Jack71

Well, here is the series of events, symptoms facts. Any help is appreciated because I'm going to miss New England Lars Day if I can't get this fixed...

1) Turned off key one day and engine kept running. I had to pull the coil wire with an oven mitt on to stop it
2) Since I have an MSD box and run-on is a common problem, I thought the issue was related to the ballast they recommend. But with quick voltmeter test, I determined the fuse panel had 11.5V on the IGN and ACC circuits with the key out of the ignition.
3) I then suspected the ignition switch was faulty, so I completely disconnected all three connectors to the column. Still have juice on the IGN circuit.
4) I pulled the dash harness, or is the rear harness (located in front of the fuse panel) and still had juice on IGN.
5) Pulled the wires from the starter, still have Volts on the IGN circuit.
6) After scratching my head for a moment, I remembered "The damn Amp!!" so I pulled the hot wire to the amp and IGN finally had no juice.
7) Thinking "phew I found it"... I hooked the starter wires back up and pow... 11.5V on IGN circuit again. (Without amp hooked up)

Now I'm sure this next event means something, but my lil brain isn't working too good right now, so I'd like to borrow yours for a moment...

8) I was playing around and determined that any power at the starter or amp caused a hot IGN circuit. The HOT wire from amp accidently grounded to the seat frame and -- Badda Bing 11.5V on the IGN circuit.

Does this mean my system has an open ground somewhere??? Can some help me out please!!!!! I have 16 days before Lars Tuning Day and need to get this car to shut the F off.

jfb

Many circuits have 12v on them with the ignition off. Your engine should not run with the ignition off since the ECM will not pulse the injectors UNLESS you have somehow bypassed the ignition switch with your aftermarket whatevers installed! You need to take a look at how power was run to all of your add-ons!

71coupe

Did you have this problem before you installed your MSD? They have a fix for engine run-on conditions. There should have been a diode in the box if you bought the unit new, if not, you can get one at Radio Shack.
Click on this link for details
http://www.msdignition.com/1troub1.htm#runon

Jack71

This is a new problem -- I also have the diode installed.

My IGN is hot when the car is not running.

I know there's quick fix for this problem, I'm just trying to narrow the hunt. If I could figure out what circuit its leaking in on for example, that would be great.

How hard is to pull the bulkhead connector?

NHvette

Whoa. Stop tearing things apart for a minute.
Can't turn off is a bit more forgiving than can't start up.

I'll stare at the wiring diagrams today and try to figure out
the possibilities.

By the bulkhead connector, do you mean the connector on the
front of the fuse panel (engine side) ? This is easy to remove ...
just a bolt in the center of the connector and pull off.
But, this will disconnect any feed from the battery to the
interior. I'm not sure what it will tell. Perhaps it will narrow
the search to the engine compartment ... if ignition is still 'hot'.

I'll be out working on the vette all this weekend. If the rain holds off, you
are welcome to drive over, and I will help trace the problem.
The garage is not currently accessible.

Are you sure you didn't do anything recently that would cause electric problems ?

-Dave

Jack71

Hi Dave,

The run-on condition is a side effect of the ignition circuit always being hot (I figure). With the key out, the igntion should be dead. The only thing I changed out was my wiper motor. I pulled the connections to make sure it wasn't the culprit.

What do you think about #8?? That leads me to believe my ignition circuit is grounded at some point.

Disconnecting the bulkhead connection would help me determine if the fault is in engine compartment or interior (I think).

Jack71

Also, the wiring in this car was shakey to begin with before this problem. Thanks for the offer to help, I really hesitant to drive with this type of problem. If smoke appears on the road I'd have to pull the coil wire to stop the car!

I'll buy the beer if you're up for a spin down over the weekend. I'm in West Boxford by Haverhill.

wills670

is the 12 volt while cranking wire at the starter still hooked up?
it maybe a bad starter solinold sending 12 volts to coil or are you sure you have not hooked up that wire to the 12 volt (big terminal) instead of the (r) terminal on the solinold.

Jack71

That is a Gold Star guess, but I unhooked that wire with the MSD box and distributor.

