Thread: +12 V Battery/Constant Fuse?

Ok first the issue. I have a 1992 Sentra and the dome light, trunk light, hazard lights, constant +12v wire in the radio harness doesnt work and the clock in the cluster resets every time I open then close the door. Oh and the warning buzzer that the key are still in ignition doesnt work either. I've been trying to figure out what could be the issue, all the fuses there under the dash seem fine, but then I came across a post on a Subaru forum where a guy had a similar problem in his car with a bunch of thing like that (that require constant power even when car is off) not working. Someone suggested that it was a 20 Amp fuse under the hood somewhere labeled "Backup" that must have blown. Is there any fuse or something like this that i could check for to see if this is my issue as well? I'm really confused at whats going on. Once when i removed my old (stock) tape deck, i plugged in a aftermarket head unit and the dome light and clock were working again but I was only testing it and when I went to try again with another head unit no dice.

The only way i got the head unit working this time was putting both the constant and switched [meaning power goes thru when i switch on the ignition] wires from the head unit to the [blue] switched wire in the car as the constant [red/black] wire didnt seem to have power coming through it.

Any idea whats going on here?

I think you are missing a 12v constant somewhere. The clock and chime are on the same circuit, not sure what else is on it. You are going to have to browse through the FSM to find out which wire it is and find out why it does not have power.

When you say missing a 12v constant, what do you mean? Bad fuse perhaps or a bad wire..? Could it be some type of fusible link somewhere under the hood?

Heres a weird thing. I had heard from someone who had the clock/dome light not working issue and when they swapped the fuse in the back of their radio it fixed it. When i removed my stock one and just test out one i had sitting around (all i did was plug in wires to the Switched and Constant +12v wires, which are the blue and red/black) my dome light came on, clock was working with the door open and I heard the buzzer. Then i removed it and the next day I got a head unit i was going to put in permanently, but when i did that same thing again..nothing. I think tried the same head unit that made that stuff work before and nothing. Like i was saying to, it doesnt seem that im getting any power from the constant wire in the radio harness and the radio fuse under dash there is fine.....im not sure how to diagnose whats going on lol.

There is either a bad wire or fuse you are missing. I can look later if i have time but you need to follow the constant wire in the FSM that powers all of those items and find out where is is bad or if there is an open fuse.

Ok, i feel like a complete fool right now, but I checked all the fuses and low and behold the ROOM LAMP (or whatever its called) 10amp fuse was blown. I replaced it and on back the dome, the buzzer, the constant on radio harness works and the clock in the cluster is good. Far as the trunk light not working, I got another latch and swapped em and now it works so I guess the little ground or whatever those wires are connected to was some how busted.

Only thing now that i cant seem to figure out is why my hazard lights.
I tried another hazard button, no dice. The button illuminates with the dimmer, just doesnt do anything when i push it. Just to be sure i even swapped the hazard light fuse under the dash with a known good one. Far as the trunk light, i tested the socket/bulb work fine so Im not sure whats going on there either....any ideas?