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Where is the ignition ballst and drive resistor?

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Yellowhawk Valley Avatar
walla walla, WA, USA   USA
1969 Triumph Spitfire "Walla Walla"
1969 Triumph Spitfire "Portland"
1972 Triumph Spitfire MkIV "Spokane"
1975 Triumph Spitfire 1500 "Dayton"    & more
The Drive Resistor is an external part if the rest of the original electronic module located inside the dizzy. Most all cars have had the original 79 system removed and replaced by a Lucas system that does not use the DR. (or some other later brand)
The photo shows where it is attached at the back side of the alternator, and the original ignition module connector for the dizzy.
The ignition coil resistor is just a resistance wire, actually the white one shown on the diagrams. The second photo shows the process as defined in the books.

Dan



Edited 1 time(s). Last edit at 2018-02-01 10:44 PM by Yellowhawk Valley.

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1979 post FM95001a-ign.jpg    42.5 KB
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younggene Gene Young
Huntsville, AL, USA   USA
Thanks for the prompt response Paul. The schematic that I used to reach my conclusions was the one in the "Triumph Spitfire Repair Operation Manual" published by BL Cars Limited. It shows a connection from the end of the Ballast Wire (opposite the starter relay) and the "Run Position" (Pin 3, I think) on the Ignition Switch. From Pin 3, there is a wire shown that traces into one of the wires (labeled w) going into the distributor. I take this wire to be the power for the electronics in the dizzy. Another wire (white/blue WU) from the dizzy connects to one end of the Drive Resistor. The other end of the Drive Resistor is shown with a white wire that winds around through the schematic back to the "Run Position" on the Ignition Switch. Of course there's another wire shown from the dizzy to the negative terminal on the coil.

My theory on how this circuitry works depends on the Ignition SW "Run Position" not receiving power through the switch itself when the Sw is in the "Start" position. Power is reapplied to the Run terminal through the SW when placed in the "Run Position". In the "Run Position", there is 12 volts on both ends of the Ballast Wire and no current flows through the Ballast Wire".

Does anyone have a proven schematic for the wiring of a 1979 Spitfire 1500? I have a lot of other electrical issues to work out.

Thanks, Gene

Manana Avatar
Manana Steve Wten
Thornhill, ON, Canada   CAN
Gene, when installing my Pertronix set-up I decided I had to learn exactly how things worked so I wouldn't bugger it up. You may be past this point, and get it better than I did, but back then I put this together to hopefully better illustrate how things worked on my '78.

http://stevew10.wixsite.com/spit16/ballast-wire-system

Hope it helps.



Steve
http://stevew10.wix.com/spit16

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Yellowhawk Valley Avatar
walla walla, WA, USA   USA
1969 Triumph Spitfire "Walla Walla"
1969 Triumph Spitfire "Portland"
1972 Triumph Spitfire MkIV "Spokane"
1975 Triumph Spitfire 1500 "Dayton"    & more
The section I posted above came from the factory manual. Make note that there is a slight difference between the diagrams in different factory manuals and the original owners manuals, especially a difference between pre FM95001 diagrams and the post FM95001 diagrams. The actual working of the system is the same, just the layout changed, and the wiring from the Drive Resistor to the fan relay system on the white wire. That part does not have an effect on the ignition wiring.

Make special note of the error of the numbering or identification of the itms 74 and 75 on the three year diagram.

Dan

The .pdf document will be much easier to read as it will blow up large and remain visible. Sorry about the other one - forgot about the loss of detail. da



Edited 1 time(s). Last edit at 2018-02-02 10:40 PM by Yellowhawk Valley.


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1977,1978,1979 early RepMan FM60001to 95000 LH.jpg    58.3 KB
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79bluespit Avatar
79bluespit Rick Lazio
Burlington, ON, Canada   CAN
You have an interesting prob Bob. A 80 spit has a balast built into the wire feeding the coil. So only when cranking shud you read 12v. With ignition on but not cranking it shud read 6v to 9v. Yours reads 12v so a po removed the ballast. So using s 12v coil would then be correct. However as one mentioned earlier, if you are reading 12v on both sides of coil you have a grounding issue or perhaps in-correct wiring that a po did. In that case its difficult to help.

