10HBMartian Posted February 22, 2014 Share Posted February 22, 2014 ok so a week ago i tried to wire in a radio in my 77 280z. it ended up not working right so i just pulled it back out. a few days later it failed to start. i charged the battery all night then it was working properly for a few more days. then it just wouldnt crank up unless jumped. i replaced the battery and alternator. and checked connections everywhere. it ran fine for a while. then the other day it drained itself dry. i jumped it. it ran fine for a few then slowly lost charge. every since i put on the new alternator it has the charge light on on the dash. its just a stock 280z alternator from advanced auto. i unplugged every thing under the dash that wasnt necissary like the heater blower, radio harness just in case it had a short. i looked at the little relay onder the passenger seat too. it looked fine no shorts. im at my end with this electrical monster and any ideas would help greatly. i looked around on here but nothing specific to my case turned up. thanks Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted February 22, 2014 Share Posted February 22, 2014 Did you trace the charging circuit back from the alternator? Quote Link to comment Share on other sites More sharing options...
beermanpete Posted February 22, 2014 Share Posted February 22, 2014 It sounds like the alternator is not charging. Check the system voltage when the engine is running. At idle is should be about 12.5 to 13 volts. When you race the engine the voltage should rise to about 14.5 to 15 volts. Quote Link to comment Share on other sites More sharing options...
WRC17 Posted February 23, 2014 Share Posted February 23, 2014 Have you checked the fusible links? I know they can be troublesome. Quote Link to comment Share on other sites More sharing options...
jhm Posted February 23, 2014 Share Posted February 23, 2014 Sounds like your problems started when you were installing the radio? If so, I'd start there....check all the connections and leads that you may have worked with during the installation. If your alternator is charging correctly and the battery is still draining, there's a slow drain somewhere, even when the ignition is off. Good luck with it and be sure to post your results! Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 23, 2014 Share Posted February 23, 2014 ok so a week ago i tried to wire in a radio in my 77 280z. ...... its just a stock 280z alternator from advanced auto. Are you sure it's an externally regulated alternator? The 78 280Z's had internal regulation, your 77 probably came with external. Which also makes one wonder about the external regulator. Quote Link to comment Share on other sites More sharing options...
9rider Posted February 23, 2014 Share Posted February 23, 2014 I could be wrong, how about antenna switch? Mine has a switch on pass side to control antenna up and down, and could drain battery if it shorted. Quote Link to comment Share on other sites More sharing options...
4.6StangRage Posted February 23, 2014 Share Posted February 23, 2014 The best and most definitive way of determining the parasitic draw would be to connect a ammeter inline between the ground terminal and the battery. Record the results before doing anything. Next disconnect the alternator (notate if there is a major drop in amps) DO NOT RECONNECT Next, Pull each fuse while noting any drops in amps DO NOT RE-INSTALL FUSES UNTIL YOU DETERMINE WHICH CIRCUIT IS IN QUESTION. I would do it this way because there could be different variables causing the drop. This method makes it so you dont get all wrapped up and running in circles and stuff. Quote Link to comment Share on other sites More sharing options...
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