February 7, 201313 yr comment_646531 I have a problem with my aftermarket tacho, it was woking fine till I jumpstarted my brother car and now it jumps straight to full rpm as soon as you turn the key to the first notch?.And it stays there even when the car is running, I don't get whats happened to cause this, has anyone had this problem or know what might be causing this. Report
February 7, 201313 yr comment_646536 How is it wired in?? Coil negative to the tacho to earth?? Report
February 7, 201313 yr Author comment_646613 How is it wired in?? Coil negative to the tacho to earth?? Yeah, but I don't get why jumpstarting a car made it go crazy. Report
February 8, 201313 yr comment_646616 It might just be coincidence, although you can get voltage spikes from jump-starting. Does it have a 4-6-8cyl selector switch on the back?? You could flick that over and see if it still just goes to max. It doesn't sound hopeful. Report
February 8, 201313 yr Author comment_646711 It might just be coincidence, although you can get voltage spikes from jump-starting. Does it have a 4-6-8cyl selector switch on the back?? You could flick that over and see if it still just goes to max. It doesn't sound hopeful. I have tryed flicking the switch but doesn't make any differance.I was working seconds before I hooked the jumper leads up so I don't think it's a coincidence.I just thought there might be a simple solution before I pull the dash apart. Report
February 9, 201313 yr Author comment_646752 Ok so I pulled the the dash apart to check the wiring.I cut all the wires and tryed connecting the power and eath wires to different sources but same result the tacho just jumps to full the moment you touch the wires together, WTF?.I even pulled the tacho apart to see if the capacitors where swolen or cracked and there all good, so are the solders on the chip I'm stumped as to what is causing this as the tacho work's but not how it should.Anyone got any ideas as to what may be causing this? Report
February 9, 201313 yr comment_646764 I would assume that on a steady 12V current it shouldn't move at all, like turning on the ignition. The tacho works with pulses turning an electromagnet, although they were the old ones and maybe new ones are all electronics. So anyway, I figure if it goes to full revs on any 12V source, its had it I'm afraid. Maybe it is all electronic and something died in there from a voltage spike when you connected or disconnected the leads. Report
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