280driver Posted October 15, 2019 Share Posted October 15, 2019 I disconnected an aftermarket amplifier in my ‘75 280Z this weekend. Later that day, the dash and running lights went out. Today, the tach and gas gauge stopped working. Did disconnecting the amp cause this or is it just coincidence? Quote Link to comment Share on other sites More sharing options...
jhm Posted October 15, 2019 Share Posted October 15, 2019 My guess would be that the amp was installed somewhere in your dash; and in disconnecting it, you disturbed some other circuit(s) which apparently affected multiple components....could've been 12V lines, or grounds, or signal feed lines, or some combination of all three. Don you have full schematics for your car? If not, you can download them for free from Xenonzcar.com. Worth their weight in gold for troubleshooting issues exactly like the ones you're currently experiencing. Quote Link to comment Share on other sites More sharing options...
280driver Posted October 15, 2019 Author Share Posted October 15, 2019 Any chance the problems would resolve if I hooked them amp back up? Quote Link to comment Share on other sites More sharing options...
silverado22c Posted October 15, 2019 Share Posted October 15, 2019 Did you just disconnect connectors on the amp or did you cut wires to remove the amp? We can't tell you if easy to connect back up and for your issues to go away, because you didn't state how you removed the amp. Providing pictures are always best the more vague questions are. You might have had a 12 volt ignition source that was connected to the amp when the vehicle was in accessory or on position. Quote Link to comment Share on other sites More sharing options...
280driver Posted October 15, 2019 Author Share Posted October 15, 2019 I didn’t cut anything. The wires for the AMP ran from the dash area down the floor board to the amp that was actually located behind the passenger seat. I simply unscrewed the wires (power, ground, speakers, etc.) and pulled the amp out. I left the wires alone. They are still just under the carpet. Quote Link to comment Share on other sites More sharing options...
Whitley_280z_2+2 Posted October 15, 2019 Share Posted October 15, 2019 I would start by checking the fuses. The only reason I can think of for circuits going out like that is a loose connection or a loose +12V wire causing a short which would blow a fuse. If you still have the glass type fuses they are super easy to check with a multimeter. Good luck 1 Quote Link to comment Share on other sites More sharing options...
280driver Posted October 15, 2019 Author Share Posted October 15, 2019 That’s what I was thanking. The power wire touched the metal floorboard and shorted everything. The only fuses I know of are on the right side of the passenger firewall. I checked those and they are good. Are there other fuses? Quote Link to comment Share on other sites More sharing options...
G-Tech Posted October 15, 2019 Share Posted October 15, 2019 make sure the main power wire (larger red wire) for the amp is disconnected from the battery or atleast the inline fuse should be pulled you should see it under the hood, running directly to the battery. inline fuse should be within a foot of the battery. tape the ends of all the wires you took off the amp, including the RCA cables. silverado22c has a good point about the ignition wire that turns the amp on. its mostlikly spliced into a existing 12v ignition source.it should just be a small blue wire. make sure thats tapped up. Quote Link to comment Share on other sites More sharing options...
jhm Posted October 15, 2019 Share Posted October 15, 2019 You can certainly try hooking the amp back up to see if anything changes. There's no telling what crazy wiring mods previous owners have down to the car. The main fuse panel in the passenger footwell area are the only fuses you need to check, unless someone has added more fuses throughout the various harnesses over the years. If the amp was somehow wired so as to affect the operation of ANY other components (e.g. your dash lights, your gauges, etc); I'd suggest fixing that immediately. Shouldn't work that way. Good luck with it. Quote Link to comment Share on other sites More sharing options...
280driver Posted October 15, 2019 Author Share Posted October 15, 2019 The fuse from the battery to the amp was blown. I pulled it. Could whatever blow that fuse have done something to the dash, tach and fuel gauge? All the fuses in the fuse box are fine. Quote Link to comment Share on other sites More sharing options...
G-Tech Posted October 15, 2019 Share Posted October 15, 2019 What about the blue ignition wire going to the amp? Amps blow fuses often. That wire is also ran directly to the amp so I dont think that would be it...my money is on the ignition wire grounding out on the floor or slim chance that the RCA cables are grounding out if you just have them touching the floor Quote Link to comment Share on other sites More sharing options...
280driver Posted October 15, 2019 Author Share Posted October 15, 2019 30 minutes ago, G-Tech said: What about the blue ignition wire going to the amp? Amps blow fuses often. That wire is also ran directly to the amp so I dont think that would be it...my money is on the ignition wire grounding out on the floor or slim chance that the RCA cables are grounding out if you just have them touching the floor Assuming that’s the issue, it there a fuse that would be effected that’s not in the box on the passenger side or a way to “reset” things? Quote Link to comment Share on other sites More sharing options...
280driver Posted October 15, 2019 Author Share Posted October 15, 2019 Here’s the back of the amp. Quote Link to comment Share on other sites More sharing options...
G-Tech Posted October 15, 2019 Share Posted October 15, 2019 Mostlikly someone just spliced it in with an exciting wire. Those ignition wires are "not that important " so most people are cruel with the way they wire them in...try tapping it, and put some tape on the RCA cables also. See what that does Quote Link to comment Share on other sites More sharing options...
G-Tech Posted October 15, 2019 Share Posted October 15, 2019 more that i think about it. remembering my old stereo days. the blue/remote wire is what turns the amp on and it should come right from the stereo, the RCA's also come right from the stereo. electrical can be a little crazy to try to figure out. i still say tape off any electrical wire that came off the amp and see what that does. its just an easy thing to 1st try and go from there if that doesnt work Quote Link to comment Share on other sites More sharing options...
bradyzq Posted October 20, 2019 Share Posted October 20, 2019 When removing added components like amps, phones, alarms, remote starters, etc, etc, it's better to remove the wiring at its source, not just remove the component. That way you discover the sometimes "creative" ways the PO installed it right away, and you can return the wiring to stock. It sometimes takes a bit of wire tracing time, but it's worth it. Quote Link to comment Share on other sites More sharing options...
280driver Posted November 2, 2019 Author Share Posted November 2, 2019 So I started the car today and both tech and gas gauge are now working. No clue why but I’m happy. Quote Link to comment Share on other sites More sharing options...
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