Sounds like you are reading about half proper reading.

Try looking at the reading in volts. You have to understand what you are looking at. If you could watch the action on a scope tat would slow it down, you would see that one one side of the frequency valve you have battery voltage. The other side is going to pulse at a given frequency. Say the frequency was 1hz (once a second). If you looked at the control side you would see 13v (suppose 13v battery voltage), then zero v as control is pulsed. It wouldcycle 13v, 0v, 13v, 0v, 13v. Now we have to decide how long at 13v and how long at 0v. With a one second cycle, .5sec at 13v and .5sec and 0v would be 50%. A .3sec at 13v and .7sec at 0v will be 70% duty cycle. It is 70% ON because 0v signafies the time the current is applied.

So if you look at this with a voltmeter one will see 6.75v at 50% because voltmeters average. A 70% would be 30% of 13v or 3.9v. Check it out.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician