oem head unit problem

[Nick]

hey all, i was driving along and hit a mild bump and my head unit shut off. the lights for all the buttons still have power so i guess that's a separate circuit. the head unit doesn't power on and the screen doesn't illuminate or anything. i've checked the fuses under the hood and found an "audio" fuse, tested it's resistance and it's fine.

something interesting that i can't figure out is when i pressed the eject button it ejected the cd and i can hear the motor still working when i press it every time. is the eject button on a different circuit than the on/off button? anyone have this problem before? i have a loc installed, checked all the wire splices and connections into the plugs and they're solid. i have the unit out right now and gonna search for a fuse in there but after that i'm out of ideas. any idea? thanks

[sas]

Second fuse is the ROOM fuse.
Or you can measure the voltage on the connector.
It’s all what you need to switch on the radio.
Terminal B - +12V ROOM fuse.
Terminal R - +12V from Radio fuse.
Terminal W – Ground
http://miata.fosketts.net/index.php?title=J-01

[Nick]

great info! i made it more complicated that it was, blown fuse in the cabin. you sure know your stuff! thanks again

[Nick]

so i after replacing the 7.5 "radio" fuse it blew a few days later. i'm sure if i put another one in it'll go. anyone know the reasons for a fuse constantly blowing? if i gotta check for a short to ground following the wire would be a real pita. are there any other possibilites?

[Noisy Crow]

so i after replacing the 7.5 "radio" fuse it blew a few days later. i'm sure if i put another one in it'll go. anyone know the reasons for a fuse constantly blowing? if i gotta check for a short to ground following the wire would be a real pita. are there any other possibilites?

Pretty much... no. Tracing the wire shouldn't be too difficult though... it runs right from the head unit to the PJB. Yellow wire from the head unit to pin AA on connector J03 on the PJB, which is under the glove box. Odds are the problem is a pinched wire behind the head unit; it will be taped up as part of the harness everywhere else.

Assuming you haven't tapped into that wire for something else... in which case I would look at the add-on first.

[Noisy Crow]

Pretty much... no. Tracing the wire shouldn't be too difficult though... it runs right from the head unit to the PJB. Yellow wire from the head unit to pin AA on connector J03 on the PJB, which is under the glove box. Odds are the problem is a pinched wire behind the head unit; it will be taped up as part of the harness everywhere else.

Assuming you haven't tapped into that wire for something else... in which case I would look at the add-on first.


Oh... there are two power feeds to the head unit, one switched, one not. The switched feed runs through the 7.5A fuse.

[Nick]

will look for that pinched wire, thanks for that extra bit of info on your 2nd post

[sas]

I was so busy last week that even hadn’t a time to answer. I’m bit confused, what the audio set you have. The existing audio fuse means that you have the Bose amplifier in the same time you wrote you have a LOC.
I don’t have the wiring from head unit and the all what I think is just a supposition.
Main power for head unit is coming from Room fuse. The Radio fuse is powering small controllers inside of the head unit. If you have problem with head unit, it is an internal shorting, or maybe it’s a shorting of the remote power wire (if you have the Bose) .
As for harness, J03 connector it’s the wide blue connector on the upper side of the PJB.
From pin AA the yellow wire is running to the head unit, somewhere this wire is split. This “Radio” wire also feeds the information display(yellow wire), and, if you have the Navi, Navi display(yellow/blue wire) and Navi controller(yellow/black wire). There is plastic everywhere,look places where harness contacts with metal or damaged. Possibly, you have an attached wire for remote power or for LOC and this wire being short to chassis . Also, look the harness from information display, sometimes it rubs the edge of the head unit.
You could solder the bulb 35-55W to the old fuse , insert this fuse with soldered bulb instead radio fuse, switch on the ignition ,move the harness and look if bulb is flashing somewhere.

[Noisy Crow]

you wrote you have a LOC.

Thinking about his problem.... I think you probably hav pointed out the source of the problem. LOC implies external amp. How is the external amp swtiched on /off? Usually from switched feed to the head unit... which is the fuse that is blowing... if so, odds are high the wire from to the amp wasn't protected properly and is grounding out.

