30-03-12, 08:19 PM
I wouldn't place too much reliance on the measurement of dc resistance of the coils.. it'll tell you if there's an open circuit, but not much beyond that.
In this case I'd guess the slightly high reading is either contact resistance or that of the leads of the meter.
Coils normally fail in one of two ways, either one winding goes open circuit or one develops a short between adjacent turns... the latter isn't detectable with an ordinary meter, but it'll kill the spark. What's more, the short can be intermittent, often dependent on temperature. Swapping some known good coils in is the only easy way to check unless you've access to test equipment that'll measure mutual inductance.
In this case I'd guess the slightly high reading is either contact resistance or that of the leads of the meter.
Coils normally fail in one of two ways, either one winding goes open circuit or one develops a short between adjacent turns... the latter isn't detectable with an ordinary meter, but it'll kill the spark. What's more, the short can be intermittent, often dependent on temperature. Swapping some known good coils in is the only easy way to check unless you've access to test equipment that'll measure mutual inductance.