Hello all,

I recently replaced the dash in my grey 300SD and after doing so, I have noticed that the antenna and radio are acting oddly. The only electrical-related change I made was swapping the antenna switch for one in slightly better cosmetic condition.

The symptoms started when reconnecting the radio. The display showed garbled digits and when I hit the "On" button, the radio made a click sound like a relay and nothing happened. I rotated the fuse and noticed my battery was very low. It seems that somehow I have an electrical drain all of the sudden; more than what I would expect from the clock. After charging the battery, I could get the radio to come on if I put the antenna switch in the "off" position. I could then extend the antenna. Now, if I extend the antenna all the way via the switch, the antenna gyrates up and down about 1/2" and the speakers make a popping sound with the antenna motion. The antenna and radio were in 100% working condition before the dash swap and switch replacement. I'm wondering if a faulty switch would cause this behavior or possibly a stuck relay? If there is a relay??? I'm pretty sure the electrical drain was related to the antenna or radio because I could extend and retract the antenna via the switch with the key off. I don't recall being able to do that before. Perhaps it is some feature that is enabled when the door is opened; like the electric seats. I can't remember if I had the door open or not. I can try it on my other 300SD and see what that tells me.

Any advice? I'm still scratching my head on this one. Once I get some time, I will try swapping the original antenna switch back in but I'm not sure that is the answer.

Thanks!

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

I also swapped another radio in and it made no change in the symptoms.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

The fader switch is connected but the window switches and mirror switch are not.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

looks can be deceiving?
don't judge a book by it's cover?
I'm guessing the radio switch is bad...

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

It sounds like a missing ground. Check the ground strap for the antenna housing and pin 6 of the antenna connector.

I know this has nothing to do with the dash work but whenever I see flaky problems like this, I usually check for ground problems.

It has been quite a while since I've dug into the console and dash wiring. Is the antenna switch connector one that is easy to attach in reverse?

The antenna switch is connected:
Pin 2 (bu) - - - radio (bk/wh)- - pin 5 antenna
Pin 3 (bu/gr) - - - - - - - - - - - -pin4 antenna
Pin 4 (bu/yl) - - - - - - - - - - - - pin1 antenna
F16 - - - - - - - - - - - - - - - - - pin 2 antenna

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

As soon as I get a combination of daylight and time, the switch is the first thing I will replace. It only seems logical since it was the only part that changed. My grounds should be good and clean since I serviced them a while before the dash came out. Nothing related has been an issue beforehand.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

Ground would be a possibility but I replaced the antenna with the same model, but working, less than a year ago. I also made sure the ground was secure. None the less, it is worth a second look.

I believe the antenna switch is keyed, so it will only attach one way to the wire harness.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

I replaced the antenna switch with the one that was originally in the car and the problems have gone away.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge