CDI does not want to turn off continously buzzing, humming
 

Hi fellow pelican members,

My CDI does not want to turn off even if the ignition & engine has been shut off. the CDi continously hums /buzz. The only way to turn it off is to detach the negative cable of the Battery. When the negatve cable is reattached to the negative pole of the battery the CDI does not buzz/hum. Only when the ignition is switched on and the engine is started. When I shut down the engine there continous buzzing /humming of the CDI.
The car is an 89 911 turbo coupe USA car.


Thanks in advice guys,


tdh888

There is a timer on the CDI that allows it to run for a few seconds after the key is turned off. It sounds like that relay is sticking. There is a thread in the archives about the run-on relay and how to bypass or replace it. Jim Fairman posted a picture I believe.

Here is one:
http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/535961-delayed-ignition-cut-off-relay.html?highlight=delay+relay+CDI

Here is the one I was thinking of:
http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/682123-cdi-help-please-before-i-sell-damn-car.html?highlight=delay+relay+CDI

.

Had the same problem a couple of years ago, it was the Delayed ign cut off relay.

Thanks guys for the reply , i will ask my tech to check out the the delayed ignition cut off relay.

930

Hi ,

Is this right part no. Of the ignition cut off relay 930 617 112 02 that I need for my car. If its not can someone please help me find the proper part no.

Thanks a lot guys,

tdh 888

Hi guys,

Thanks to all of you who replied. It was indeed the Ignition Cut Off Relay w/c was the culprit. Brought the CDI & the Ignition Cut Off relay to my electronic tech whose expertise is repairing High End tube & solid state Hi Fi equipment.He checked them both .No problem w/ the CDI. The Ignition Cut Off Relay's diode was the culprit. He replaced both transistor (since its available) and diode w/ the same brand as the original parts . My mechanic installed it this morning and it works perfectly. It cost me less than $30 for parts & labor.

tdh888