Antenna - Power Cadillac Brougham I

DESCRIPTION

The General Motors automatic power antenna is activated whenever radio and ignition are turned on or off. Major components of the General Motors power antenna are: antenna assembly, lead-in cable, switches, motor and gear housing, gear and spool assembly, mast and tubing, and a power antenna drive unit. The drive unit is encased in a 2-piece plastic housing with mast and tube assembly attached. (Scheme 1)

OPERATION

With ignition switch in "ACCESSORY" or "RUN" position and radio turned on, voltage is applied to antenna relay coil. The relay contacts close and battery voltage is supplied through Dark Green wire to antenna motor, driving antenna mast up. The other motor terminal is grounded through the internal antenna motor up switch (Gray wire and relay contacts). At the end of upward mast travel, up switch opens and motor stops.

When radio or ignition is turned off, the circuit through antenna relay coil is opened and contacts move to a position which applies battery voltage to White wire. The Dark Green wire is now grounded, reversing the motors polarity. The motor now runs in reverse and drives antenna mast down.

Once antenna mast is fully down, internal antenna motor down switch opens and breaks current flow. Both sets of switches are now open.

Scheme 1

ANTENNA DOES NOT RAISE OR LOWER

Check for blown fuse, loose electrical connections on receiver or antenna, bent mast or defective relay. See TESTING in this article.

Should mast meet with an obstruction while cycling to full extension, it automatically recycles in 30 seconds and attempts to reach full extension. If obstruction remains, cycling will continue every 30 seconds. If mast is obstructed during downward cycle, mast stops where obstruction occurred. No recycling takes place as in the up cycle.

FADING OR WEAK RECEPTION

Probable cause is moisture in support tube from condensation or leakage. Remove antenna and disassemble. Clean drive housing or replace as required.

EXCESS IGNITION NOISE, ERRATIC AUDIO OR REDUCED CB RECEPTION

Check for poor grounding of antenna at mounting or at lead-in system. See GROUND CHECK in this article.

PRELIMINARY CHECK

1. Unplug antenna lead at back of radio and plug in a known good antenna. Ground the test antenna and keep hands off mast. Check reception in an area away from electrical interference.
2. Tune radio to high and low ends of dial in both AM and FM bands. If reception is okay, a problem exists with antenna and/or lead-in cable. If reception is still poor, radio may be at fault.

LEAD-IN CABLE CHECK

Broken center conductor of lead-in cable will normally result in no AM and weak FM reception. In cases of continuous reception problems, check lead-in with an ohmmeter. (Scheme 2) When checking resistance, wiggle lead-in tip and cable. If results are not as listed in chart, lead-in should be replaced. See LEAD-IN CABLE RESISTANCE table.

Scheme 2

LEAD-IN CABLE RESISTANCE

GROUND CHECK

1. Lower antenna mast. Remove escutcheon from fender. Attach alligator clip to upper end of mast to act as antenna. Leave other end of clip unattached.
2. Tune radio to a weak AM station or a station which is received when clip is attached and not received when clip is removed. Remove clip. Ground upper end of mast to fender with very short jumper wire.
3. If station is not received, antenna grounds are good. If station is still present, or even stronger, a poor ground or no ground condition exists.
4. Possible ground loss points are: antenna upper mounting (screw loose, paint overspray), coaxial connector at mast not connected or corroded, coaxial connector at radio not tight or corroded or quick connector corroded.

ANTENNA OPERATES BUT DOES NOT COMPLETELY RAISE OR LOWER

1. If motor operates, pull up on top section of mast. If mast moves freely, plastic drive cable is broken. Replace mast and support tube. If cable is not broken, remove mast and support tube. Check mast sections for binding.
2. If binding exists, eliminate binding or replace mast and support tube. If no binds exist, check drive cable for broken hook. If no breaks exist, replace gear and spool assembly. Refer to, in this article, «MAST & CABLE, GEAR & SPOOL ASSEMBLY»(/cadillac/brougham/i-1987-1992/remont/antenna-systems/#antenna-power) .

