Re: Under dash "while you're in there" jobs....
Posted: Sun Apr 17, 2022 4:59 pm
notny41 wrote: Fri Apr 15, 2022 12:08 am How many volts does the blink program send to the speedo? I understand that the more frequently the pulse is generated, the faster the speedo will read but is it just 5 volts for each pulse?
The reason I am interested is I would like to try to make a similar signal box as you have to test cruise control computers without having to put them in the car and go for a drive.
Sorry, totally missed this. The speedometer is driven by ground (0 volt) pulses. The factory sender produces 8 ground pulses per revolution of the tire. When not at ground, it's an unconnected/open circuit. So, basically the same as atttaching a single wire to the negative battery terminal and repeatedly tapping that wire against the speedometer's input. Make sense?