MGW-Fla

Yeah, there is something in the link of the power to rear defrost switch circuit that can cause it to still feed power & cause the run on syndrome. I know there is info here on RL regarding it. I just learned on any sharks owned since, "Nooooo usey the rear defrosty!"

Mrmerlin

while your looking at the CE panel,
I would suggest to make sure that the owner didnt fill every fuse slot,
also look at the relays as possibly there are slots filled that shouldnt be,
or the relay may be in the wrong position,
or a 53 relay may be installed in the wrong slot, BTDT

Ninjaxz750

So I decided to head over to West Chester Cars and Coffee with the boy this morning so he could see the cars there. I pulled the car out and warmed it up, turning on the rear defroster. After going thought traffic from hell (thank you for Saturday Construction) we finally get there. I turn the key and pull it out of the ignition and the car is wondrously continuing to run. I **** my head sideways like a puppy, put the key back in, turn in on and then off; still running. the accessories turn off when I pull the key, but it still runs.

Nice eh?

I give up, lock the doors, enjoyed the show and grab Starbucks for the both of us. When everyone cleared out we left, and headed home. As I drove home, I notice the Rear Defroster was lit. Then I realized the switch was stuck pushed in. I pulled it back out, and when I got home the car shut off easy peasy lemon squeezy. BUT, the Rear Defroster stayed lit. I restarted and then shut off the car and the Rear Defroster light went out.

Why does this happen? Is this a switch and/or a relay issue? Shouldn't there be an easier way to cut off the circuit without restarting and stopping it? The manual does not mention the ways to shut it off (other than waiting 15 min). There's an Off position, but that not the end all be all of this little issue.

I got home, did some searching here and found this thread. Had to share

Lizard928

It's the rear defrost switch every time.

danglerb

Not suggesting I know what is going on, but ...

If you have a poor ground connection that is shared any of those shared circuits that has power will feed backwards the other circuits. Anything in those shared circuits that has a good ground connection may have enough power to operate, especially if we are talking a very low current device like a relay coil.

Ninjaxz750

check connections and make sure grounds are up to par: Got it.

That was something I was thinking about. Thanks.

Bertrand Daoust

I think you have two problems here.

1) Bad switch as it was stuck pushed in. Maybe it just needs to be clean.
2) Bad relay as the timer in it doesn't work anymore. Very common problem.

https://rennlist.com/forums/928-foru...-turn-off.html

Hope this will help.

Ninjaxz750

Thanks. Apparently I didn't search far back enough.

Bertrand Daoust

No problem.

Also, I'm quite sure I read something here about this switch problem and the car not turning off.
But can't remember where and when...

Mrmerlin

FWIW when you have this issue happen.

To shut off the the engine simply pull the fuel pump fuse.

Then turn off the key.

Make sure the defroster switch is turned off and pulled out.
then start the engine this should shut off the defroster relay,

otherwise it may stay stuck on.
Replace the fuel pump fuse.

sstrickstein

Deoxit time

Mark R.

Wow. You walked away and went on with your day, while your car was still running..?!?



I am truly impressed. There is absolutely no way I would have been able to do that.

My mind would have been so preoccupied with that dilemma, to even think of anything else.

LOL I guess I just need to learn how to relax...

I wonder what others thought when they came upon your unattended running car...

Ninjaxz750

I might have acted like Joe Cool, but believe me, my mind was racing at 200 MPH. I did lock the doors since the key was liberated from the ignition at that point in time.

I also didn't want to ruin it for the youngster. I did think about heading back home to do some troubleshooting, but I also didn't want to get hammered with a 100 questions from my wife.

So I chose cool cars!

17prospective buyer

Bad on any car really since you now have a constantly fluctuating voltage, like it a fuel system/fluids, a battery of considerable size acts as a damper/accumulator for voltage spikes, it smoothes voltage spikes due to loads. CPU's need consistent average voltage to work properly.

dr bob

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