Radio - Interference On AM Band
90volvo10MODEL GROUP NUMBER
700 39 706
TITLE
RADIO INTERFERENCE ON AM-BAND
700 --> 1990 INCLUSIVE
MARKET DATE
US and Canada December 1990
REFERENCE: TP 31208/1 (ENGLISH); 11/88; RADIO
AM-band radio interference
Transient interference may be experienced on the AM band when items such as the brake light switch, main light switch, electric window winder switches and rear window heater switch are operated. Interference from the ignition system may also occur.
A service kit, p/n 3533250-1, has been introduced to suppress the interference. The kit consists of four ferrite rings and a ground lead.
Note: Both the ground lead and rings must be installed to achieve maximum suppression. However, the lead is not required on the 1988-90 760 (which already comes equipped with the ground lead installed).
Some cars may be fitted with a supplementary wiring kit connected to the rear of the radio chassis. This must be removed since it will interfere with the suppression properties of the ferrite rings.
Remove radio
Remove radio control knobs (four).
Undo catches and remove radio.
Remove glove compartment.
Remove supplementary wiring kit
On some cars, the radio may be fitted with a 9-pole supplementary wiring kit and a condenser screwed to the radio chassis as illustrated.
Unscrew condenser and remove wiring kit. Reconnect ordinary radio wiring.
INSTALLATION OF RADIO GROUND LEAD
Applies to: 740 - 1990 *
760 1982-1987
Note: This step does not apply to 1988-90
760s.
* Later 740s may already be equipped with the new ground lead also.
If not already installed, attach angled terminal lug supplied with kit to rear of radio.
Push ground lead onto lug.
Run lead to bottom bracket on right-hand side panel.
Fold back carpet on right-hand side and secure lead to body using bracket screw.
Reinstall radio and glove compartment.
Reinstall carpet.
INSTALLATION OF FERRITE RINGS
4-door 1982-1990 models
Open trunk, fold back carpet, and remove plastic cover over radio aerial.
Undo aerial connector.
Thread ferrite rings onto aerial lead.
Wrap rings tightly together with foam plastic supplied and secure with ties at each end.
Ensure that screen of aerial lead is grounded to body. Use ohmmeter to measure resistance between screen and body.
Note: Measure resistance between screen and body as illustrated, not between screen and fuel pipe.
Resistance should be 0 ohm. If higher reading is obtained, remove aerial at body mounting point, scrape off paint around underside of hole and apply rust inhibitor.
Reinstall aerial (tighten to 4 N-m) and check that resistance is now 0 ohm.
Reconnect aerial lead. Secure ferrite ring "package" to lead using third tie supplied with kit, using appropriate method as follows:
- If car is equipped with electric aerial, secure rings to aerial tube
- If car is equipped with ordinary aerial, secure rings to adjacent wiring harness.
In either case, ensure that "package" cannot rattle.
Reinstall plastic cover and carpet.
5-door 1982-1990 models
Remove rear interior light and rear roof liner panel.
Loosen top of D-post panel, lift and remove.
Undo aerial lead connector.
Thread ferrite rings onto aerial lead.
Wrap ferrite rings tightly together with foam plastic supplied with kit and secure with ties at each end.
Ensure that screen of aerial lead is grounded to body. Use ohmmeter to measure resistance between screen and body. Resistance should be 0 ohm. If higher reading is obtained, remove aerial at body mounting point, scrape off paint around underside of hole and apply rust inhibitor.
Reconnect aerial lead. Secure ferrite ring "package" to lead using third tie supplied with kit, using appropriate method as follows:
- If car is equipped with electric aerial, secure "package" to drain hose and cable sleeve using third tie supplied with kit.
- If car is equipped with ordinary aerial, thread third tie through holes in D-post and secure "package" as illustrated.
In either case, ensure that "package" cannot rattle.
Reinstall D-post panel, roof liner panel and interior light.
During the New Car Warranty period, claims must be submitted under:
Oper. No. Labor Description Time Allowance
Radio, r & i; ground lead, install 0.2 hr.
395 234 Ferrite rings, install - 4-door 0.2 hr.
Ferrite rings, install - 5-door 0.3 hr.