Weird electrical issue...

....with my wipers and fan. Not the engine's fan, but the fan for the
cabin air.

I took a long trip in my 90A from Vancouver to Edmonton and then home
again (I'm actually writing this from my last stop in the Okanagan) with
my GF.

And somewhere along the line in Banff/Jasper national parks, my wipers
would stop working at the same time (as I soon discovered) as the fan
for the internal ventilation system would fail. But then they would
start working again; almost always (but not 100%) correlated with
stopping and then restarting the engine.

Now, check me on this: according to the manual, the wiper and the
ventilation fan are on different circuits, right?

So does anyone know where I should start looking for the fault? Because
I don't get it.

--
Alan Baker
Vancouver, British Columbia
<http://gallery.me.com/alangbaker/100008/DSCF0162/web.jpg>

On 6/9/2010 1:25 PM, Alan Baker wrote:
> ...with my wipers and fan. Not the engine's fan, but the fan for the
> cabin air.
>
> I took a long trip in my 90A from Vancouver to Edmonton and then home
> again (I'm actually writing this from my last stop in the Okanagan) with
> my GF.
>
> And somewhere along the line in Banff/Jasper national parks, my wipers
> would stop working at the same time (as I soon discovered) as the fan
> for the internal ventilation system would fail. But then they would
> start working again; almost always (but not 100%) correlated with
> stopping and then restarting the engine.
>
> Now, check me on this: according to the manual, the wiper and the
> ventilation fan are on different circuits, right?
>
> So does anyone know where I should start looking for the fault? Because
> I don't get it.
>

No idea about your problem -- long-distance troubleshooting of electrical
problems is difficult at best. (loose connection comes to mind though)

But while you are there make, sure to get some of the local wine which
might help you forget the problem... ;-)

On Wed, 09 Jun 2010 10:25:21 -0700, Alan Baker >
wrote:

>...with my wipers and fan. Not the engine's fan, but the fan for the
>cabin air.
>
>I took a long trip in my 90A from Vancouver to Edmonton and then home
>again (I'm actually writing this from my last stop in the Okanagan) with
>my GF.
>
>And somewhere along the line in Banff/Jasper national parks, my wipers
>would stop working at the same time (as I soon discovered) as the fan
>for the internal ventilation system would fail. But then they would
>start working again; almost always (but not 100%) correlated with
>stopping and then restarting the engine.
>
>Now, check me on this: according to the manual, the wiper and the
>ventilation fan are on different circuits, right?
>
>So does anyone know where I should start looking for the fault? Because
>I don't get it.
I am not familiar with this particular electrical system, but problems
described as "weird" are usually related to bad grounds. Separate
circuits (ie, separate fuses, separate switches, etc) often rely on
one good path to ground for the return of the circuit. If that ground
is bad due to corrosion of a loose ground strap, all sorts of strange
things can happen. Usually things like having the turn signals stop
whenever the brakes are applied etc happen, but it is possible your
symptom is caused by a loose ground somewhere.

On 10/06/2010 5:25 a.m., Alan Baker wrote:
> ...with my wipers and fan. Not the engine's fan, but the fan for the
> cabin air.
>
> I took a long trip in my 90A from Vancouver to Edmonton and then home
> again (I'm actually writing this from my last stop in the Okanagan) with
> my GF.
>
> And somewhere along the line in Banff/Jasper national parks, my wipers
> would stop working at the same time (as I soon discovered) as the fan
> for the internal ventilation system would fail. But then they would
> start working again; almost always (but not 100%) correlated with
> stopping and then restarting the engine.
>
> Now, check me on this: according to the manual, the wiper and the
> ventilation fan are on different circuits, right?
>
> So does anyone know where I should start looking for the fault? Because
> I don't get it.
>
For the NB (not sure about NA, but probably the same) the electrical
diagram shows that the air-con blower fan / rear defogger(if fitted),
wipers, and electric windows (if fitted) share a common circuit from the
main ignition switch (black/red striped wire from ignition switch on NB)
before the fusebox. I'd be starting a search there - especially as
you've observed that it's intermittent depending on stopping and
restarting. Likely to be either a dead ignition switch, or trace the
appropriate wire from ignition switch back though to fusebox for loose
connection / damaged wire.

