engine wont switch off

could you provide the diagram you used?
are you using points or a module?

here is the link to the wiring diagrams. i have used all three, fans, headlight and ignition. Wired exactly as per diagrams.

I am using a pertronix electronic distributor, no points and pertronix coil. wiring is just two wires from distributor to +ve and -ve on coil.

http://pantera.infopop.cc/eve/...221043316#7221043316

Horace; If you pulled the ground post, and the engine is continuing to run, then you have a grounding problem in which the electrical system is still being grounded.
With a VOM perform an open circuit test to check for an open circuit.
The Pantera ground is rather complicated in that the ground wires are looped from one device to another and all end up at a grounding stud located up under the dash on the driver's side.
Another place to look is the charging indicator light on the back of the speedometer where you should have a 15 ohm resistor in parallel with the charge indicator light.

when you switch OFF, can you tell if this relay de energizes

does the CHARGE lamp in the speedometer glow?

when you switch off and the engine is still running, depress the brakes and put it in reverse to turn on those lights.

It could be the alternator charging circuit is back feeding enough to keep the coil energized, but the original path to the coil would pull backfeed down and stop the engine

Thanks guys, in answer.

I have been pulling off the +ve side of the battery and it still runs so don't think its a ground problem. Apart from wiring up the new load shedding relays nearly all the wiring is stock and yes the earths are under the dash.

I am using a powermaster single wire alternator so the regulator has been removed.

Yes the relay is de energising and yes I have the 15 ohms resistor on the back of the speedo.

The gen light comes on as normal on ignition and goes out as normal on engine start

I think it is normal for the battery being able to be completely removed with the spinning alternator and the car remain running.

if you have a one wire altenator, I wonder how the gen light is working.

If your new ignition relay is dropping out when switched off, really need to see how your dizzy and control module is wired (or supposed to be) to determine where electrical is coming from

Sorry they call them "one wire alternators" but apart from the heavy charge wire from the amp gauge there is a small terminal on the side for the gen light wire.

The power to the +ve on the coil I have taken from 87 on the relay as per the diagram, this is then looped to the distributor as per the Pertronix instructions.

I am thinking it maybe the new relay. If I turn the ignition off surely it should just cut the power. I am going to try a temporary bypass around this new relay and see what happens.

I sort of understand the alterntor wiring (but I'll put that aside for now)

If wired properly, I would think that either the relay contacts are being held closed when the coil is deengized OR the coil is being held energized from something on other than the key RUN switch.

a trouble shooting matrix I would use to record VDC

For a quick test remove the small wire from the alternator and try starting and stopping the engine. If it works properly with that light wire disconnected then you need a diode installed in that wire.

the recomended wiring to make the GEN lamp
http://www.powermastermotorsports.com/075_IS_150.pdf

as for the diode to prevent reverse current, couldn't it be put in the jumper at the regulator connector?

If the ignition continues to fire after the key is shut off, one possible cause may be voltage is continuing to be supplied to the coil and/or ignition module. However, a second possible cause is the carburetor butterflies being too far open at idle, as a result of "retarded" ignition timing at idle (6 degrees).

If both the fan & ignition circuits are modified as I've drawn the ignition and fans will not interact with one another. But, problems arise with the Pre-L cars when folks try to use existing wiring. My hope is always that folks will "strip" the wiring far enough back that problems inherent in the wiring harness are eliminated. Other modifications such as non-original alternators can impact this, as well as other wiring changes made by previous owners.

The little blue alternator idiot light does not need to be functional. The car is equipped with either an alt gage, or the alt gage has been replaced with a volt gage. Either of those gages provide more information than the little blue idiot light. Its not needed, unless you have an original style mechanical voltage regulator I would hope the blue light has been left inoperative.

Here's my check list.

(1) Time the engine as suggested (18 degrees static, vacuum advance attached to ported vacuum), or use the idle solenoid the car was originally equipped with, so the butterflies are reasonably "closed" when the key is turned off. Otherwise the engine will want to "diesel" ... i.e. continue running.

