Testing primary and secondary on coil

OK this is a stupid question I know. My Haynes manual and all the past posts here give me the #'s to look for, but...

Which terminal is #1? #15(primary), and #4? Which is which?????

I have .7ohm between the two outside ones
and 665 ohms between the middle (coil plug wire) and either outside one.

I assume my coil is good its within specs but which are which????

Thanks

Shawn

[This message has been edited by davis911s (edited 05-14-2001).]

Shawn,

Referring to the following diagram:
http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_1973_CIS_Part2.jpg

The diagram terminals are #1, #4, and #15, where #1 is ground, #15 is the 'high' side of the primary, and #4 is the output side of the secondary. The pnly problem is, those aren't the correct makings on the Bosch 0.221.121.001 CDI coil! The coil has terminals #1 and #4 that match, and terminal 'A' instead of #15 for the 'high' side of the primary.

Your resistance readings do fall within the factory specs of 0.4 to 0.6 Ohms for the primary if you take into account that most multimeters are not really very accurate on the 1-2 Ohm range, due to variations in test leads! Short your test leads together, then subtract that value you read from the 0.7 Ohm reading to get the actual value of the primary. And, you are within the spec of 650-790 Ohms for the secondary!

The CDI unit should always have at least 11 Volts at the supply terminal 'B', and the current draw/drain should be from 1.0 to 1.9 Amps.


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Warren Hall
1973 911S Targa

Thanks again Warren

How can I test the output of the CDI? Is this the figures when the key is at the start position?

I found a problem with my CDI A-D reading was good 3348ohms, B-C was good 99.7ohms

But when I put it in the car D-ground was 1000ohms supposed to be 0. This is my starting problem. Would this be a bad ground?

Help

Shawn

Well, that certainly sounds like a bad ground! You may want to unbolt the entire relay/regulator/CDI console from the fender/firewall ... and do some cleaning of all grounds! Remove the CDI unit from the console and clean the bare spot where the paint was masked at the factory -- the gronding point for the CDI-unit. Also, clean the ground terminals at the CDI-unit frame, coil, and distributor. The coil should be unbolted from the fan housing, and clean both ends of the short Brown coil ground wire, as well as the terminals of the coil, after un-bolting both nuts, wire lugs, and washers, too.

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Warren Hall
1973 911S Targa

Will do! You think it is more the CDI etc more than the engine ground?

There is a small ground wire wrapped up with the 14 pin connector, It is loose, I don't know which of the two wires that are there it is supposed to attach to , anyone know?

I'll keep all posted.

Shawn

[This message has been edited by davis911s (edited 05-14-2001).]

OK I fixed the "bad ground" it was actually the ground connector on the CDI box itself. It was broken at the attachment point.

Soldered it up and good. Still NO SPARK! I have retested the CDI connections this time the A-D is reading 2800ohms give or take, specs are 3300ohms does this seem weird?

I am at aloss with this, but it is part of the fun for me of owning o P-car.

Shawn