marinez Posted August 30, 2016 Share Posted August 30, 2016 Ok...10/75 280z. 327 with HEI. Tach has been recalibrated, now trying to hook up correct wires. Have brown, green, red under hood at former distributor harness. Prior owner used black/white for coil power, 12v ignition hot. Thoughts? Quote Link to comment Share on other sites More sharing options...
NewZed Posted August 30, 2016 Share Posted August 30, 2016 Brown, green and red would be the VR sensor wires that run to the ignition module in the cabin. The blue wire from the coil negative terminal (through the ballast) is the tach trigger. Quote Link to comment Share on other sites More sharing options...
marinez Posted August 30, 2016 Author Share Posted August 30, 2016 I might have to hug you. Quote Link to comment Share on other sites More sharing options...
marinez Posted August 30, 2016 Author Share Posted August 30, 2016 Well...nothing. Quote Link to comment Share on other sites More sharing options...
NewZed Posted August 30, 2016 Share Posted August 30, 2016 No hug? You need to add some detail. There are some considerations and some simple tests you can do. It's not even clear what you mean by nothing. Could mean no blue wire, could mean blue wire doesn't work. Could be the resistor fell out. Quote Link to comment Share on other sites More sharing options...
marinez Posted August 31, 2016 Author Share Posted August 31, 2016 Sorry Zed. No signal from the blue wire. Any idea what the end connector might look like? I just found another blue wire. Quote Link to comment Share on other sites More sharing options...
NewZed Posted August 31, 2016 Share Posted August 31, 2016 Do you know what the signal is? Did you measure voltage at the tach end of the blue wire? Have you looked at the wiring diagram? Really, the basics are pretty easy with a meter. Get everything connected correctly, then you can focus on why the needle doesn't move. With a meter you don't have to worry about what the terminals look like. Who recalibrated your tach, and is it the stock 1975 280Z tach? Are you using the stock 280Z harness connection at the tach? Aftermarket tachs can have different wiring schemes. Quote Link to comment Share on other sites More sharing options...
marinez Posted August 31, 2016 Author Share Posted August 31, 2016 Stock tach with pot reset.Stock harness at rear of tach. Quote Link to comment Share on other sites More sharing options...
marinez Posted August 31, 2016 Author Share Posted August 31, 2016 Shoot. I forgot to ask what the correct voltages should be. Quote Link to comment Share on other sites More sharing options...
NewZed Posted August 31, 2016 Share Posted August 31, 2016 With the key On you should see battery voltage at the tach end of the wire if it's connected to the coil negative terminal as it should be. The 280Z tach just counts the voltage pulses on the negative post of the coil as the coil charges and discharges. Quote Link to comment Share on other sites More sharing options...
marinez Posted August 31, 2016 Author Share Posted August 31, 2016 Ok so remember this is HEI. Big cap. Quote Link to comment Share on other sites More sharing options...
marinez Posted August 31, 2016 Author Share Posted August 31, 2016 Crud.. ok...so essentially I have to connect the HEI to the factory harness. I'm concerned the tach itself isn't receiving power. Quote Link to comment Share on other sites More sharing options...
NewZed Posted August 31, 2016 Share Posted August 31, 2016 There's a tach output terminal on the typical HEI distributor from what I see on the old interweb. It's probably just a branch from the coil negative post. Easy to check. Quote Link to comment Share on other sites More sharing options...
marinez Posted August 31, 2016 Author Share Posted August 31, 2016 That's live and working. Quote Link to comment Share on other sites More sharing options...
NewZed Posted August 31, 2016 Share Posted August 31, 2016 I don't know what means. But, good luck with it. I have a GM HEI system, module and coil, on my L6, using the 280Z VR signal. My tach doesn't work without a condenser on the negative terminal wire. Quote Link to comment Share on other sites More sharing options...
marinez Posted August 31, 2016 Author Share Posted August 31, 2016 Ok...I just need to establish if the tach has power. I have signal from the hei. Quote Link to comment Share on other sites More sharing options...
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