Audio - Static on Weak AM Stations
88cadillac10
Bulletin No. T-89-9 File in Group 9
Number 51
Corp. Ref. No. 9003R
Date Sept. 1988
SUBJECT: AM RADIO STATIC ON WEAK STATIONS
MODELS AFFECTED: 1986-1988 BROUGHAMS
This information supersedes Serviceman Bulletin T-87-116, Group 9 (Corporate Reference Number 719003) which should be destroyed.
Some 1986-1988 Broughams may exhibit a condition of AM radio static on weak stations. This condition may be caused by voltage induced from the distributor to the harness for the power antenna. This condition may be repaired using the following procedure:
FIGURE 1 - POWER ANTENNA CONNECTION AND GROUNDS:
Rerouting the power antenna harness:
1. Disconnect connectors and grounds, items 4 through 11 in Figure 1.
FIGURE 2 - REROUTE HARNESS:
2. Reroute harness as shown in Figure 2.
FIGURE 1 - POWER ANTENNA CONNECTION AND GROUNDS:
3. Reconnect connectors and grounds, items 4 through 11 in Figure 1.
FIGURE 2 - REROUTE HARNESS:
4. Use a tie strap, P/N 11509088, to retain harness to brace assembly, Figure 2.
If the static has not been fully removed after following the above procedure, install capacitors on the power antenna circuits. To install the capacitors, follow the procedure below:
Parts Required PN Quantity
Capacitor 1227894 3
Eyelet 2977489 1
1. With the ignition "off", disconnect the negative battery cable.
2. Disconnect the power antenna connector.
3. Backout the terminal for circuit 145, the dark green wire in cavity A, from the antenna side of the connector.
FIGURE 3 - INSTALLING CAPACITORS:
4. Position one lead of capacitor P/N 1227894 (.47 ufd, 200V) to the backside of the terminal crimp. Solder the capacitor lead to the terminal, refer to Figure 3A.
5. Tape capacitor lead to the circuit wire. Be sure to securely wrap tape around capacitor leads so that they are completely insulated, refer to Figure 3B.
6. Reinstall terminal into connector.
7. Repeat steps 3-6 for circuit 161, the gray wire in cavity B.
8. Repeat steps 3-6 for circuit 160, the white wire in cavity C.
9. Gather the three remaining untaped, unsoldered capacitor leads together.
10. Solder 4 ft. length of 18 AWG (.8 metric) wire to the junction of the three capacitor leads.
11. Securely wrap tape around the capacitor leads so that they are completely insulated (including soldered portion of the 4 ft. wire).
12. Solder other end of 4 ft. wire to an eyelet, P/N 2977489 or equivalent, refer to Figure 3C.
13. Attach the eyelet to the braided ground strap at the cowl.
14. Reconnect the power antenna connector and the negative battery cable.
All parts are currently available from GMSPO.
For warranty purposes use Labor Operation T6205 at .4 hour to reroute power antenna harness. Add .3 hour if capacitors must be installed to correct condition.