- Check the reception with the engine running, and with the engine off.
- Does the poor reception only occur with the engine running?
Yes
GO to E3.
No
GO to E7.
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E3 CHECK THE NOISE SUPPRESSION EQUIPMENT
- Check all required noise suppression equipment (including the ACM ground strap) 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 E4.
No
CLEAN and SECURE the connections, or INSTALL new noise suppression equipment as needed. TEST the system for normal operation.
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E4 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 E5.
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E5 CHECK THE GENERATOR
- Ignition OFF.
- Disconnect the wiring harness from the generator voltage regulator.
- Start the engine.
- Operate the audio system in radio tuner (AM/FM) mode.
- Is the reception OK?
Yes
INSTALL a new generator. REFER to Charging System Service and Repair. TEST the system for normal operation.
No
GO to E6.
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E6 CHECK THE IGNITION CIRCUITS
- Ignition OFF.
- Connect the wiring harness to the voltage regulator.
- 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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E7 CHECK THE AM/FM ANTENNA ENABLE CIRCUIT
- Ignition OFF.
- Disconnect: Antenna C400.
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the voltage between the antenna C400-2, circuit VME43 (BK), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to E9.
No
GO to E8.
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E8 CHECK THE AM/FM ANTENNA ENABLE CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Disconnect: ACM C240a.
- Measure the resistance between the ACM C240a-5, circuit VME43 (BK), harness side and the antenna C400-2, circuit VME43 (BK); and between the ACM C240a-5, circuit VME43 (BK), harness side and ground.
- Is the resistance less than 5 ohms between the ACM and the antenna, and greater than 10,000 ohms between the ACM and ground?
Yes
GO to E12.
No
REPAIR the circuit. TEST the system for normal operation.
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E9 CHECK THE AM/FM ANTENNA CABLE
- Ignition OFF.
- Disconnect: AM/FM Antenna Cable At Antenna.
- Disconnect: AM/FM Antenna In-Line Connection At RH Kick Panel.
- Disconnect: AM/FM Antenna Cable At ACM.
- Measure the resistance of the rear AM/FM antenna cable core between the antenna and the front AM/FM antenna cable in-line connection; and between the rear AM/FM antenna cable core and shield.
- Measure the resistance of the front AM/FM antenna cable core between the ACM and the rear AM/FM antenna cable in-line connection; and between the front 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 E10.
No
INSTALL a new front or rear AM/FM antenna cable. REFER to Antenna Cable - AM/FM Antenna Cable - AM/FM. TEST the system for normal operation.
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E10 ISOLATE THE AM/FM ANTENNA
- Connect: AM/FM Antenna In-Line Connection At RH Kick Panel.
- Connect: AM/FM Antenna Cable At ACM.
- Install a new AM/FM antenna. Refer to Antenna Service and Repair.
- Operate the audio system in radio tuner (AM/FM) mode.
- Is the reception OK?
Yes
The concern was caused by an inoperative AM/FM antenna. The system is now operating correctly.
No
GO to E11.
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E11 ISOLATE THE AM/FM ANTENNA CABLE
- Ignition OFF.
- Substitute each AM/FM antenna cable by routing a new component. Do not remove the original antenna cable at this time.
- Operate the audio system in radio tuner (AM/FM) mode.
- Is the reception OK?
Yes
INSTALL a new AM/FM antenna cable for the inoperative cable. REFER to Antenna Cable - AM/FM Antenna Cable - AM/FM. TEST the system for normal operation.
No
GO to E12.
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E12 CHECK FOR CORRECT ACM OPERATION
- Disconnect all the ACM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the ACM connectors and make sure they seat correctly.
- Operate the system and verify 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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