V70 XC AWD L5-2.4L Turbo VIN 56 B5254T (1998)
Technical Service Bulletin # 3390025
Radio - Interference/Noise On AM Band
This service bulletin replaces the previous service bulletin SB 390025 from February 2001, which should be discarded.
Additional source of electrical interference, V70 rear seat ground, is added.
AM Radio diagnostics, interference
This Service Bulletin explains how to fault trace sources electrical interference with the AM radio. Electrical interference can influence the quality of
radio output, and can sometimes be confused with poor AM reception because the result is similar. Static is heard in the speakers.
Before deciding to fault trace for AM interference, refer to Service Bulletin 39-0018: AM Radio Reception Diagnosing. It the number of received
stations compares to a similar car, the cause of static may be electrical interference. After determining that the antenna system and station reception are
not the primary cause, follow the diagnostic information in this Service Bulletin.
Electrical interference causes static noise by inducing a signal that is picked up by the vehicle wiring and transported through the antenna input to the
AUM. Electrical interference is usually noticed as static on the AM band, and is most noticeable between stations. To determine the source of electrical
interference, the best method is to selectively isolate or activate switches and nodes, one at a time, until the static is reproduced or eliminated. Static
caused by electrical interference is usually rhythmic and reproducible.