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want to upgrade to elec choke


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A suggestion. The 521 electrical system was adequate for a stock 521, when new. It is now over 40 years old.

All the accessories that are on only when the ignition is on, pull current through the original 40 year old ignition switch. Adding an electric choke adds to this load. Not much, but it is constant.


I would consider adding something like this,


to add accessory fuses to the 521 stock system.


That way, you could take the heater motor, and the windshield wiper electrical load out of the ignition switch, as well as the electric choke could be hooked up to one of the circuits in the kit

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Actually, the 521 already has a choke relay. It's called a heater relay. If you look at the schematic, the relay is typically at the top of the page, next to the volt reg and the auto choke connection is at the bottom, next to the coil.


Physically, it's usually a loose spade connector on the firewall near the hood light switch...basically, where it would reach the wire from the choke. The relay is on the pass side of the eng compartment, but I don't know which one off hand....4 wires in a squarish connector?

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That's only in the 1972 521, isn't it? From 1971-back they used manual choke?


The purpose of the Choke Heater relay is not to save current from going thru the switch. It is to prevent the choke from heating up when engine isn't running. For example, if you listen to the radio for a couple of minutes before starting the engine, and mistakenly put it to IGN, then the car won't start on a cold day. To prevent this scenario, the relay only powers the choke when the engine is running. The alternator provides a signal when the engine is running. It is the Neutral Sense wire (N wire). This is a weak signal so a special lower-than-12V relay is used.



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Yep....you're probably right! I kinda had it in my head that my wife's '70 has electric, but I just realized that it's a weber. Most of the other 521's I had were manual choke.


Good stuff gg......I keep coming up wrong posting against you LOL!!! maybe I'll just stop! :)

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Mike, never stop posting!


GGzilla, why does the power for the auto choke relay have to go through the ignition switch? If the engine is not running, Key on, the relay will not energise the choke heater, no alternator signal. Engine off, Key off, still no alternator signal, relay still not energised.

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LOL! Thanks Daniel, but I didn't mean stopping totally.....just stop posting again gg.....I keep coming up wrong!! LOL


I think the prob with using the ign power is that the key can be on and providing power without the engine running when you click it once to on and don't start it. If you take it from the alt, it has to be running.

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