TSB : Radio - AM Interference

Affected years: July 1999

Details

SI No. 367-2065 PI No. Date: July 1999 Distr. US 9-3 Radio interference on AM Cars concerned Saab 9-3 M99. Background The action package in this SI has been produced for use in connection with customer concerns(complaints about interference or poor radio reception when listening to AM stations. Always try to get the customer to describe the nature of the interference as precisely as possible, e.g. extraneous noise, tones, crackling, frying, motorboating, etc. and the circumstances in which the interference occurs. Materials 4B 72 685 Interference suppression kit for Trionic containing: Interference suppression capacitor Crimp pin Procedure Only the system or Systems which the following trouble-shooting procedures show are the cause of interference are to be rectified. If the car's antenna is in poor condition, the radio will be less resistant to interference and radio reception in general will be substandard. Therefore, start fault diagnosis by inspecting the antenna. A. Antenna's ground connection unsatisfactory. It is extremely important for the antennal to be properly grounded. This can be checked as described below. 1 Bend aside the luggage compartment trim behind the left-hand wheel housing. 2 Disconnect the antenna cable . 3 Undo the two nuts securing the antenna. 4 Place a piece of insulating paper between the antenna bracket and the car body. 5 Take a resistance reading across the antenna connector's screened plug and grounding point G3 below the left-hand rear light cluster. 6 If the reading obtained is less than 10 ohms the ground connection is OK. Remove the paper and continue with point B. 7 If the reading is above 10 ohms, adjust the lock washer until it Is in good contact with the body metal. 8 If the resistance reading obtained is less than 10 ohms after adjusting the washer, remove the paper and continue with point B. 9 If it is greater than 10 ohms there may be an open circuit in the antenna. Change the antenna/aerial and continue with point C. B. Free play in the antenna rod Free play/poor contact between the various sections of the antenna rod may occur. Check this as described below: 1 Switch on the radio and let the antenna extend to its fullest height. 2 Take a resistance reading across the top of the antenna rod and the centre pin of the antenna/aerial connector. 3 If the reading obtained is more than 30 ohms the antenna/aerial rod should be changed. 4 Connect the antenna cable . 5 Tighten the nut at the base of the antenna (unless this has already been done) and the two nuts securing the antenna/aerial. 6 Refit the luggage compartment trim. 7 If the antenna rod is dirty it can be wiped clean with a cloth (do not lubricate it with wax or oil). 8 Continue as described in point C. C. Background tone A background tone can be caused by the Trionic motor management system. To check Check whether the tone comes from the PWM control of the idle air control valve, as follows: 1 Start the engine and switch on the radio. 2 Unplug the connector from the idle air control valve in the engine bay. The tone should now disappear. Procedure The fault can be rectified by fitting interference suppression kit 48 72 685 (CA=30567466) as described below: 1 Remove the Trionic control module as described in group 2 "Trionic". 2 Unplug the connector and extract the socket at position 49 (red/blue lead). 3 Cut off the connector. 4 Cut all but 200 mm off the interference suppression capacitor's lead. 5 Twist the red/blue lead together with the interference suppression capacitor's lead in a new connector. 6 Refit the socket in position 49 of the connector. 7 Plug in the connector. 8 Mount the capacitor on the left-hand screw at grounding point G34. 9 Check the result of the above measures by starting the car and switching on the radio. Warranty Information A. Inspect/change antenna Failed part: 36741 Reason: 68 Type of coverage: 01/06 Check Change Location 0 0 Type of repair 08 01 Labor operation straight time 0.2 36741-0.2 B. Check/change antenna rod Failed part: 36743 Reason: 68 Type of coverage: 01/06 Check Change Location 0 0 Type of repair 08 01 Labor operation straight time 0.2 36743 -0.2 C. Trionic Checking/fitting interference suppression kit Failed part: 24810 Reason: 66 Type of coverage: 01/06 Check Fitting Location 0 0 Type of repair 08 10 Labor operation straight time 0.2 24810-0.2 + straight time 0.2 Disclaimer