Test coil

[KSmith]

1975 GL The 3 and 4 cylinders were not firing. I bench the coil primary and both coils showed 2.7 ohms. The secondary test did not have any reading when I put the test probes on both spark plug wires ends. Did I do something wrong. I know one of the coils was work fine.

[gltriker]

14,500 ohms is secondary resistance specification without the spark plug caps installed

[KSmith]

Thank you for the quick response! What is your method of testing the secondary coil? I thought you were supposed to test it by the ends of the spark plug wires without the cap on. But I had zero ohm showing like there was nothing there.

[gltriker]

https://www.randakksblog.com/coil-testi ... t-options/

[KSmith]

Thank you for your help,
The two primary both read 2.8
Spark Plug wires with out the plug caps off the end of the wire measured for wire 1&2 14.8 wires 3 & 4 14.7
All 4 Plug Caps measured different. 1 = 29, 2 = 5, 3 = 14.7 & 4 = 14.3

I believe the coils and the wires are good. I seems like the plug caps were old. I ordered a new set of plug caps.

[gltriker]

You are very welcome

[redglbx]

FYI,, the plug caps should read less than 5k ohms when measured across them .

[KSmith]

Thanks for the feed back. I am not a train mechanic and electrical issues could be such a challenge. But with the help in following the procedure step-by-step, I was able to figure out that the caps were failing.
Today I’ll put the coils back in and clean everything up and wait for my caps to come in the mail.
Thanks again