The controller has a little switch next to the sockets. What is it for, I do not find anything about it in the manual. The push-button switch is to disable the lock up, "on" means it is going to lock at the speed set with the knob, right?
I don't know either but my guess is it either has to do with testing or it may cut the pulses in half if you have a speedo that reads really fast. The instructions I found indicate moving it to the left in the orientation you show is the correct place to plug it.
This should help... https://documents.holley.com/70244.pdf ... but I didn't see this switch mentioned except in the diagram: ... unless it's this model... ... but I did turn up this snippet " "Figure 1" of the instruction sheet has a notation to slide the switch to the right (IF using mechanical speedometer input.) You MUST slide this switch to your right or the unit will NOT function." Which implies it's an enable/disable switch. Means you have a 50/50 chance of getting it right
Thanks guys, still don't know what the purpose of the switch is, but it makes the unit work when slided to the right. Guess that all one needs to know .