Radio - Interference Noise

91jaguar05

86-92


Radio Interference Noise Due

To Fuel lnjector Pulse

MODEL 1991 MY Sedans DATE 6/91


ISSUE:

"Ticking" interference noise on the AM radio band.


ACTION:

Diagnose the possibility that AM radio interference is related to fuel injector pulse noise by using the following procedure:


NOTE: Interference caused by fuel injector pulse changes with engine speed and load.


^ Tune the radio to the AM station where the interference is strongest.

^ Drive the vehicle at approximately 35 mph. (Engine speed must be above 1500 rpm).

^ Depress the throttle heavily and determine if the interference noise increases. Release the throttle and determine if the noise stops during deceleration fuel cut-off, until fueling reinstatement occurs at 1100 rpm.

If the interference noise does NOT respond to changes in throttle, the problem is NOT fuel injector pulse related. Refer to Technical Bulletins 86-50 and 86-82.

If the interference noise does respond directly with engine speed and load, re-route the gearbox harness as follows:

^ Remove the ski-slope, radio, and climate control/clock panel.

^ Remove the right side A/C support bracket.

^ Disconnect the following gear-box connectors:

- GB-1 15 Way Brown PMHD
- GB-2 12 Way Black Multi-Lock
- GB-3 6 Way White Simitomo
- LB-35 14 Way Yellow Multi-Lock
- GBG-1 Ground Eyelet





^ Move the gearbox harness from the center of the transmission tunnel to the right side, tucking the harness between the right-hand A/C duct and the tunnel, (Fig. 1).


^ Remove the passengers side underdash panel.

^ Gently pull the harness away from the radio chassis area. Make sure that no gearbox harness wires remain below the radio.

^ Re-connect all connectors except for GB-3 (Sport transmission mode switch).

^ Route GB-3 along the right side of the J-Gate.


^ Install the A/C support bracket. The gearbox harness MUST be routed to the right of the bracket.

^ Install the climate control/clock panel, radio and ski-slope.

WARRANTY INFORMATION:

Fault Code: 7QAV
Repair Operation Number: To be claimed as shop time. Use standard "Shop Time" claim procedure starting entry with 86.50.


Time Allowance: 0.50 hrs.


SERVICE ADVISOR NOTE:

If the interference noise still exists after this procedure has been performed, no further action is possible at the present time. Service information will be issued when available.