Help! 81 check eng stays on key off

[81capecod vet]

hecklight stays on key off checkd alt not prob new ign instl still stays on light stays on dains bat puts power to alt plug need help b4 i go bald my 81 vet the check eng light stays on when key off i checked altenator it is not the problem i put in new ignition switch it is not problem i have non computer carb

holly i have early 4 pin distributor non computer i took out ecm and the fuse the light goes out when its running but when key off kills bat and powers up alt 2 wire plug delco sockt

 

[bill81vette]

Would you please spell out you words...I Can't understand what your trying to ask.

 

[Wajulia]

You have NO ECM in the car and the check engine light is still on, that's interesting. You changed the ignition switch because of this -- that's interesting also. The quickest fix -- remove the light bulb!!!!

If you have a disconnected light that is lighting there is Only two possibilities 1) the disconnected wire has shorted to some other circuit 2) there is a ground problem in the dash and some strange sneak path to ground through the disconnected circuit.

Short:
What is the voltage at the light bulb. If it is 12V, there is most probably a short in the circuit board or the wire going to the Disconnected Connector at the ECM. Check the connector for the ECM, has it shorted or degraded or corroded? follow the wire and circuit board looking for the short.

Bad grounds:
they can cause all sorts of strange non-understandable things to happen. I am not sure how that circuit board is grounded, but follow the ground paths and assure they are all tight and clean.


Let us know what happened

 

[81capecod vet]

if i took out the bulb i still would have the drain it also powers up the alt 2wire plug at altenator i also whent ahead and changed solinoid on starter so so far no ecm no ecm fuse non computer control carb (holey) 4pin distrib (non computer) light still stays on when all wireing is disconnected at alt even battery fed all grounds check fine wireing seems fine adbu.rning my brain out cant figure it out does any one have anny other thoughts

 

[Wajulia]

if i took out the bulb i still would have the drain it also powers up the alt 2wire plug at altenator i also whent ahead and changed solinoid on starter so so far no ecm no ecm fuse non computer control carb (holey) 4pin distrib (non computer) light still stays on when all wireing is disconnected at alt even battery fed all grounds check fine wireing seems fine adbu.rning my brain out cant figure it out does any one have anny other thoughts

But the alternator is consuming no power, the light bulb is. You are simply reading the battery voltage at the alternator. Which when the key is off, is wrong! You changed the solenoid on the starter, the ignition switch, removed the ecm, changed the carb, but you wont remove a light bulb. I am at a loss. I would not expect anything to change when you remove the wires from the alternator when the key is off. The power is coming from the battery at that time, not the alternator!


My apologies, but I really recommend that you get a schematic, and most importantly, someone who understands basic electricity and automobile electrical systems, and debug the problems. Else, change the tires, that might help

 

[81capecod vet]

reply to wajulia's response thank's for your thoughts i thought this was a serious web sight for people to help each other not go to commedy night well ill guess ill keep looking for real people who work and build there on cars not buy and pay for others to do it by the way im totaly quilified i own licenced and regesterd auto body shop in ma i build & rebuild my own cars ground up if you would like ill buy you tires i hope you well thanks for your comments
good luck with your day job

 

[Wajulia]

I was serious when I gave you advise that you summarily dismissed. You are randomly changing parts based on no discernible logic. If you are going to continue to randomly change parts for a problem that is obviously a short or a bad ground -- go ahead. If you don't want to listen to advice, don't ask for it.

 

[Peer81]

Alright, I read this topic from the beginning to the end.
Simply said, Wajulia has a logical story to tackle this problem. Nothing strange about it. And I totally agree with him.

For the topic starter... Really, first buy yourself a good wiring harness schematic. Second first think about what you're trying to accomplish then see what is the best and most logical way to do this. Then if 12v stuff is not your best subject no problem always people that are willing to help. But if you think we are telling you a made up story and you're changing part like you never seen a car before. I would be scared dropping off a car at your shop!

So on topic, get the bulb out and get done with it, or tell us what the real problem is.

Greetings Peter

 

[81capecod vet]

found prob it was in jack storage compart relays roy coch from gm in dedham ma a retierd instructor at training center help me thanks all ps if i removed light bulb it still draind