HU wont turn on. Ideas?

[mokedaddy 5,000+ posts]

wait -12v with car turn on? wth......

That just means the leads were reversed. No harm done.

 

[Supergumby5000 5,000+ posts]

Which wires are you testing and which got which results?

okay, DMM + on the battery constant wire, and DMM - on the ground, i got .04 volts (nothing)

DMM + on the battery contstant wire, and DMM - on the ignition wire (red), i get -12.6 volts

with the car totally on (not on accessory), i get the same results, accept with the ignition wire, it reads -14v instead of -12.6

 

[thaster 10+ year member]

okay, DMM + on the battery constant wire, and DMM - on the ground, i got .04 volts (nothing)
DMM + on the battery contstant wire, and DMM - on the ignition wire (red), i get -12.6 volts

with the car totally on (not on accessory), i get the same results, accept with the ignition wire, it reads -14v instead of -12.6

sound like there's something wrong with your battery constant/yellow wire. is that yellow wire fused btw? also i think you suppose to ground the wire not probe it to the ignition wire.

 

[mokedaddy 5,000+ posts]

okay, DMM + on the battery constant wire, and DMM - on the ground, i got .04 volts (nothing)
DMM + on the battery contstant wire, and DMM - on the ignition wire (red), i get -12.6 volts

with the car totally on (not on accessory), i get the same results, accept with the ignition wire, it reads -14v instead of -12.6

Yeah you dont ground the lead to the accessory wire. That is why its reading negative volts. Your constant wire has a blown fuse. That is usually underneath the hood but not always.

Do the continuity test on both sides of all the fuses. underhood first than inside if you dont find one that is blown.

What kind of car is it?

 

[Supergumby5000 5,000+ posts]

Yeah you dont ground the lead to the accessory wire. That is why its reading negative volts. Your constant wire has a blown fuse. That is usually underneath the hood but not always.
Do the continuity test on both sides of all the fuses. underhood first than inside if you dont find one that is blown.

What kind of car is it?

Grounding out to frame with the DMM -, i get 14volts on the ignition wire and nothing on the constant wire, so as you said its a bad fuse on the constant wire?

I check the radio fuse under the dash with continuity test and it read fine. Im not sure what fuse to look for underneath the hood though, none of their names ressembled anything to do with the radio...

 

[Supergumby5000 5,000+ posts]

oh, and a 2000 ford escort ZX2

 

[mokedaddy 5,000+ posts]

Grounding out to frame with the DMM -, i get 14volts on the ignition wire and nothing on the constant wire, so as you said its a bad fuse on the constant wire?
I check the radio fuse under the dash with continuity test and it read fine. Im not sure what fuse to look for underneath the hood though, none of their names ressembled anything to do with the radio...

Yes bad constant fuse. I am not sure what it is going to be under either so just test them all until you find it. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Its not hard nor does it really take long.

 

[thaster 10+ year member]

just look if the fuse is bad. you dont really have to test them with a DMM. the middle of the fuse shouldnt be connected if it were bad. Also maybe you could tap into another constant 12v wire in your car.

 

[mokedaddy 5,000+ posts]

just look if the fuse is bad. you dont really have to test them with a DMM. the middle of the fuse shouldnt be connected if it were bad. Also maybe you could tap into another constant 12v wire in your car.

Often times you cant see the insides when they are in the fuse box. You can pull them and look but if your car is on thats a good way to throw a CE light. Its not hard to test and do it right so why wouldnt you?

 

[Supergumby5000 5,000+ posts]

found it! it was a fuse titled as "room". Easy find eh?

Thanks for the input everyone