[MOSFET]

Hey Guys!!! How's it hanging? Now I know an awful lot about car audio and
the nature of voltage, amperage, watts, ect.

But I don't know much about the complexity of a car's electrical system and
that is EXACTLY the problem I'm having.

The car is a 1989 Mazda MX-6, it's my wife's car, and we recently had some
problems with it stalling, missing, and even dying sometimes. So after
doing all the things I know how to do (changing air filter, fuel filter,
plugs, wires, and several other things) I took it to a "shade tree" mechanic
who lives very close to us. I should say now that she had a simple system
in her car that consited of only a Pioneer HU and some after market BA
speakers (she listens to talk radio so there was really no point in building
her a big system, even though I have a spare amp and sub just sitting
around, I had to twist her arm just to put in the Pioneer and Boston
speaks), that system worked fine up until we took it to this mechanic.

When we got the car back, we found he had needed to replace the distributor,
cap, rotor, and coil. The car ran fine once again however the weird thing
is that the Pioneer deck no longer came on. So I took the dash apart and
started checking things with my multimeter (oh, I should say that the VERY
FIRST thing I did was check all the fuses which were fine). The B+ voltage
was fine, as was the ground. But the red ignition wire was reading .64
volts when the car was on OR OFF. So I said to myself, fine, I'll find
another 12 volt source that turns off when the key is turned off. I checked
the ciggarette lighter wire and every other wire I could find.

No dice. Although the yellow B+ wire seems to be fine, the ignition wire
(or any other wire that should produce 12 volts when the key is turned) is
only producing .64 volts whether the key is turned or not.

Help!!!! I've never come accross this type of problem before. Obviously it
has something to do with the car's ignition system (I think) but I have no
idea where to look for the fault. Like I said, the car runs great. Also,
again the radio had worked fine in the past using the red ignition wire as
my "turn-on" wire. Now only the yellow B+ wire is the only wire I can find
in that cavity that produces 12 volts, and of course it produces those 12
volts whether the key is turned on or not.

I really need some help here. Maybe even a work around as the car appears
to run just fine yet something is clearly wrong but does not seem to be
effecting the performance of the car.

Thank you in advance,

MOSFET

[Mister.Lull]

Yikes...

I can't offer too much in the way of advice here. I know you said you
checked the fuses, but if you only checked the fuses you thought to be
relevant to the stereo, I would suggest checking ALL of them
(especially the ones in the engine bay). I would suspect (as you do)
a larger issue.

Beyond that, I can only offer workarounds. For example, installing a
toggle switch in a discreet location (like a 2nd "on/off" switch) for
the head unit, and basically running it off of the same constant power
wire that the deck is already using.

Hopefully someone has some better answers for you, but if not, I live
in your neck of the woods and I'd be happy to install such a switch
for you!

~Mister.Lull

On Mar 12, 7:29*pm, "MOSFET" wrote:
Hey Guys!!! *How's it hanging? *Now I know an awful lot about car audio and
the nature of voltage, amperage, watts, ect.

But I don't know much about the complexity of a car's electrical system and
that is EXACTLY the problem I'm having.

The car is a 1989 Mazda MX-6, it's my wife's car, and we recently had some
problems with it stalling, missing, and even dying sometimes. *So after
doing all the things I know how to do (changing air filter, fuel filter,
plugs, wires, and several other things) I took it to a "shade tree" mechanic
who lives very close to us. *I should say now that she had a simple system
in her car that consited of only a Pioneer HU and some after market BA
speakers (she listens to talk radio so there was really no point in building
her a big system, even though I have a spare amp and sub just sitting
around, I had to twist her arm just to put in the Pioneer and Boston
speaks), that system worked fine up until we took it to this mechanic.

When we got the car back, we found he had needed to replace the distributor,
cap, rotor, and coil. *The car ran fine once again however the weird thing
is that the Pioneer deck no longer came on. *So I took the dash apart and
started checking things with my multimeter (oh, I should say that the VERY
FIRST thing I did was check all the fuses which were fine). *The B+ voltage
was fine, as was the ground. *But the red ignition wire was reading .64
volts when the car was on OR OFF. *So I said to myself, fine, I'll find
another 12 volt source that turns off when the key is turned off. *I checked
the ciggarette lighter wire and every other wire I could find.

No dice. *Although the yellow B+ wire seems to be fine, the ignition wire
(or any other wire that should produce 12 volts when the key is turned) is
only producing .64 volts whether the key is turned or not.

Help!!!! *I've never come accross this type of problem before. *Obviously it
has something to do with the car's ignition system (I think) but I have no
idea where to look for the fault. *Like I said, the car runs great. *Also,
again the radio had worked fine in the past using the red ignition wire as
my "turn-on" wire. *Now only the yellow B+ wire is the only wire I can find
in that cavity that produces 12 volts, and of course it produces those 12
volts whether the key is turned on or not.

I really need some help here. *Maybe even a work around as the car appears
to run just fine yet something is clearly wrong but does not seem to be
effecting the performance of the car.

Thank you in advance,

MOSFET

[MOSFET]

Beyond that, I can only offer workarounds. For example, installing a
toggle switch in a discreet location (like a 2nd "on/off" switch) for
the head unit, and basically running it off of the same constant power
wire that the deck is already using.

Thanks Lull, in fact that is EXACTLY what I am doing for now. I cut the red
ignition wire, twisted the yellow B+ and deck's ignition wire together and
so the radio works fine, you just have to remember to turn it on and most
importantly, OFF again when you are done. Like I said, I cut the red
ignition wire (and crimped the ends) so no current can flow back from the B+
into the ignition system.

