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[Mk2] [Turbo] More stereo woes

 
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Mike




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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Fri Feb 27, 2015 10:00 pm    Post subject: [Mk2] [Turbo] More stereo woes Reply with quote Reply with quote including images

Ever since I disturbed my aerial unit I've had problems with the stereo. I have an aftermarket stereo which has been wired directly to the battery by a previous owner. I understand the aerial unit serves as the earth for the stereo and every so often the power would be lost, I'd mess around with the aerial and it would return.
Recently power to the stereo was disturbed at the battery and no amount of messing with the power or the aerial will fix it. All fuses look ok at least the ones I'm aware of. Is it possible to relocate the earth from the aerial to a different location that's more reliable? I'm a complete novice with electrics.
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Nails
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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Fri Feb 27, 2015 11:28 pm    Post subject: Reply with quote Reply with quote including images

Your aftermarket headunit should already have an earth wire on it. Just earth it.

some have a big fixing o n the back to attach one too
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madbasshunter
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1991 Toyota MR2

PostPosted: Sat Feb 28, 2015 12:24 pm    Post subject: Reply with quote Reply with quote including images

The metal brackets that fit the stereo earth it as they are bolted to the metal behind the dash and the stereo [Wink] but it wont hurt to add more as he /\ said
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RyanRs wrote:
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explain how the coolant leaves the expansion tank and goes back into the coolant system?


Seriously , you don't know the answer to this? and you call yourself a car mechanic [Shocked]
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acf8181
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1994 Toyota MR2 Mk2 NA Rev3

PostPosted: Sat Feb 28, 2015 12:36 pm    Post subject: Reply with quote Reply with quote including images

there is an earth wire from the main stereo connector....wouldnt be there if it wasn't supposed to be earthed [Wink]

also, if connected directly to your batt, it has got its own fuse in line i hope? if not, put one in.
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thomp1983
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PostPosted: Sat Feb 28, 2015 1:10 pm    Post subject: Reply with quote Reply with quote including images

Id get yourself a multimeter and spend some time refitting it properly, all the wiring with there correct fuses should be there
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madbasshunter
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1991 Toyota MR2

PostPosted: Sat Feb 28, 2015 1:28 pm    Post subject: Reply with quote Reply with quote including images

thomp1983 wrote:
Id get yourself a multimeter and spend some time refitting it properly, all the wiring with there correct fuses should be there


I think that is the best advice and would like to see pictures of this stereo and the wiring behind as you have put a few posts up on the subject now

http://www.imoc.co.uk/forums/viewtopic.php?t=176798&start=0&postdays=0&postorder=asc&highlight=

http://www.imoc.co.uk/forums/viewtopic.php?p=1539335&highlight=#1539335

The only time I have known the stereo earth through the aerial is when I have been fitting stereos in mr2's. This is when have plugged the iso loom in and the stereo is in my hand not working, I have then plugged aerial in and it works. As I have said once fitted it will then earth through the brackets.
The brown wire on the toyota loom is supposed to be earth but my tracing it on the loom shows it goes from the radio plug to the amplifiers not to the body.
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thomp1983
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PostPosted: Sat Feb 28, 2015 1:43 pm    Post subject: Reply with quote Reply with quote including images

To expand on my original post id get some iso plugs with tails and wire them in, id personally add my own known good chassis earth but i always tend to run amps so a splid proper earth is important
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acf8181
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1994 Toyota MR2 Mk2 NA Rev3

PostPosted: Sat Feb 28, 2015 6:50 pm    Post subject: Reply with quote Reply with quote including images

madbasshunter wrote:


The only time I have known the stereo earth through the aerial is when I have been fitting stereos in mr2's. This is when have plugged the iso loom in and the stereo is in my hand not working, I have then plugged aerial in and it works. As I have said once fitted it will then earth through the brackets.
The brown wire on the toyota loom is supposed to be earth but my tracing it on the loom shows it goes from the radio plug to the amplifiers not to the body.


I had a kenwood that did same....so i think its some weird headunit design

Yep, on active systems the headunit earths via the amp, same goes for the power to it [Wink]
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madbasshunter
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1991 Toyota MR2

PostPosted: Sun Mar 01, 2015 8:54 am    Post subject: Reply with quote Reply with quote including images

acf8181 wrote:
Yep, on active systems the headunit earths via the amp, same goes for the power to it [Wink]


I know I was quite surprised to learn (as I removed the loom) that the power comes in at the fusebox in drivers footwell, behind dash to the centre, then down the centre console to the amps behind the passenger seat. Then from the amps to the stereo changing wire colour as it goes [Wink] ie 12v is red from fusebox to amp

My question is about the brown earth wire, is it an earth for the amps from the stereo? not an earth for the amps and stereo. I am not getting continuity from the brown wire to the amp casings as I thought I would if the earth came from the brown wire. Problem is I can't test this properly by testing if the brown wire is earth when not plugged into a stereo as my active loom is out of the car [d'oh!]
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Pauln
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1993 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sun Mar 01, 2015 12:24 pm    Post subject: Reply with quote Reply with quote including images

Looking at the wiring diagram, this seems to show two brown wires coming off the stereo:

Wiring Diagram

One of these seems to simply act as a ground point for the screen on the audio cables, and the other seems to be the signal cable for the rear left channel. But there doesn't seem to be a dedicated wire for grounding the stereo as such, so I guess they must rely on grounding via the chassis when bolted in place.

The amps however do appear to use a brown wire for grounding to a central point, but this doesn't seem to be connected to the stereo, which does seem a bit odd.
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acf8181
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1994 Toyota MR2 Mk2 NA Rev3

PostPosted: Sun Mar 01, 2015 6:59 pm    Post subject: Reply with quote Reply with quote including images

Pauln wrote:
Looking at the wiring diagram, this seems to show two brown wires coming off the stereo:

Wiring Diagram

One of these seems to simply act as a ground point for the screen on the audio cables, and the other seems to be the signal cable for the rear left channel. But there doesn't seem to be a dedicated wire for grounding the stereo as such, so I guess they must rely on grounding via the chassis when bolted in place.

The amps however do appear to use a brown wire for grounding to a central point, but this doesn't seem to be connected to the stereo, which does seem a bit odd.


was an extra green wire in one of the screened cables on mine (the left screened cable on that diagram)....suspect that may be the earth (never tested it to know for sure though)
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Mike




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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sun Mar 01, 2015 7:48 pm    Post subject: Reply with quote Reply with quote including images

Other than the aerial there was no earth, plus the head unit was toast. Have established a new earth and bought a new head unit so it's working now.
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