NHvette

I REALLY REALLY can't afford to skip a beat, or I won't be driving either.
My body drop is tomorrow ... then I need to install my entire body wiring, too.
What sux most .. is ANOTHER weekend of rain showers. ARRGGGHHH

How is your coil connected ? Is it a ring terminal - like stock ?
I could make you up a switch today that you could put inline
with the coil power wire to disable (no cutting) - until you figure it out.
We can even make the wires long to reach into the passenger compartment.
I'm planning on being here in Burlington til 6:30ish tonight.
You can stop by anytime, but let me know.
Teratech Corp 77-79 Terrace Hall Rd, next to the Baron apartments.
Easiest way is to go to the end of B Street - our parking lot and shipping dock area.
Map : http://www.mapquest.com/maps/map.adp...te=ma&zipcode=

Jack71

Given the symptoms, I'm not going to drive this puppy until its fixed. Freaks me out driving with a serious electrical problem. I appreciate the offer though for the switch.

NHvette

OK - so let's try to figure it out here.
Regarding #8 - not sure. Is the "badda-bing" after you started having troubles ? I'm gonna start looking at the wiring diagrams.

If I get hung up due to rain, I might be able to make it out there Sunday.
If not, maybe some evening (next week) on the way home. I usually leave here
between 6 and 7.

EDIT: just re-read the original again. I was under the impression that AMP meant the ammeter guage. I now realize it is the audio ampliifer.

The AMP power wire must be connected directly to the positive battery cable (with a fuse - likely).
Is there a low power turn-on connection for the amp ... usually connected
to power antenna lead from radio or switched (ACC) circuit ?
If so, you might have a short inside the amp that is connecting BAT to ACC.
This still doesn't explan the ACC power when just the starter is connected.

You were definitely on the right track to disconnect the forward harness
from the fuse box.
Then we can narrow it down to 1/3 of the wiring.

Jack71

You don't miss a beat on the AMP, yes it does has a lead wire from the radio but disconnected that too.

I'll see if I can get the forward harness off, looks like an underneath job. Is there a screw underneath all that gunk holding that thing on?

I don't want to slow you down either. So I'm happy to come up one night and lend you another set of hands on your project.

NHvette

Yeah - if there is tar covering the center ... scrape it away carefully.
Right in the center of the outside connector (actually two halves)
there is a bolt. I forget the size, but it must be a 1/4 or 5/16 - so
7/16" or 1/2" socket. Loosen the bolt and pull the connector straight out.

You might NOT want to volunteer for helping me. I skipped last night, but
the night before I was in the garage 10PM-2:30AM. This weekend rain
is killing me. I have just about everything done - that I can do indoors.
I'll still stop by some night - if need be, but I'm not staying until 2:30 !!

NHvette

OK - another late night, but I was taking a break from torqueing
bolts and looked through the electrical section of my Haynes manual.

I think it might be your voltage regulator. If you have the stock
regulator, there looks like a relay inside that can connect BAT-IGN.
This might be stuck. You could try the regulator connector
before removing the forward harness

Jack71

Isn't the voltage regulator internal to alternator? I tried disconnecting the alt pigtail with no change. But I think one wire is switched hot and their a battery wire. I'll take a closer look at that harness today, thanks...

NHvette

If you haven't reomoved the front harness connector yet ...
It's a 3/8" wrench you need.

Jack71

I just pulled the engine harness, and the IGN circuit was still hot in the car. So now (duh) I'll just start pulling fuses out of the panel to isolate the problem. Any other ideas that I should try? This is killing me.

magicv8

When you pulled the bulkhead connector, you disconnected the fuse box from the front of the car. If the underhood ignition has 12volts now, begin disconnecting alternator, wiper motor, etcetera - if the 12volts drops to zero on the ignition line, you have found the culprit, but my guess is the harness is fried. The good news is you will be able to remove the harness easily after disconnecting everything.

There is a chance that some wires run to the compartment from the cabin, since this car has probably seen some wiring work in the last 34 years.

NHvette

When you say "in the car" - do you mean engine compartment,
passenger compartment, or both ?

I agree with magicv8 - and that's the direction you are headed anyway.

I could try to stop by Wednesday night ... tentatively ... if you haven't found it by then.