On 10/06/2010 9:47 a.m., Me wrote:
> On 10/06/2010 5:25 a.m., Alan Baker wrote:
>> ...with my wipers and fan. Not the engine's fan, but the fan for the
>> cabin air.
>>
>> I took a long trip in my 90A from Vancouver to Edmonton and then home
>> again (I'm actually writing this from my last stop in the Okanagan) with
>> my GF.
>>
>> And somewhere along the line in Banff/Jasper national parks, my wipers
>> would stop working at the same time (as I soon discovered) as the fan
>> for the internal ventilation system would fail. But then they would
>> start working again; almost always (but not 100%) correlated with
>> stopping and then restarting the engine.
>>
>> Now, check me on this: according to the manual, the wiper and the
>> ventilation fan are on different circuits, right?
>>
>> So does anyone know where I should start looking for the fault? Because
>> I don't get it.
>>
> For the NB (not sure about NA, but probably the same) the electrical
> diagram shows that the air-con blower fan / rear defogger(if fitted),
> wipers, and electric windows (if fitted) share a common circuit from the
> main ignition switch (black/red striped wire from ignition switch on NB)
> before the fusebox. I'd be starting a search there - especially as
> you've observed that it's intermittent depending on stopping and
> restarting. Likely to be either a dead ignition switch, or trace the
> appropriate wire from ignition switch back though to fusebox for loose
> connection / damaged wire.

Clarifying the wire colour from the ignition switch to the interior
fusebox, it should or could be black with a red stripe - not the one
that's red with a black stripe.

In article >,
wrote:

> I am not familiar with this particular electrical system, but problems
> described as "weird" are usually related to bad grounds.

I agree. There are annotated photos at miata.net identifying the
underhood ground points. They vary somewhat by year; I don't know if
Canadian Miatas differ from U.S. models, but the pictures should get you
started, anyway. Disassemble and clean each contact surface until shiny
with emery cloth or a typewriter eraser (can you still buy those?).

--
Lanny Chambers
St. Louis, MO
'94C

On 10/06/2010 12:23 p.m., Lanny Chambers wrote:
> In >,
> wrote:
>
>> I am not familiar with this particular electrical system, but problems
>> described as "weird" are usually related to bad grounds.
>
> I agree. There are annotated photos at miata.net identifying the
> underhood ground points. They vary somewhat by year; I don't know if
> Canadian Miatas differ from U.S. models, but the pictures should get you
> started, anyway. Disassemble and clean each contact surface until shiny
> with emery cloth or a typewriter eraser (can you still buy those?).
>
Except this problem isn't weird, as the circuit for wipers and heater/ac
fan is shared at the ignition switch, as per my other posts.

> > I agree. There are annotated photos at miata.net identifying the
> > underhood ground points. They vary somewhat by year; I don't know if
> > Canadian Miatas differ from U.S. models, but the pictures should get you
> > started, anyway. Disassemble and clean each contact surface until shiny
> > with emery cloth or a typewriter eraser (can you still buy those?).

I've had very good luck using 800-1000 grit sandpaper for cleaning up
ring connectors, and you can polish up a male spade with that as well.
It's less harsh that emery cloth in my opinion, that tends to remove a
bit too much material for my liking.

> Except this problem isn't weird, as the circuit for wipers and heater/ac
> fan is shared at the ignition switch, as per my other posts.

Which makes me wonder if the OP could jiggle the ignition key next
time this happens..and if that rectifies the issue right away I'd go
for a new ignition switch. And I wouldn't put it off either, as this
could be a fire hazard if that circuit has high resistance due to a
worn wiper in the moving parts of the ignition switch.

