One more Automatic Antenna question
 

Just got a replacement Hirschmann power antenna from a junkies and it worked fine in that car (goes all they way up and down). Put it in my 1988 420SEL and it goes halfway up and stops. Does go all the way down though. Do I have to reset it for the new car or something? The car it came from was a 1987 300SDL. If I pull out the whole mast then put it back in (like a repair/replacement) will this get it to go all the way up and down correctly? :(

On my '86 560 SEL the power antenna goes up to about 1/3 of its length when you first turn on the radio. To raise it to full length you must use the antenna switch on the dash. When the ignition or radio is turned off the antenna goes all the way down.

That is what my 190E does as well. Read online and in the owners manual that this is by design. TO go up only like 12-16 inches and then needing the button pushed to go the rest of the way. I just keep my button locked in the Up position and it only rises when the radio is selected. If I select CD, Mini Disk, or Sirius it goes down.

You said that the antenna works fine in another car. If your dash switch is in the MAX up position, and your antenna still does not rise all the way, then most likely your dash switch is at fault.

Do this....disconnect the plug from the top of the antenna. Make sure dash switch is in MAX up position. Put the ignition on to turn on the radio...make sure the radio is now on. Now, check pin 1, 5, and 4 for power. You can use a meter or probe. I use one of those cheap probes with the built in light and nice alligator clip for the ground. Mine lit up nice and bright.

If any of these do not light up, you have narrowed down your problem.

Do a search over on Car Audio. Lots of in depth discussion on this. Saint's advice is good. I'd also be suspicious of the circuit board inside the donor unit's compatability with the wiring in your '88. If you can, verify that the junker's set-up, including the dash switch, is identical.
IMO, that dash switch is useless for 99% of the radio reception scenarios that anyone in north america would encounter. Any which way you can to modify the wiring to get the Hirschmann to go all up and all down with the radio is the way to go.

This isn't really relevant to the original question, but it's FYI for other readers.

I bought a newer, slightly smaller Hirschmann from a guy on eBay. It needed a little wiring adapting, but it doesn't have the "halfway up" function. It goes all the way up with the rocker switch in either the middle or up position. I don't miss it at all.