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TSB 08-30-96

Radio Interference to/from two-way radio receivers.

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Date: Sep 6, 1996

Models:   1995-1997 BR Ram Truck

Symptoms: Customers may complain of intermittent poor reception on their two-way radios and/or the windshield wipers may operate intermittently during two-way radio communication (wipers OFF).

NOTE: THIS CONDITION DOES NOT AFFECT THE OPERATION OF ANY AM OR FM BAND RADIO.

Discussion : Radio receivers from aprox 20 MHz to 174 MHz may be susceptible to RFI from the fuel pump module's motor and/or the HVAC blower motor. In addition, the windshield wiper delay module may be affected by radios operating within the 20 MHz to 174 MHz band..

The following services are within this band:

Diagnosis :
Turn ignition key to the run position (HVAC controls must be OFF and wipers OFF). Operate the two-way radio and monitor for RFI/static/poor reception. Turn the HVAC controls ON and operate the blower fan through the different speeds while monitoring for RFI/static/poor reception. Start the engine and monitor for RFI. Next, key the transmitter and monitor for intermittent wiper operation.

If there is RFI with the ignition key in the run position (HVAC controls OFF, wipers OFF, and engine OFF), RFI is being emitted from something other than the fuel pump module's motor or the HVAC blower motor. If RFI is identified while the HVAC blower fan is running, perform repair procedure A.
If RFI is identified while the engine is running, perform repair procedure B.
If the wiper motor intermittently operated during any radio operation, perform repair procedure C.

NOTE: IT IS IMPORTANT TO IDENTIFY WHICH COMPONENTS ARE EMITTING RFI. AFTER A REPAIR HAS BEEN COMPLETED, PERFORM THE DIAGNOSIS AGAIN TO IDENTIFY ADDITIONAL SOURCES. SOME VEHICLES MAY REQUIRE ALL THREE REPAIR PROCEDURES.

Parts:

1     04883825AA   filter, RFI ,  for fuel pump module
1     04883826AA   filter, RFI ,  for HVAC blower fan motor
1     04883827AA   filter, RFI ,  for windshield wiper motor delay module

Repair:

Repair Procedure A   This repair involves installing an RFI filter in series with the blower fan circuit.

  1. Record the radio station presets.
  2. Disconnect and isolate the battery negative cable.
  3. Remove the glove box door by disconnecting the lanyard on the left side of the door, depressing the stop tab at the rear of the bin and then pulling the door away from the instrument panel.
  4. Locate the orange, two-wire connector which is visible through the opening in the rear of the glove box cavity. Disconnect the connector.
  5. Mate the connectors on the filter with those on the fan motor. Check both pairs of connectors to make sure that they are properly mated.
  6. Apply foam tape around the RFI filter and upper connector end.
  7. Install the glove box door panel. Remove the kick panel in front of the passenger side door.
  8. Locate the wiring harness ground termination on the sheet metal behind the kick panel.
  9. Remove the ground termination bolt. Install one eyelet of the new ground wire (wire located in kit) on the termination bolt and secure the bolt.
  10. Remove one of the bolts that secures the blower motor housing to the HVAC housing. Install the other end of the ground wire to the bolt and reattach the bolt.
  11. Install the kick panel.
  12. Connect the negative cable and reset the clock and reprogram the radio to the station presets.
Repair Procedure B  This repair involves installing an RFI filter in series with the electric fuel pump motor.
  1. Record the radio station presets.
  2. Disconnect and isolate the battery negative cable.
  3. Disconnect the fuel pump module connector at the fuel pump module. The connector has a locking tab that must be released prior to disconnecting. Depress the lock tab and slide the connector apart.
  4. Connect the RFI module to the harness and to the fuel pump module connector. Secure the connectors by sliding the red lock tab back into its original position.
  5. Apply foam tape to the back of the RFI module.
  6. Secure the RFI module by tie strapping it to the truss bracket. The truss bracket is adjacent to the fuel tank rail and chassis rail.
  7. Connect the negative cable and reset the clock and reprogram the radio to the station presets.
Repair Procedure B  This repair clamps three RFI filters to the intermittent wiper module's wiring.
  1. Record the radio station presets.
  2. Disconnect and isolate the battery negative cable.
  3. Remove the 5 screws that secure the knee bolster to dash panel and remove knee bolster.
  4. Locate the intermittent wiper module located under the instrument panel and above the accelerator pedal. Slide the module off its mounting bracket.
  5. Separate the nine wires entering the connector on the back of the module into three groups. Install a snap-together filter on each of the three groups of wires. The filter should be placed as close to the module as possible.
  6. Apply foam tape around the RFI filters.
  7. Install the knee bolster.
  8. Connect the negative cable and reset the clock and reprogram the radio to the station presets.
notes:
RFI filter available at no charge under the TSB if you have that problem.  It will be installed for you at no charge as well as CC pays for the TSB service.

 

Thanks to Bob Bergevin for supplying this TSB information

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This page was edited on: May 3, 2004