Chris

On 10/06/2010 3:08 p.m., Hal wrote:
>>> I agree. There are annotated photos at miata.net identifying the
>>> underhood ground points. They vary somewhat by year; I don't know if
>>> Canadian Miatas differ from U.S. models, but the pictures should get you
>>> started, anyway. Disassemble and clean each contact surface until shiny
>>> with emery cloth or a typewriter eraser (can you still buy those?).
>
> I've had very good luck using 800-1000 grit sandpaper for cleaning up
> ring connectors, and you can polish up a male spade with that as well.
> It's less harsh that emery cloth in my opinion, that tends to remove a
> bit too much material for my liking.
>
>> Except this problem isn't weird, as the circuit for wipers and heater/ac
>> fan is shared at the ignition switch, as per my other posts.
>
> Which makes me wonder if the OP could jiggle the ignition key next
> time this happens..and if that rectifies the issue right away I'd go
> for a new ignition switch. And I wouldn't put it off either, as this
> could be a fire hazard if that circuit has high resistance due to a
> worn wiper in the moving parts of the ignition switch.
>
We drove a 72 VW bus from LA to Quebec to Key West and back to LA.
It had a dodgy ignition switch - often needing a wiggle to get it to work.
Detoured through Death Valley on the way back - where in the middle of
nowhere, suddenly masses of smoke, sparks, and heat erupted out of the
steering column, and the bus stopped dead. A local cop stopped to check
if we were okay while I was working on it - sorting out a mass of melted
burned plastic. We had plenty of water and food with us, and he offered
to come back to check at regular intervals on his beat.
I don't think in that case it was the switch itself that
overheated/shorted out, but the constant wiggling and loosening contacts
at the back of the switch resulted in a short - perhaps eventually
wearing through insulation. A bit hard to tell from post mortem.

I'm not sure if general longevity of contacts in the ignition switch
might be related to whether there's a load on the circuit when you
switch it on and off, so that repeated slight arcing wears down the
contacts. I try to remember to switch fans, wipers, radio etc off
before I shut it down. My wife doesn't - especially the CD player left
LOUD - and that has the beautiful characteristic of a few seconds delay
while the disk initialises in the player, then some very nasty shock -
sometimes she listens to Rammstein in the car.

On Jun 9, 2:47*pm, Me > wrote:
> On 10/06/2010 5:25 a.m., Alan Baker wrote:
>
>
>
> > ...with my wipers and fan. Not the engine's fan, but the fan for the
> > cabin air.
>
> > I took a long trip in my 90A from Vancouver to Edmonton and then home
> > again (I'm actually writing this from my last stop in the Okanagan) with
> > my GF.
>
> > And somewhere along the line in Banff/Jasper national parks, my wipers
> > would stop working at the same time (as I soon discovered) as the fan
> > for the internal ventilation system would fail. But then they would
> > start working again; almost always (but not 100%) correlated with
> > stopping and then restarting the engine.
>
> > Now, check me on this: according to the manual, the wiper and the
> > ventilation fan are on different circuits, right?
>
> > So does anyone know where I should start looking for the fault? Because
> > I don't get it.
>
> For the NB (not sure about NA, but probably the same) the electrical
> diagram shows that the air-con blower fan / rear defogger(if fitted),
> wipers, and electric windows (if fitted) share a common circuit from the
> main ignition switch (black/red striped wire from ignition switch on NB)
> before the fusebox. *I'd be starting a search there - especially as
> you've observed that it's intermittent depending on stopping and
> restarting. *Likely to be either a dead ignition switch, or trace the
> appropriate wire from ignition switch back though to fusebox for loose
> connection / damaged wire.

That makes tremendous sense, as I just a couple of months ago had to
have my ignition switch replaced because I had my keys stolen and no
one could identify the code for my original keys.

It only goes to show that the surest way to have something go wrong
with your car is to have had something else that was wrong get
"fixed".

<sigh>