But as you apptly put it, I have a larger issue I need to resolve as most of
my dash lights currently don't work (and they did before), cigarrette
lighter does not get any power, ect. I know all these problems are related
in some way.

I did check ALL the fuses in the fuse box in the cabin. Are you saying (and
please excuse my ignorance, I really don't know much about car electronics)
that there is another bank of fuses under the hood? If so, one of those
could be blown and be the source of my power problems.

It's strange. You would think that if the ignition wire was sitting at only
..64 volts there might be engine problems still, but there is not. It runs
great.

This one really has me baffled. Again, thanks for the reply, Lull. Talk to
you later...

Nick

[James]

Nick, exactly how did you check your fuses?

did you just LOOK at them, or did you use an ohm meter ?

I had an experience in another group when a user could not get his head unit
to come on, no matter what. He had checked and double checked all fuses,
and found nothing wrong. I suggested that he remove the relevant fuse and
actually put an ohm meter to it. Sure enough, it was bad, although he swore
it looked perfect. They can burn out right close to the base, where you
can't see the defect.

In addition to fuses, have you looked for and checked all circuit breakers ?

I do agree that your symptoms are rather weird, but just thought I would go
back to one of the basics....

good luck , and keep up posted !!

James

[MOSFET]

James,

Please tell me how two set my multimeter (it's a pretty expensive type) to
check the ohms of my fuses? I think you may be on to something as I've
checked everything else.

Do I set the multimeter to a certain ohm value (it has 200 ohms - 2000k and
three values in the middle, 200k, 20k, 2000 and then 200). Which setting
should I use? And then do I simply touch the two probes on each blade?
What value SHOULD I see? I'm sorry but I have never checked ohm values
before except when I'm not sure about a speakers ohm value, and yes, I know
that is not an accurate way to judge the ohm value of a speaker as the value
flucuates with frequencies, but it does give you a ballpark.

Any assistance in this area would be appreciated. I know ohms measure
electrical resistance butI do not know the correct procedure for checking
fuses.

Thank you in advance,

Nick
"James" no wrote in message
.. .
Nick, exactly how did you check your fuses?

did you just LOOK at them, or did you use an ohm meter ?

I had an experience in another group when a user could not get his head
unit to come on, no matter what. He had checked and double checked all
fuses, and found nothing wrong. I suggested that he remove the relevant
fuse and actually put an ohm meter to it. Sure enough, it was bad,
although he swore it looked perfect. They can burn out right close to the
base, where you can't see the defect.

In addition to fuses, have you looked for and checked all circuit breakers
?

I do agree that your symptoms are rather weird, but just thought I would
go back to one of the basics....

good luck , and keep up posted !!

James

[James]

I would set it to 200 ohms, and then hold the two leads together, and adjust
the meter needle (zero adjustment) so that the meter reads full value, or
full continuity.

Whcn checking the fuse, you are not looking for a specific ohm value. You
are just looking for circuit continuity. So, you adjust your meter first,
by holding the two leads together, and adjusting your meter, and then do the
same with the two blades of the fuse, and if the fuse is good, you should
get full continuity. Either you do or you don't, and that will tell you if
the fuse is bad (open) or good (full continuity).

Stated differently, a bad fuse will show no reading (open), and a good fuse
will show continuity (full meter reading).

James

[MOSFET]

I just now got my multimeter out and set it to 200 ohms. When the probes
are not touching I get no reading at all. When the probes touch each other
OR touch each blade of a blade fuse I get a .5 ohm reading. I just now went
out to my car and tested every fuse, they all seemed fine as I got the .5
ohm reading.

So it does not appear that I have a bad fuse as now I have electricaly
tested them as well as visually tested them.

Man, this one really has me stumped. Again, the engine starts and runs
perfectly. Yet obviously something is seriously wrong with my electrical
system as about half of the dash lights do not work (fortunately all the
intrument cluster lights do work). But the instrument cluster lights are
about the only lights that DO work. The ciggarrette light does not work
(nor do I get power to the cigarette lighter), the heater lights don't work
and the shifting lights do not work. Yet all of these had worked before.

Also, the battery and alternator appear to be fine as I just checked that.
I was getting 14.4 from the battery.

HELP!!!

Nick

[MOSFET]

My check engine light winks at me now and then, but never stays on more than
5 seconds or so. The car had just been tuned up and as I said before, it
runs perfectly (no missing, no loss of power, on stalling, no trouble
starting, and it idles very, very smoothly for a four banger).

I have to think that the check engine light MUST be related to this
electrical/voltage problem somehow as every other mechanical system checks
out fine.

Part of my wants to take it to a reputable automotive repair service and
have them diagnois the problem. But another part of me figures that as long
as it is running well and I can do work-arounds to get the stereo working,
why spend the money? Especially in light of the fact I have just paid this
other mechanic $500 to replace the distributor, cap, rotor, coil and give it
a full tune-up.

The problem is, I discovered through working with him he is kind of a jerk
and there is no sort of gaurentee. So if I take it back to him, it's not
likely (in fact I'm sure it's not likely) that he will give me any kind of
discount to help discover the problem with the ignition voltage. I think I
will just keep trying different things and doing more research (I need to
buy a Haines manual) and see if I can stumble onto the problem. I actually
enjoy this kind of car-detective work.

But after a two or three more weeks of this, if I have not found the problem
I will take it into my old tried and trusted car-repair shop.

You see, my BIG concern revolves around the fact that if this particular
electrical system is not working correctly, might it effect others down the
road? I don't want to have to find out the hard way.

Again, IF ANYONE HAS ANY SUGGESTIONS, I AM ALL EARS AND WILL CERTAINLY TRY
IT IF I CAN.

Thanks,

Nick