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Old 01-21-2008, 12:14 AM   #1
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Default Interesting Problem with Power Antenna

Wife brings the 94 home in evening with casual mention that antenna did not retract on shutdown. Not a big deal... its old, its cold, maybe it froze up.

Next morning battery is deader than dead. I suspected the antenna, so unplugged the antenna relay in the trunk, and installed a battery from another car. Without starting the car, I then turned the radio on and off several times, to try to get a reading on voltages at the relay. At one point I plugged everything back together just to see if there had been any change, or if a fuse would blow, but the antenna still would not retract, so I unplugged the relay again right away.

The car was not started on the replaced battery until later.... but when it was, the alternator is toast. Possibly a coincidence, but I wonder?!?. Could the diodes have toasted at the time of the original problem or during my momentary reconnection of the relay?

Replaced the alternator as well as the battery, and everything fine. Have not reconnected the relay, of course.

I put 12 volts directly to the DOWN terminals of the antenna motor, and I can hear a hum, like a stalled electrical motor, but nothing useful happens. The schematic shows that with the radio off (or car shutdown) "hot at all times" is applied to the DOWN side until the internal switch is broken when the antenna actually GOES down. So it was sitting with power to the antenna motor all night. Interesting that the fuse would not blow.

Next step is to remove it. Haven't checked out how easy (or how expensive) to find another one, but I will probably try to get a peek inside the case first, in case it is something simple and fixable.
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Old 01-21-2008, 10:33 AM   #2
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The fuse won't blow because there'* no load. The plastic coil has broken loose inside, so the motor is turning in a no-load condition. It'll run until you're dead.



If the alternator was weak to begin with, the added stress of trying to charge a dead battery could kill it. Usually, if a better is over 4 or 5 years old and it gets replaced, it'* best to have your alternator tested at the same time. A weak battery can stress an alternator, and a weak alternator can kill a battery.



You need a 10mm ratchet or wrench to remove the antenna. Undo those two 10mm bolts in the trunk, disconnect the relay and antenna connections as well as the case drain to the fender, and pull the antenna assembly DOWN into the trunk. Reverse the procedure with an antenna from the wrecker for 20 bucks. Get one from a 97-99 if you can find one, simply because they're newer.

Drill out the rivets on the new one, clean the gear housing out, and re-grease with either magnalube or white lithium grease, then use machine screws and nuts to reassemble. The antenna should outlast you now.
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Old 01-21-2008, 11:04 AM   #3
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We are seeing more and more battery drain problems due to faults in the power antenna.
Glad you found it. Some will retract and still drain the battery somehow if the limit switch goes.
Thats my next project when at the yard, to look for a 97-99 unit as i just unplugged mine in the SSE in the up position.
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Old 01-21-2008, 11:27 AM   #4
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I got 99'* for both of my cars at different times. The Zilla is happy still after 4 years, and the SLE is over 2 years on it'* replacement now.
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Old 01-23-2008, 10:37 PM   #5
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Default Antenna Problems solved

Quote:
Originally Posted by SSEBONNE4EVA
We are seeing more and more battery drain problems due to faults in the power antenna.
Glad you found it. Some will retract and still drain the battery somehow if the limit switch goes.
I got my power antenna solved.

It has a rather bizarre mechanical arrangement for the limit switches, which requires that the motor and motor-shaft (and worm gear) be allowed to travel longitudinally....for a quarter inch or so, each way from its normal working position.

When the antenna reaches the end of travel and jams the motor, the worm gear still has to pull itself along for that quarter inch, dragging an arm to activate the limit switch. You can hear a click as it activates. If it fails to activate, power is applied to the jammed motor forever, which is the battery drain you are seeing.

Similar thing going the other way... a second arm, a second limit switch.

Three problems....
1. motor shaft frozen to the lower bushing.
2. gunk with old grease fills up the shaft channel and the motor can't easily travel longitudinally, so those arms don't move....... and/or
3. the limit switches have bent enough so that the arms no longer activate one or both.

The quality of the limit-switch contacts still looked okay after 13 years.

Cleaned out all the gunk and re-greased.... bent the limit switches a little more so that the arms will activate them earlier, and first tests look good.

It is a pretty tenuous arrangement for protecting against unwanted power drain... considering that it is "HOT-AT-ALL-TIMES" to the motor, whether the radio is shutdown or operating.

There IS an internal circuit breaker. Usually, in electric motors, thats exactly for preventing power when the motor is stalled, but obviously it does not do its job in this assembly. While testing, I had power to that motor while stalled a whole lot of the time, and the "circuit breaker" never blinked once....

..
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