I am rewiring my GTD. It has a MSD system in it. It starts and run fine but continues to run when I turn the key OFF. I have to pull the coil wire off the switch to stop it. Any ideas?
Engine continues to run
- Thread starter Sam McDowell
- Start date
You get a little Diode thingy with the 6A parts kit, this goes in the alternator circuit to prevent feedback which keeps the ignition live. If you don't have the MSD instruction sheet have a look at the MSD website, it should tell you where it goes, if not I can let you know tomorrow.
Mike
Mike
Thanx Mike, Jac & Ron. That diode makes sense to me. I inherited this system and will need to research it more. I have the installation papers, but any part numbers or diagrams would be helpful.
The wiring project is working so far, engine cranks, horn & turn signals work. One wire at a time...
The wiring project is working so far, engine cranks, horn & turn signals work. One wire at a time...
Sam,
best to go to www.msdignition.com, go to trouble shooting and it's all there under "engine run on "
Mike
best to go to www.msdignition.com, go to trouble shooting and it's all there under "engine run on "
Mike
By George I think that is it.:idea:
Thanx Mike.
Thanx Mike.
Dimi Terleckyj
Lifetime Supporter
Hi all
One thing that is a trick for new players is that the cooling fans ,when running, are motors but become generators when driven by the air passing through them.
Also if they are running when you turn off the motor they will generate power which will back feed and keep your ignition live.
They also require diodes.
Dimi
One thing that is a trick for new players is that the cooling fans ,when running, are motors but become generators when driven by the air passing through them.
Also if they are running when you turn off the motor they will generate power which will back feed and keep your ignition live.
They also require diodes.
Dimi
Seymour Snerd
Lifetime Supporter
That means we're all driving wind-power hybrids! Do we get a tax credit?
There is an inbuilt design flaw in the factory supplied GTD wiring loom. This may not apply to your situation as you did not provide the info necessary to determine it but it goes as follows;
It you are running your car on a hot day, and to keep the engine temps cool, you manually switch the fan override on, should the water temp rise enough even then so that the automatic cooling fan switch temperature is exceeded ie would have turned the fans on anyway if you had not manually put them on, you will not be able to turn your engine off! No idea why it does this but it does do it! Bizarre. Fortuanetly it is quite a rare occurrance and also you just switch off the fan override and the engine dies as it should.
It you are running your car on a hot day, and to keep the engine temps cool, you manually switch the fan override on, should the water temp rise enough even then so that the automatic cooling fan switch temperature is exceeded ie would have turned the fans on anyway if you had not manually put them on, you will not be able to turn your engine off! No idea why it does this but it does do it! Bizarre. Fortuanetly it is quite a rare occurrance and also you just switch off the fan override and the engine dies as it should.
Usually the fans are switched via relais. The relais is usually activated by the thermostat. The Thermostat is either switching the ground wire or the positive of the relais solenoid. The positive feed for this is a permanent power (30)lead. If you now have a one relais solution your manual override is running parallel to this permanent supply. The manual override is feed by a ignition on power lead ( 15) as is the ignition circuit. So the coincidence you have now is the following. The ignition coil ( or MSD switch on) lead is connected to the same power feed as the manual fan overrun ( this connection is likely before the fusebox or via the ignition key switch). So if now the thermostat is activating the 30 power to the fan relais, the power is feed back via the maual overrun switch to the ignition coil wire and thus the engine keeps on running.
Solution.
Implement a second relais for the fans, one for the automatic switch on and one for the manual override. THis separetes this two circuits and should solve your engine running issue.
SAM:
THere are two power wires from the MSD, the red one ( havier wire) should directly go to battery ( or positive lead of starter solenoid). THe small red one should be go to your ignition switch. If you activate this small red one via the key switch only the likelyness is high that via this keay switch you are connected to other switched power leads ( usually this key switches have just one power in and two or three power out connections) also via the fuse box. It seems high likely that one of this other sources is connected also to permanent nonswitched power and is feeding back. Typical sources for this are, hazard switch, parking lights, fans. All of this need to run without the key switch on, but also have a connection to switched power. Check this out and i bet you will find the solution. Other solution would be to have an additional toggle switch installed in the white switch wire of the MSD to be able to switch it off without the need to turn the key switch off. Is helpful in some cases anyway, if you want to turn the engine without having it starting ( preoiling).
TOM
Last edited:
First I have to say thanx to all the great advice to the new guy.
The MSD web site addressed the "run on" problem. They say put a 1amp/100volt diode in the key-coil line. That is a dinky little piece of electronics. But I'll try it.
I had put a simple on/off toggle in the line at the ignition switch that kills the coil. It works. It could be hidden as an anti theft switch.
I will have to work on the fan overide. The wiring harness I have does not have that provision.
Thanx again,
Sam
The MSD web site addressed the "run on" problem. They say put a 1amp/100volt diode in the key-coil line. That is a dinky little piece of electronics. But I'll try it.
I had put a simple on/off toggle in the line at the ignition switch that kills the coil. It works. It could be hidden as an anti theft switch.
I will have to work on the fan overide. The wiring harness I have does not have that provision.
Thanx again,
Sam
Sam I have not looked into the MSD website, but it sounds not correct to put the diode into the key coil line, which i define as the small red wire of the MSD which is supposed to be used as a switch on and off line ( not the main power line). It wont be of any help there. The current need to flow into the direction of the ignition box so the direction you put the diode in is clear, and there is nothing flowing back from the ignbox.
The diode should suppress a current which flows over the regulator of the alternator backwards via the charge control light or from any other permanent source. The fact that it works with your toggleswitch is clear indication that there is current flowing in front of your key ignition switch to this line. if you measure it you probably find out that your ignition is powered all the time and the ignition key is just switching the power to your start button on and off. You do somewhere have a connection from the permanent power lead ( charging lead from alternator to battery or direct from battery) to your switched powerleads.
TOM
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