If it will go halfway up, that means your antenna mast is extremely dirty.
Have someone turn on the radio while you assis the antenna to go up higher.
Once you get it as high as you can, clean the antenna with wd40 or
similar... exercise your antenna up and down... cleaning each time it goes
As Tiger said, it's probably that your mast is sticky. It's a pretty
straight-forward job to replace the mast itself, I got one from
AutohausAZ for $15. Once you get it out, you take the cover off of the
unit to see how the mechanism works, and you can force it to spit the
old antenna out and then suck a new one in. For what it's worth, you
don't need to take the mechanism out of the case (as I did, 'cause I
didn't know how to get the old antenna out), just turn the black plastic
gear a bit to kick off the motor (with the ignition switch and radio on
and switch in the "up" position) and the old antenna will pop right out.
Should be easy to figure out. On my list of TODOs is to videotape the
process and stick it up on YouTube, since I have to pull mine out again
since I didn't get it adjusted quite right.
I don't know about your car but my 84 500SEL has a switch on the dash that
makes that happen. You can make it stay down, go up part way, or go up all
I have no idea how it works but the problem could be in that system if your
car has it.
Very likely it's the antenna mast. You can tell for sure just by
listening. If the motor keeps running but the mast stops going up
before being fully extended, then it's a mast problem, not
electricial. Cleaning and lightly lubricating it may solve it, at
lleast temporarily. You can get it fully extended as your cleaning it
by pulling on it while the motor is running to assist it.
But what happnes over time is the plastic cable that is used to push
it out, gradually wears out. And I think it probably rapidly wears
out once it's stuck and failing to extend, because that section of
cable is then getting even more wear. So don't be surprised if it
starts sticking again soon.
I don't hink you even need to remove the unit to install the new
one. It's supposed to be able to be done by just pulling it out by
hand as the motor is making it go up. You then feed the new one back
in as it's in retract mode. However, I think it's a good idea to open
the case, clean out any gunk, and put some oil on the roller/tension
pivot points. If that gets corroded a bit, it won't keep tight
tension holding the cable against the wheel that moves it.
The masts are available on Ebay for ~ $15
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