The drive resistor is not likely your problem. TBH no one really knows what the drive resistor does... I've searched these forums on it and most ppl misunderstand it as the ballast resistor or their explanation on it is in-complete, do I still don't truly know what its purpose was. However....make sure the two wires connecting to the DR are taped off. I've heard here that if there is a short it will melt ur ignition harness somewhere along the line.

65or66 Jim B
Lake village, IN, USA   USA
1965 Triumph Spitfire MkII
1973 Triumph Spitfire 1500 "Jusanudda Munny Pit"
I believe parts of many early electronic ignitions (the actual electronics inside) can only operate on 5 volts, or less. That external (drive) resistor is there to drop the voltage going to the ignition down from 12 volts to a level that will not fry the electronics inside. Bypass the external resistor on the alternator, fry the ignition. Don't know if the Crane has a similar requirement.

Doug in Vegas Avatar
Doug in Vegas Douglas D
Las Vegas, NV, USA   USA
The drive resistor was removed by dealers. The wires were abandoned or removed.

Mine got the Lucas upgrade.

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TheZster Avatar
TheZster Steven Z
SAINT LOUIS, MO, USA   USA
1978 Triumph 1500 "BLK-BRY"
trouble with a 40 +/- year old vehicle.... who knows what the PO(s) did in the past..... My 78 had a resistor feeding the coil dropping voltage to about 6 volts - which I bypassed to install a 12 volt required coil (Pertronix)..... I've looked high and low - and can't find a drive resistor.....

40 years from now - the newest owner will be on this forum - cussing out me - as the PO.... LOL.....

Z

Manana Avatar
Manana Steve Wten
Thornhill, ON, Canada   CAN
That's why it's so important to understand the system. Chasing wire is easy..... if you know what your looking for.



Steve
http://stevew10.wix.com/spit16

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TheZster Avatar
TheZster Steven Z
SAINT LOUIS, MO, USA   USA
1978 Triumph 1500 "BLK-BRY"
In reply to # 1511121 by Manana That's why it's so important to understand the system. Chasing wire is easy..... if you know what your looking for.

Dammit - he's right yet again....... Chasing wire is easy..... On the other hand.... unwrapping that electrical tape binding on a bundle - put there by a PO - then figuring out what was cut out/added...can be a scary proposition.....LOL

BTW - Steve's schematic made rewiring my new coil easy..... Thanks guy...

Hey - if we wanted easy - we would have bought a new car.....


Z



Edited 1 time(s). Last edit at 2018-02-02 06:19 PM by TheZster.

spitfire50 Avatar
spitfire50 Paul Mugford
Rochester, N.H., USA   USA
Guys,
Believe me Spitfire wiring even after 40+ years of DPO action is easy. Modern car wiring can be a real headache.
Don't think you can just swap in a different radio. The radio is part of a network and changing it breaks the net. The other things on the net won't work either.
Adding a hitch? You'll be lucky if software can be loaded to make the electronics tolerate the added lights.
Is this wire a signal in to the module, a signal out of it, power going in, or coming out? Even the diagram may not make it clear.
All the best,
Paul

79bluespit Avatar
79bluespit Rick Lazio
Burlington, ON, Canada   CAN
Totally agree with that Paul. Computer chips have made life easier yet more disposable.

An author wrote an article asking which classic car was first to suffer lack of collector interest due to technology. I think it was the BMW 850 and 740. The 850 by now shud have risen in value, yet remains cheap as chips. To fix or repair either of those cars is a detergent. Can u imagine fixing a murcialago 20 yes from now?

Doug in Vegas Avatar
Doug in Vegas Douglas D
Las Vegas, NV, USA   USA
The funny thing is Lucas wasn't considered "disposable" at the time.

Brad.Cogan Avatar
Brad.Cogan Bradley Cogan
RAF Cosford, Shropshire, UK   GBR
1977 Triumph Spitfire 1500 "Wray"
1989 Toyota MR2 "Coral"
2007 Fiat Grande Punto "Pepper"
Do you need 12V or 6V for your ignition system? If it's 12V then no ballast is needed. If it's 6V you will need one.

My Spitfire had a pink/white wire which was a resistor wire but I bypassed it when I upgraded to electronic ignition. Some don't have this and need a separate resistor. I'm probably stating the obvious here though.



Brad Cogan

1977 Triumph Spitfire 1500 'Wray'
1989 Toyota MR2 Mk1b AW11 1600 twin cam
2007 Fiat Grande Punto Active 1.2 'Pepper'

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