How do you test a circuit to see if it's latched or pulsed. Mainly Rear defrost on 04 Dodge Intrepid. I think I figured it out but would like someone to confirm...
Pulsed: when I press the button to activate the rear defrost it sends out a quick pulse to activate defrost relay (negative pulse into a positive system) this would cause the voltage to drop quickly and briefly from 12v +
Latched: When I press the button it sends out a steady negative current to drop the voltage from 12v + for a duration (10min) then turns off and voltage resumes to 12v+
i would think that there is a timer module. When you press the switch, you put a pulsed earth on an input to the timer. The timer then runs and turns on a local light (LED?) and a big switch to connect the battery + to the screen heater. When the timer runs out it it switches every thing off. I hope this helps
Frank
i would think that there is a timer module. When you press the switch, you put a pulsed earth on an input to the timer. The timer then runs and turns on a local light (LED?) and a big switch to connect the battery + to the screen heater. When the timer runs out it it switches every thing off. I hope this helps
Frank
If the switch is latched then you need to push it again to unlatch it. Measure its contacts for a voltage, then push the switch if the voltage changes, then goes back when the push the switch again, its a latching switch. Check all contacts with the button pressed at least 3 times. if all you see (or might not see)is a glitch on your voltmeter when you press the switch then its a momentary contact type. The pulse may be too fast to register on a voltmeter.
Frank