How do you replace the mast on a 1992 Lexus sc 400 antenna?
i have nover heard of being able to replace the mast, most the ones that i have worked on you will have to replace the comlete motor and assembly with mast.
The above answer is incorrect as the question pertains to the Lexus SC 300 / 400. My answer is probably true for most Lexus vehicles (it has been my experience that they utilize nearly the same engineering for most common pieces.) Although I've never heard of being able to "nover" anything.
First make sure you only need the mast assembly. If when turning on or off the radio you hear the antenna motor turning its gears in attempt to raise or lower the antenna, then you are good to go. If not, you will need to replace the complete motor housing (which should always come with a new antenna mast assembly.)
Next Google 'Your Vehicle' Replacement Antenna Mast, where 'Your Vehicle' is the year and model of your vehicle. So, 92 SC400 Replacement Antenna Mast in the case above. Of course, the mast assembly is interchangeable for all SC300/400 models from 1992 to 2000. You will notice around the web they sell for about 50 bucks, but if you check eBay you can typically find them for 15 to 20 dollars shipped. At this point if your motor was broken you should search for, Complete Antenna Replacement Unit. They can be had on eBay, used but with a brand new mast, for 60 to 100 dollars shipped.
If all you need to do is replace the mast, utilizing a flathead screw driver and a mallet (preferably rubber), tap the round locking nut on the top of your rear, drivers side quarter panel to loosen it, thus allowing it to be removed. Pull the antenna and mast out of the motor housing. Make sure that it is the same length as the replacement mast, if it's not then you've got some broken pieces inside the motor. If that's the case you're going to need to clear out the trunk panels in order to gain access to the motor. Remove the motor from it's mounting brackets and fish out the remaining plastic piece or pieces.
Once you have either replaced the motor or removed the mast, simply slide the lock washer and locking nut over the mast and insert the mast into the hole left in the quarter panel. Ensure that the business end of the mast is inserted into the motor housing and push down on the mast seating it as deep into the motor as it will go. Loosely screw down the locking nut, just in case you need to trouble shoot the next step.
Turn on the radio. The motor should lower, then raise in an attempt to grab the new antenna. If it fails to do so, make sure that the mast was properly inserted into the motor. Nine times out of ten if something goes wrong at this point it's because the plastic end isn't properly seated into the motor housing. After the motor is able to raise and lower the antenna, secure the locking nut. If all went well the antenna will be successfully installed leaving nothing to do but enjoy the silent radio waves as they stream music into your audio system through your newly installed power antenna!