[Nick]

right on, just had time to tackle it last night and the electrical tape had come off of my splice. i had spliced the yellow AA wire with the remote wire from the amp. since i love my music i went through a bunch of fuses for the temporary fix, but i wrapped it up real good now. thanks for your help guys =]

[TheMAN]

wrapping it "real good" isn't a real fix
you need to solder and heat shrink the wires if you don't want this to happen again

[Noisy Crow]

Glad you got the prolem fixed! :)


wrapping it "real good" isn't a real fix
you need to solder and heat shrink the wires if you don't want this to happen again

Yeh. Even a 3M vampire tap would be better than just wrapping and taping, as we aren't talking a lot of current here. At the very least... once the splice has been taped up put a tie wrap over the tape to keep it from unwinding.

Another good option are these guys:
http://www.posi-lock.com/posiplug.html

[booki]

Hi,
this is my first time in forum,

i have Mazda3 2005 Sadan,

i've disassembled the head unit and disconnected the Ant connector, i opend the switch and the HU didn't want to turn on , and now it not works any more,

i checked the the battery+12v and the switched 12v in the J-01 connector and it has both powers,

the only thing i can think about is that something is burned inside the HU, i don't have experience with Mazda so i hope there is a solution that i don't know about,

i'm looking forward for any idea,
thanks.

[booki]

the problem is fixed it was the front panel connectors to PCB moved out,

thanks.

[crystal8484]

my girlfriend at work has this problem right now, her LCD screen is completely blank, won't even light up but all other lights on the dash work. Mazda is telling her she probably has to replace the entire screen (without even having looked at the car)

Any ideas on what I can tell her to say when she goes to the dealership to get it officially checked out so they don't steal all her money???

I've said so far it could be the connector to the HU, but she doesn't know how to access that on her own of course.

[Noisy Crow]

Does the head unit work at all? If it does and the LCD isn't working, then, yes, the whole thing probably needs to be replaced.

[crystal8484]

Does the head unit work at all? If it does and the LCD isn't working, then, yes, the whole thing probably needs to be replaced.

Damn, sounds like that may be the case. It's completely blank, although radio/CD's are still working she just can't see any info/radio stations etc.

[S.F.W.]

Damn, sounds like that may be the case. It's completely blank, although radio/CD's are still working she just can't see any info/radio stations etc.

if the whole thing needs to be replaced, look used.

[crystal8484]

Ha, well here is an update.

Friend goes to the dealership. They immediately say they have to order a part, without again, having even looked at it. My friends Dad tells them to hold the eff up and keep it in their pants for a second. They all agree to just inspect the HU.

Service manager comes back 20 minutes later. "We need to order a part!!" They inquire how much it will be...."$500 something dollars" BOTH of their faces drop to the ground. Some negotiating goes around, dealer suggests to buy used off kijiji as an example. But oh, what's this... a mechanic comes in and says he finds a USED screen and the dealer now says, "Oh! we will just charge you for labour, you can have the part for free!"

SO, from saying it would be $500 + labour, to buy used on kijiji, to miraculously finding a used part randomly in the parts department to getting it for free seems like the dealership trying to make themselves seem like saviours.

However, she has a working LCD screen, that's all that really matters in the end I suppose.

[Thrizzl3]

Ha, well here is an update.

Friend goes to the dealership. They immediately say they have to order a part, without again, having even looked at it. My friends Dad tells them to hold the eff up and keep it in their pants for a second. They all agree to just inspect the HU.

Service manager comes back 20 minutes later. "We need to order a part!!" They inquire how much it will be...."$500 something dollars" BOTH of their faces drop to the ground. Some negotiating goes around, dealer suggests to buy used off kijiji as an example. But oh, what's this... a mechanic comes in and says he finds a USED screen and the dealer now says, "Oh! we will just charge you for labour, you can have the part for free!"

SO, from saying it would be $500 + labour, to buy used on kijiji, to miraculously finding a used part randomly in the parts department to getting it for free seems like the dealership trying to make themselves seem like saviours.

However, she has a working LCD screen, that's all that really matters in the end I suppose.

im glad that it worked out for her. But honestly $500 for a HU?:loco

[stealthman12]

i just ran into the same problem as Crystal's friend today.
Radio, CD's, CD Changer work but there is no display on the LCD screen.
It was working perfectly fine yesterday and this morning when i went to start it up it didn't light up. All the lights work.
On a side note, there was some electrical buzzing last night and this morning when i shut the car off but i couldn't pin point where it was coming from.
I also have my HIDs tapped into a wire in the fusebox to keep them as my DRL's, if that makes a difference.
Any suggestions?
Do I possibly need a new head unit or just the screen?

[TheMAN]

hopefully the used MID LCD is not the one that had a fast running clock (06 models)

crappy dealers FTL