(2) An ignition power relay should isolate the ignition (coil and module) from any source of power when the key is switched off. If it doesn't ... why not? This is easy to check.

(3) The modified fan wiring I've suggested will positively isolate the fans from the car's entire wiring system when the key is turned off. They will not be capable of "back-feeding" power to anything.

Hi George

Can you confirm that the wire out of 87 on the relay actually goes to the the +ve on the coil. Not sure exactly of the wording "new ignition" if it does I have wired it all correctly as per the diagram.

quote:

Originally posted by Horace Cope:...I have to pull the coil lead to stop it....

would that be
the HV plug wire to the dizzy
OR
the +ve wire to the coil

quote:

The little blue alternator idiot light does not need to be functional.

Yes, and no.

The filament in that bulb serves to complete the charging circuit. If that bulb burns out, then the ceramic resistor attached to that bulb's holder serves to complete the circuit.

One or the other pathway needs to be in place.

Larry

The problem is that the alternator is supplying enough voltage via the warning light to keep the relay's contacts closed.

This is due to the warning light AND the ignition (relay coil) both being connected to the RUN terminal of the ignition switch.

With the Bosch/Tyco type relays, once the relay coil is energized, it will remain energized until the voltage drops below 2 volts (usually around 1.2 volts).

As Joe (JFB) suggested, adding a diode in series with the charge indicator light's wire should solve the problem. The diode's "banded" end points towards the alternator.

John

I had the same problem with my car when I installed the new GM alternator. I found that stepping on the brake drew enough voltage that the engine would shut off. But, John Buckman correctly diagnosed my issue (below).

quote:

The problem is that the alternator is supplying enough voltage via the warning light to keep the relay's contacts closed.

This is due to the warning light AND the ignition (relay coil) both being connected to the RUN terminal of the ignition switch.

With the Bosch/Tyco type relays, once the relay coil is energized, it will remain energized until the voltage drops below 2 volts (usually around 1.2 volts).

As Joe (JFB) suggested, adding a diode in series with the charge indicator light's wire should solve the problem. The diode's "banded" end points towards the alternator.

Here's the specific info John sent me that solved my problem. The diode (Radio Shack P/N 276-1143) is installed in SERIES with the wire for the warning light (alternator's #1 terminal), with the diode's "band" toward the alternator (i.e. the wire that you attach to the banded end of the diode goes to the alternator, and the non-banded end goes to the warning light).

As an FYI when selecting a diode, you want the voltage to be at least 3 times the operating voltage of the system, and the current rating (amps) of the diode should be at least 1.5 times the current that the diode will normally see when installed.

Did you get this resolved?

No not yet, I ordered the recommended diode online and still waiting for it, hopefully it will arrive today. I will post an update here once I get it sorted.

Been away at the Le Mans Classic and only just back, superb event.

Although you have not tried the fans yet the fans should also have a diode on their grounds.
Try disconnecting the fans power.

I agree with Chris. I've also seen the fans turn into generators and run the engine. I even "think" I remember this being covered in one of the TSBs.

ok... so just flipped through the TSB book...and don't see one for the fan run on... Man, I thought there was one in there...

Thanks guys

The diode fitted inline between the alternator and generator lamp (B/BK) did the trick.

Engine now switches off on the key as normal.

Cheers

Excellent..! Great to hear.

Great news Horace!

Hi all,
just want to say many thanks to all who posted here, it has solved my problem. I have just done the reccomended swap to Duraspark distributor and module plus a new relay to supply power from the starter solenoid and triggered by the light blue wire from the ignition switch. Car starts right up nicely, but wont switch off with the key and keeps on running happily after disconnecting the batter - very disconcerting! But after reading this thread and adding the diode in the wire from the generator warning light to the voltage regulator the problem is now solved. Many thanks!
Cheers, Tim.