Audio System - Whining/Buzzing Noise From Speakers
09-001/031991-2002 Navajo, B-Series, Tribute - WHINING BUZZING NOISE FROM RADIO SPEAKERS
Note:
This bulletin supersedes the following TSB(s): 09-015/01. Please update your records accordingly.
BULLETIN NOTE:
This bulletin supersedes 09-015/01, issued 12/21/01. The APPLICABLE MODEL(S)/VINs and PART(S) INFORMATION have been changed.
APPLICABLE MODEL(S)/VINs
All 1991-94 Navajo
All 1994-02 B-Series (excludes all Flexible Fuel (FFV) B-3000).
2001-2002 Tribute
DESCRIPTION
A whining or buzzing noise can be heard coming from the audio system speakers. This may be caused by an electrical noise coming from the in-tank fuel pump or its ground wire. A Radio Frequency Filter (RFI) is available to correct this concern. Customers having this concern should have their vehicle repaired using the following procedure.
NOTE:
^ Do not perform the following procedure on FFV B-3000 vehicles, this procedure does not apply. To verify if vehicle is FFV, check 8th digit of VIN.
^ If 8th digit is V then vehicle is FFV.
^ If 8th digit is U then vehicle is not FFV.
^ Fuel pump audio noise is relatively constant and changes only slightly with engine RPMs. If the audio noise constantly changes with the engine RPMs, the fuel pump is not the cause of the problem and the RFI filter will not effectively reduce the noise.
Customers having this concern should have their vehicle repaired using the following procedure.
REPAIR PROCEDURE
1. Verify customer concern.
a. Turn the key to the "ACCESSORY" position and turn ON the audio unit, tune the radio to a station with clear reception.
b. Turn the ignition to the "RUN" position (do not start the engine).
c. The fuel pump should run for about 1 second with the key in the "RUN" position with the engine not running. Listen for electrical noise in the speakers of the audio system.
^ If noise is present while the pump is running and stops when the pump stops, then the fuel pump is generating the noise. Proceed to STEP 2.
^ If noise is not present when the pump is running, or is constant even when the fuel pump quits running, then the noise source may not be the fuel pump. Refer to PINPOINT TEST 2: NOISY RECEPTION of the applicable Workshop Manual for additional troubleshooting and repair procedures.
2. Remove the fuel pump sending unit from the fuel tank. Refer to Workshop Manual (section F or 01) for removal procedure.
3. Remove the black (negative) and red (positive) connectors from the fuel pump.
4. Cut the black and red wires to the fuel pump 3 inches (76 mm) below the flange of the fuel pump.
5. Solder both the red and black wires of the RFI Filter to the red and black wires below the flange. Use heat shrink tubing over the solder connectors.
NOTE:
Heat shrink tubing must be used over all solder connections; covering the entire soldered area to prevent exposure.
WARNING:
All soldering and heat shrinking steps should be performed AWAY from the fuel tank area.
6. Connect the RFI filter connectors to the spade terminals on the fuel pump.
NOTE:
If RFI connectors do not fit to spade connectors on fuel pump; cut the connectors from the RFI filter and cut the fuel pump wires 1" (25 mm) above the pump wire connectors. Solder both the red and black wires from the RFI Filter to the red and black fuel pump wires.
7. Secure the RFI filter to the fuel pump assembly with a plastic tie-wrap to prevent rattling.
8. Install fuel pump assembly into fuel tank. Refer to Section 01-14 for installation procedures.
NOTE:
Do not reuse the fuel pump gasket, replace with a new gasket prior to reassembly.
9. Verify that the noise is reduced by using the testing procedure in (STEP 1).
^ If noise has been reduced, return vehicle to the customer.
^ If noise has not been reduced, proceed to (STEP 10).
10. Locate fuel pump ground wire (black) in the wiring harness on the left frame rail.
11. Locate one (1) unused 12 mm hole in the left side frame rail between the fuel pump and the fuel filter.
12. Clean and remove some of the finish in this area to ensure a good metal-to-metal electrical connection.
13. Cut the fuel pump ground wire to prevent it from acting as an antenna.
^ 1991-94 Navajo and 1994 B-Series-) Cut the fuel pump ground as close to the 12 mm frame rail hole as possible.
^ 1995 -) 97 B-Series-) Cut the fuel pump ground wire just before the X1007 connector. Seal the back of the X1007 connector with silicone sealant to prevent water from entering.
^ 1998-99 B-Series -) Cut the fuel pump ground wire just before the X-304 connector. Seal the back of the X304 connector with silicone sealant to prevent water from entering.
14. Attach an eyelet connector to the fuel pump side of the ground wire and secure the wire to the frame rail with a bolt, nut and washer, at the 12 mm hole.
15. Cover the ground with rust-proofing paint to prevent corrosion.
NOTE:
Corrosion protection is important since this wire is the operating ground for the fuel pump.
16. Verify repair.
PART(S) INFORMATION
WARRANTY INFORMATION
NOTE:
This information applies to verified customer complaints on vehicles covered under normal warranty. Refer to the SRT microfiche for warranty term information.
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