aaaaaaaagggggghhhhhhh!!!!!!!!! ****ing 30yo cars! I'm stumped with this one. when i do anything that requires power ie brake (rear lights coming on) or use a window or fan switch etc my power spikes. on the volt meter it just drops but then comes back on and everything then finctions as normal until i do it again. what the hell could be causing then. it's so annoying when everything just drops out when i brake as my radar detector rebooting constantly is giving me the *****. could it be low charge in the battery? to make matters worse when i got home from work tonight sitting in the carport fiddling to see what else sets it off it just went...and i mean everything. now the only thing that has power whilst the car is off ih full beam, no parkers no interior lights no map light no nothing...i checked the fuses on my drivers side (RHD here people i'm not crazy) kick panel but all are fine. what could this be? i need to sort this asap as thanks to my less then helpful insurance company this car is currently on full time duty as i have no other car and i work nights too. i really dont want to be driving around again coming home from work on the back roads guided by the moonlight

 

Sounds like the common dead battery issue... Get your battery / alternator checked.

 

ok so it's not a battery issue. i had it on charge all last night and now over 2500 i get screamed at with hi voltage from my radar and still get low voltage spikes, infact if i hold my window switch brake light headlights and turn my fan control it can drop right down to 6v :P. to make matters worse i now have no accessory power at all. only when the car is running. i'm gunna go out and replace all the glass fuses on the kick panel and see if maybe i just have some dodgy old fuses in there

 

ok tried that too. i'm now stumped.

 

Yeah, if everything works when the car is running, but things get dodgy just on battery power...I'd get a new battery. You might want to check out your alternator as well.

 

but i have no constant power at all ie no interior lights hazards parkers etc. if i had some power i would have a weak light wouldnt i? or is it hooked up differently in a zed? my thinking was that either my constant power wire has somehow disconnected itself off my battery or when i installed my stereo maybe one of my insulating bits has come off the wire grounding the constant and rendering the whole constant power system useless. pfft i'l go get a battery check tomorrow as well as it's under warranty

 

The battery could have a short in it, or your Voltage Regulator could be toast.

Those are the most likely scenarios.


Rod.

 

i had a battery go totally dead on me on my z31. car would not even take a jump, nothing even lit up when i had jumper cables hooked to it. i thought for sure something was totally screwed, cause the battery was like 5 months old. pulled it and took it to Kragen, they stuck it on the tester, and it was totally fried. got my free warranty replacement, hooked it up, and everything was back to normal.

 

i thought something along those lines but didnt know if the car is fitted with one

 

The 280zx has an internal (inside the alternator) voltage regulator.... thus the reason I advised to check the battery & alternator.

 

i would check your battery ground and check the battery cables. i had a cable rot out inside the insulation. couldn't figure out why i completely lost power while having good grounds.

 

i think it may well be the power cable as I had the battery and alternator checked and all is fine there. great wiring dialemma. just what i want...

 

Sounds like a horrible ground issue to me.. but then,.. I'm a '40 guy, whadda' I know of 280's?

Before I cleaned ALL the connections and sockets, as well as fuse connections, My voltage used to spike as well.
Over time, crud (dialectric gunk) builds up in the connectors and light sockets.. its green an' fuzzy, you cant miss it! mostly caused by 30-plus years of moisture in the air, etc.
Anytime I used the heater fan, brakes, signals anything.. the voltage would spike, then drop.. I also noticed a slight "buzz" to the background of the radio signal... it can also discharge the battery if corroded enough.
I started with the connectors for the lights, and double checked ALL ground cables. we also added a ground strap to the Alt. and a second ground from batt. to the body. this helped as well. Everything now works as normal. I/we cleaned the remainder of the electrical connections I could find, as I find em. a small wire brush. then dialectric spray, seems to do the trick.
No more pulsing lights for me!!

Srry to jump in....

Todd/BC240Z

 

no no thanks! i've always had my system check show up an error for tail lights when my lights are on even though everything worked. now for the dumb *** question...where the hell is my ground on a zed. i've got the single lead off the negative leading to the starter. the thick positive leading to the starter and then a couple of minors leading off into looms

 

can anybody tell me where the main ground is from the battery. please help as i cant find it in the haynes manual either

 

sorted. turns out one of the wires off the old stero harness i thought was a speaker wire contained power so i just took my stereo shroud off and sealed off every wire so there was nothing exposed. thanks for your help

 

turns out it wasn't that. it kept going for another 2 weeks and in the little spare time i had i couldnt fix it. mates dad is an auto electrician and it turned out to be a wire in the fusable link relays. it had a connection but it was corroded so no good. i wouldn't have even thought to check them as I dont even know what they do haha. heads up to anybody that has a similar problem

 

25 year old corroded connections strike again!