digital meter

I don't know if this will help but here goes;
I saw this on a SBM with an Orange box and a reversed pick-up polarity; The Idle timing was Ok, but as soon as I revved it just a little, the strobe on my inductive dial-back timing light, went wild, and the tach read erroneously.
I cut the wires and reversed them close to the connector, then hit the Key. The base timing was way off, but the strobe had returned to normal.And the tach along with it.