My 12v constant power is broken :(

[beer]

Per my other thread, I'm having some problems getting in a new head unit. My old one was severely jacked up from a thief, and I managed to remove it by essentially tearing it apart, which was fine since I didn't have the faceplate (it was stolen).

Anyways, I was putting in my new one and soldered my wires. I was testing the power supply and I have a 14v drop from my 12v switched to ground, but I'm not getting more than 50 mV across my 12v constant to ground.

I checked all my fuses using a continuity tester on my multimeter and they all appeared to be fine. If it isn't a fuse, what else could it be?

Not that it should matter, but it's a 98 ford contour. This is more of a general electrical system issue than ford specific

 

[Shockwave]

The 12v constant may only act as a trickle power supply. Maybe 50milliamps is correct, since the device may pull power from the 12v switched.

 

[Pepsi90919]

any difference when you turn on acc/ignition ?

 

[beer]

Well, it's not 50 mA, I'm getting 50 millivolts (mV). Where I should be getting 12. Even if there was no current draw I still should have a potential difference.

On or off I don't notice a difference. And my new head unit doesn't operate when I plug it in, and the 12v switched works, so I can only assume that this 12v constant is what's causing it to not work.

 

[Pepsi90919]

it just looks for 12v on the switched inputs as a reference to draw from the constant supply. i suppose, if you want, you could rig up a diode in there somehow to branch off one of the switched inputs, but you'd lose your presets and everything every time you turned off the car.

 

[Pepsi90919]

and which side of the fuses did you check for continuity? i hope it wasn't the supply side. i would pull some out and physically inspect.

 

[Heisenberg]

Are you sure all the fuses are good? Both the in-dash and underhood ones?

 

[Shockwave]

Originally posted by: Heisenberg
Are you sure all the fuses are good? Both the in-dash and underhood ones?

That screwed me once. Forgot the check the under hood ones.... Man was that a long day

 

[beer]

I have in-dash fuses I just checked under the hood.

Crap. I don't even know about the in-dash ones....

too bad I dont have my manual still

 

[beer]

pepsi -

I pulled them out and tested the continuity through the fuse itself.

 

[beer]

OK

So I got a Haynes manual and checked all the fuses that it could be.
I physically pulled out the fuses and ran them through a continuity tester and they all are intact.

I'm still only getting a fraction of a volt on my 12v constant line.

If shockwave says is correct, that it is a trickle power supply, it should still remain at 12-14V, trickle doesn't mean it's variable voltage, only variable cufrrent, rhight????

 

[Fiveohhh]

follow the lines back and see where it drops off.

 

[Dufman]

Why not just run new wires to the fuse box?

 

[Spencer278]

Just run a new wire from the battery to your CD player and it will be fixed.

I would guess that something got shorted out when your Cd player was ripped out of the dash and what ever it was saved fuse from burning up.

 

[Fiveohhh]

Originally posted by: Spencer278
Just run a new wire from the battery to your CD player and it will be fixed.

If your gonna do that don't forget to fuse it.

 

[beer]

it seems like an awful lot of work to run a new wire
i don't know enough about my system to run the wire cleanly
seems like it'd be a pain in the ass to run it from the battery

 

[Fiveohhh]

Originally posted by: beer
it seems like an awful lot of work to run a new wire
i don't know enough about my system to run the wire cleanly
seems like it'd be a pain in the ass to run it from the battery

were you getting 12v at any of the fuses you tested?

 

[beer]

Originally posted by: Fiveohhh

Originally posted by: beer
it seems like an awful lot of work to run a new wire
i don't know enough about my system to run the wire cleanly
seems like it'd be a pain in the ass to run it from the battery

were you getting 12v at any of the fuses you tested?

hm...I didn't check that...I just checked the continuity of the fuses
I'll check it and let you know in a bit...

 

[lightpants]

Since I like your user name:

diagram

looks like fuse 34 and fuse 32 in the Central junction box provide the power to your radio.
check the socket where the fuse plugs in- sometimes when people install electrical devices and need a power source. It is easy to just shim in a connector where the blade of a fuse plugs in. It works, however, if you take the extra shim out, then the socket has been bent wider and doesn't make contact with the fuse blade. This can cause your problem.
check if there is power at the fuse sockett and if there is then,
Try twisting the blades of your fuse 15 degrees this will make it fit tighter and make better contact in the socket.


Jim

 

[Shawn]

Originally posted by: Spencer278
Just run a new wire from the battery to your CD player and it will be fixed.

I would guess that something got shorted out when your Cd player was ripped out of the dash and what ever it was saved fuse from burning up.

Happened to me before. A fuse was only half gone and still allowed some current to go through. Caused quite a few problems.

beer, your fuses are usually under the dash on the driver side or somewhere around there if you have them.

 

[beer]

Originally posted by: iloveme2

Originally posted by: Spencer278
Just run a new wire from the battery to your CD player and it will be fixed.

I would guess that something got shorted out when your Cd player was ripped out of the dash and what ever it was saved fuse from burning up.

Happened to me before. A fuse was only half gone and still allowed some current to go through. Caused quite a few problems.

beer, your fuses are usually under the dash on the driver side or somewhere around there if you have them.

Yeah i found them. I haven't dealt with this issue before and jest knew of the fuses under the hood, not under the driver's side seat. I'm a total car n00b, obviously.

I'm going to check fuse 34. I checked 32 last night and it was intact. I'll be back in 10 min

 

[beer]

lightpants -

It was fuse 34. I replaced it, I got 12V across the constant, the stereo worked and everything is beautiful. If you weren't 1300 miles away I'd buy you a case of your fav brew

You may ask, why didn't I check that last night?
I didn't buy the haynes manual until 7:30 or so, and when I came back I couldn't find the primary fuse box. I found it at around 8, but at that time it was dark, so I just checked the most obvious fuse (34) and since that was intact, I delegrated the rest of the stuff for today.

I got back from class at noon and took your advice and looked at F32. It worked beautifully. You may ask, why didn't I realize the interior lights weren't working (which is what F34 controls)? It's because the sensor on the driver's side door doesn't work, so the car never knows when the door opens/closes...so I had gotten used to never seeing the interior lights on when I opened the door

many beers to you

 

[woowoo]

Is the door switch getting 12v?
(Don't stop now.....)

 

[beer]

Originally posted by: woowoo
Is the door switch getting 12v?
(Don't stop now.....)

The interior lights work for the other 3 doors and when they open and close. Just not the driver's side (this is, of course, when I haven't blown the fuse which I only blew two days ago). I had it fixed once under warranty and they said they had to remove the door panel to solve it, so it isn't that big of a deal to me - I just need to remember to turn off my lights because it doesn't beep if I don't (since it doesn't know the door's ajar)