Batboard

Hi everyone; after 35 + years of installs, I finally got one that totally baffles me. (Maybe I'm gettin too old for this? LOL)

1997 Volvo 850, straightforward install. UHF Syntor X9000, 452.750 Mc.
EVERYTHING checks out perfect, a textbook install. BUT

When radio is off hook (CSQ) I hear a 250ms noise burst EVERY TEN seconds, whether the car is on, off or ruuning.

Burst does not get through PL.

Is definitely coming from car, since my truck sitting in the yard doesn't hear it. Portable in car does not hear it.

I am assuming its coming in on the A+ line.

The people at Volvo, though really nice, had no clue, and they admitted they were just guessing when they said it might have something to to do with self diagnostics. the "alarm" cycles at around every 5 seconds or so, and does not correlate with the burst.

I am probably missing something VERY obvious here, so you guys please help me out... because its NOT a customers car...

IT'S MY WIFES !!!!

thanks, keep smiling and of course: 73!

Mike in CT
KM1R

I searched all over the internet and I can't find any other similar complaints. Thats interesting that it does it with the car off, usually annoying noises only occur when the car is on (and your trying to hear something really important....).

It's got to be one of Volvo's fancy dancy computer things. Those cars are like space ships. Does the power go right to the battery or to something else? Does it still do it with the antenna unplugged?

Check out everything related to scan.

If the car has a clock with analog hands, check it!

Most mechanical automotive clocks work by a windup solenoid that plunges the spring every 10-30 seconds and is famous for making noises.

Try pulling fuses one-by-one until the problem goes away. Once you find the one that eliminates the sound, you at least know of which circuit branch and which devices can cause it.

I would look deeply into the alarm system and power door lock circuit, also.

Check the fuel pump. Many of the ford vehicle fuel pumps run and "prime" themselves intermitantly when the car is off. Might be something similar even 10 second bursts.

Ever come up with a solution to this?

Just an observation, but maybe the radio has a problem. You say you have the problem if the car is on or off. While you probably have it wired to ignition, can you bench check the radio??

He pm'd me a while ago about it - pretty much had it narrowed down to the fuel pump.