ANTENNA DOES NOT LOWER

1. If the motor does not operate, check CLK-CIG fuse in fuse block. If fuse is blown, remove relay and install new fuse. If fuse blows again, repair short in Orange wire. If fuse does not blow, check for short in White wire. If there is no short, replace relay. If White wire is shorted, repair wire. If there is no short, repair motor.
2. If the fuse was good in original check, use test light and check for 12 volts on Orange wire at antenna relay. If light does not glow, repair open in Orange wire. If light glows, check for voltage at White wire on relay.
3. If light does not glow, replace antenna relay. If light glows, check for open in White wire. If no open exists, check for voltage at Dark Green wire. If light glows, check relay connections and ground wire. If both are okay, replace relay. If light does not glow, check for loose connection between relay and connector or connector to antenna. If okay, repair motor.

ANTENNA DOES NOT RAISE

1. If motor does not operate, check fuses in fuse block. If radio fuse is blown, repair radio. If CLK-CIG fuse is blown, remove antenna relay, install new fuse and recheck. If CLK-CIG fuse is okay, disconnect 3-wire connector with White wire and install connector with Orange wire at antenna relay.
2. Recheck fuse. If blown, replace relay. If okay, check for short in Gray and Dark Green wires from relay to antenna motor connector and to the antenna assembly. If no short, replace antenna motor. If new fuse blows, repair short in Orange wire from fuse panel to connector.
3. If fuses were okay in original check, turn ignition off. Connect test light to Orange wire at relay connector. If light does not glow, repair open in Orange wire. If light glows, turn ignition and radio on and listen for relay click.
4. If relay does not click, check for open relay ground, open in Pink wire, or bad radio switch. Probe Pink wire with test light. If voltage exists, replace relay. If relay clicked, check for voltage at Dark Green wire in relay connector. If light does not glow, replace relay.
5. If light glows, check for voltage at Gray wire. If light glows, check relay connections and ground wire. If okay, replace relay. If light does not glow at Gray wire, check for open or short in Gray and Dark Green wires. If okay, repair motor.

Note. The following procedure is a general procedure for all vehicles. Not all steps apply to all models.

Removal

1. Disconnect negative battery cable. Remove fender inner splash shield. Remove instrument panel sound absorber.
2. Disconnect antenna lead-in connector from radio and antenna relay. Remove antenna-to-fender attaching retainers. Remove tire and wheel if necessary to gain access under fender. Remove inner fender supports.
3. Remove antenna bracket bolts, or lower antenna attaching screws. On Cadillac RWD models, attach a 4-foot guide wire to top of antenna to help guide mast sections out of housing. On all other models, with all wiring disconnected, gently guide wires and antenna through fender opening.

Installation

To install, reverse removal procedure. On Cadillac RWD, use guide wire to guide new antenna into housing.

1. Remove power antenna unit from vehicle. Remove 4 cover-to-housing eyelets. Remove 5 retaining clips. Using a small screwdriver, carefully wedge cover from housing. Clean excess and/or loose sealer from cover and housing.
2. Separate mast and tube assembly from gear housing and unwind cable from gear spool as required to gain access to attaching hook. Unhook end of cable from gear. If replacing gear and spool assembly, slide gear and spool assembly from housing post.

Note. Switch, armature or field assembly need not be removed to remove gear and spool assembly.

1. Extend replacement mast as required until approximately 10" (250 mm) of cable are left exposed. Hook end of cable in gear and route cable in spool. (Scheme 3) Position mast and tube assembly on housing so rubber drain pipe fits into housing hole and mounting ears are located in housing slots.
2. Push excess drive cable into tube assembly as required to keep cable in gear spool. Position cover on gear and motor housing. Install nuts and bolts which attach mast and tube assembly to housing. Install remaining bolts and nuts and 5 retainer clips.

Scheme 3

WIRING DIAGRAMS

For wiring diagrams, refer to appropriate chassis wiring diagram in WIRING DIAGRAMS section.

See also:
• TESTING