Radio - Noise
Bulletin No. T 86-21File in Group 9
Number 29
Corp. Ref. No. 806 8872
Date Dec. '85
SUBJECT: RADIO NOISE (ALTERNATOR INDUCED WHINE)
MODELS AFFECTED: 1985, 1986 DE VILLE, FLEETWOOD, AND CIMARRON (EXCEPT VEHICLES EQUIPPED WITH DELCO-BOSE)
Some late 1985 and early 1986 De Villes, Fleetwoods and Cimarrons built between April, 1985 and shortly after the start of the 1986 production may exhibit a radio noise, primarily in the left channel speakers, which is induced by the alternator. Cars built with the optional Delco-Bose premium sound system are not affected. The condition is evident even with low alternator electrical loads, and the level of noise does not change when the radio volume is changed. The audio circuits in these radios may be susceptible to picking up the noise if a marginal radio ground circuit exists. After the start of production 1986 the radio circuitry was changed to eliminate this susceptibility.
Cars exhibiting this type of radio noise can be repaired by revising the radio ground circuit as follows:
1. Cut or remove the black ground lead from the black connector at the rear of the radio.
2. Install a ring terminal on to the previously removed ground wire and reconnect ground wire to the radio case using an existing radio case screw.
IMPORTANT: A parallel ground to the radio case will not correct the condition. The ground wire in the black connector must be disconnected from the radio ground terminal.
For warranty purposes use labor operation T-6136 for .3 hours to complete the above repair.