Charging problems

[j-a-y]

Ok well i went out in my supra last weekend, drove to the petrol station,fine started it up and all dash lights come on and then dims ah!! So ok its probly the alternater, today i put a ueased one on on that i know that works i go to start it and i get the same thing???? Dash light on and then dims and battrey gose flat, not sure where to look next now can some one help please.

Edited September 3, 2016 by j-a-y (see edit history)

[GreaseMonkey]

Poss worth checking the items mentioned in this thread and on some others like this Under Alternator/ Battery/ Charging in the search function. sounds like a possible wiring or connection issue like a poor ground/ earth maybe?.

http://www.mkivsupra.net/vbb/showthread.php?303990-Dash-warning-lights/page2&highlight=battery+warning+light

[Dnk]

Is the battery ok ?

[j-a-y]

Yes the battery is good and i tried another one today, i put it on started it up and it seems ok for 5 mins or so then the dash lights come on again, so i though il unplug the 3 pin plug and see what happens well when i unplugged it the lights on the dash went out but where was a strangn wizzing or hissing sound when i plug it back in witch iv never heard this from my car before, then i switch it of then restarted it but this time the revs were going up n down??? Now i dont know what to think.

Edited September 4, 2016 by j-a-y (see edit history)

[Nic]

then i switch it of then restarted it but this time the revs were going up n down???

 

That *may* be because the ECU has been reset, it'll take a short drive for the ECU to relearn some of the settings which might cure the idle hunting.

[j-a-y]

I dont think so in this case, it's definitly a charging isue i think as the battary was not getting charged the power to the ecu was week , how ever i did change over the ecu but still getting the same thing.

[j-a-y]

Just an up date, it was the alternater lol so i had it referb, £75.