shaheed

so i re-hooked up my zeitronix, which i had been using in another car, today. i'm using a simple three wire hookup (i don't log the tps signal). red wire to DME #18, green wire to DME #21, black wire to ground, which is how i had it hooked up before. cranked the car, it attempted to start then died, few more times same thing. unplugged the zeitronix harness (wires still soldered on) and the car starts right away. i tried plugging the zeitronix back in while the car was running (ok, ok i realise that's probably not the smartest thing to do) and the car keeps running and the zeitronix works properly. turn the car off and it will not start again. unplug the harness and it starts fine. i'm stumped, since i'm basically only tapping RPM wire i don't understand why this would prevent the car from starting even if the zeitronix box itself is bad. any ideas?

Tom M'Guinn

Something in the box must be taking pin 21 to ground or +v when cranking the starter....

shaheed

but wouldn't it have the same effect (ie taking it to ground) when the car is running?

Tom M'Guinn

Well, you'd think, but I had an old ARC2 that would pull down the AFM signal when the motor cranked -- that took a while to find... Check for spark when you crank with the box plugged in. Or, if you happen to have an o-scope...