FINAL CHAPTER...My Cobra still runs when the ignition switch is turned off...

willow1308 · #1 (**permalink**) 09-06-2011, 07:44 PM

CHAPTER 1....Last month I started a thread about my BDR continuing to running after the ignition was turned off...(not run-on...but full engine operation)...

It was suggested I should replace the ignition with a brand new Painless ignition switch...

CHAPTER 2...I purchased the new switch...and installed it...drove the Cobra several miles (during daylight without the lights on)...started and shut down the engine several times...seemed to solve the problem...

To test my new ignition switch again...I took the Cobra for a short spin the next night with the lights on...pulled back in the garage...turned off the key... the engine continued to run...I didn't try turning the lights off...but instead got out and disconnected the ignition...

At this point...it was suggested by forum members I install a 1A-100 V Diode...

FINAL CHAPTER...I drove the Cobra tonight...I have not had a chance to install the 1A-100V Diode....but turning off the ignition key turned off the engine...I tested this several times...each time the Cobra shut off...as dusk approached...I turned on the lights and drove back to my garage...as a further test to isolate the problem.. I left on the lights and turned off the ignition switch...Cobra still ran...this time I turned off the lights...the Cobra shut down...

So it appears my problem only occurs at night with the lights on...so if I shut off the ignition switch...but do not turn the lights off first...the Cobra still runs...

I'm going to install the Diode when I get a chance...but with my new info...any further thoughts on my problem...

Thanks,

Randy
BDR #340

PDUB · #2 (**permalink**) 09-06-2011, 10:34 PM

In digital logic that is called a wired OR... ignition OR lights make the car run. Somehow the lights are providing power to the ignition separately from the ignition switch.

That means if you turn on the lights, push the car and dump the clutch she'll go

...

Are you using a relay for the lights? If so, that might be where the issue is. Check the wiring there...

undy · #3 (**permalink**) 09-07-2011, 03:24 AM

The lights are back-feeding the ignition circuit through the alternater lead. Install the diode. That should do the trick

willow1308 · #4 (**permalink**) 09-07-2011, 07:28 AM

Quote:

Originally Posted by undy

The lights are back-feeding the ignition circuit through the alternater lead. Install the diode. That should do the trick

Thanks...that's also my best guess...

Rick Parker · #5 (**permalink**) 09-07-2011, 07:46 AM

Electricity at one extreme not only has the ability to KILL you, but also has the ability to give you gray hair. Install the diode and get some rest.......it takes very little energy from a switched 12 volt source to trigger the ignition box remember it is hard wired with 10 gauge wire for actual operating current. This phenomenon was one of the very first tech issues that had to be resolved when aftermarket ignition systems first hit the market.

SkipB · #6 (**permalink**) 09-08-2011, 08:28 AM

Just don't go out at night! Simple solution. Requires no electrical work or parts. Ha!

willow1308 · #7 (**permalink**) 10-23-2011, 04:57 PM

UPDATE...the newer Backdraft's have the headlight circuit wired thru the ignition switch instead of being powered thru the battery kill switch...

I updated my wiring to the new specs (now wired thru the ignition switch)...

Additionally...I never have to worry about my lights remaining on after I turn off the ignition switch!

Problem solved 100%...

Thanks to the forum member that made me aware of this solution!

Randy
BDR #340

tcrist · #8 (**permalink**) 10-23-2011, 05:31 PM

Anybody have pictures/part number of this diode and how to install in when using a one wire alternator.

I have the same issue sometimes. Only when it is warmed up. Never when it is cold. I.E. if I start it up, pull it into the driveway it will shut right of with no problem. After it is warmed up, sometimes it will not shut off.

If I hold the brake on and use the clutch to kill it, no problem cranking it back up even after a month as setting there will not run the battery down. So it must be feed back from a power source.

TIA