View Single Post
mysocal911 mysocal911 is online now
Registered
 
Join Date: Feb 2014
Location: Lomita, CA
Posts: 2,738
Quote:
Originally Posted by Jeremy911T View Post

Just so I am straight on the terminology, when you say "terminal C" do you mean the plug side that connects into "pin C" on the CDI unit itself? Is that correct?
With the key-off, disconnect the CDI plug and measure the resistance at terminal C to the ground pin (the one for the body of the CDI).
of the
Quote:
Originally Posted by Jeremy911T View Post
So the first test you suggested, "You need to power-up the CDI out of the car and measure the "C" pin of the CDI." Can I place an alligator clip from the B terminal on the plug to the B pin on the CDI unit to give it power and then measure the volts at the C pin on the CDI unit? I am assuming that the C pin should measure 12 volts.
Correct. The CDI for this test is still mounted with just one connection, 12V to the B pin.

Quote:
Originally Posted by Jeremy911T View Post
For the second test, "You need to disconnect the CDI from its connector and measure terminal "C" with a meter to ground (CDI case) for continuity, key-off". After pulling the plug off the CDI and with the key off, I would measure for continuity from the C terminal (plug side) to the CDI case.

Then with the key still off, measure the resistance (ohms) from the C pin on the CDI unit to ground, in this case the CDI case.
Correct. You should measure either 100 ohms or 30 ohms.

Quote:
Originally Posted by Jeremy911T View Post
When I measure to ground on the CDI case, are you referring to the ground pin on the CDI unit in front of the A, B, and C pins or anywhere on the case itself? I am assuming the case acts as a ground. Sorry about all the questions. I am a little new with all the terminology and I want to make sure I am testing correctly.
Yes

Quote:
Originally Posted by Jeremy911T View Post
Could I check the individual wires from the CDI to the coil and distributor by bypassing them with alligator clips. For example, I connect a clip from the B plug (power source) to the B pin (CDI unit). Then I place alligator clip from the C pin (CDI unit) to the connection on the distributor (on the common connection with the tach wire). Another alligator clip from the A pin (CDI unit) to the coil. Another clip could ground the CDI unit. If the car runs I know I have a bad C or A wire and the CDI is ok. Then it is just a process of putting one of the wires in question back in the circuit to find the bad one. If it still doesn't spark after bypassing the B and C wires it would tell us that the CDI unit is bad. Is my reasoning sound or am I missing something?
First, do the above suggested tests.
__________________
Dave

Last edited by mysocal911; 02-27-2022 at 01:30 PM..
Old 02-27-2022, 08:47 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #16 (permalink)