Troubleshooting '89 302 Charging system

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Hank - 11 Oct 2006 05:06 GMT

Hello,

This is on a 1989 F-150. The truck sits for a long time, probably over
six weeks since it was last used. The battery light comes on, and the
(built in) voltmeter is lower than normal, but still in the "OK" range.
If I put an analog meter across the terminals, the battery reads 12
when not running, and about 14 when "charging". I would guess that
both of these numbers are on the low side of "OK". The truck starts
and runs fine, but I don't want to really road test it. Battery is
charged up, and it cranked and started fine after the six week
vacation.

There is a relay next to the coil (on the left cylinder bank) that
keeps on clicking after I shut down the truck, if I smack it it stops.
Also, it seems like, when I first start it, maybe the AC is running
regardless of switch position. I'm not sure, but if I turn the AC on
just after startup, I don't here any difference (from inside the cab),
but when I then turn it off it kind of "thunks" and gets quieter.

Does the light come on below a certain voltage (14.6, 14.9, ??). I'd
think that 14+ volts would charge it up, is that not the case? As I
mentioned, it sat for awhile before this happened. Should I be looking
for corroded connectors, or what?

Thanks for any and all help,

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Backyard Mechanic - 11 Oct 2006 11:47 GMT

> This is on a 1989 F-150. The truck sits for a long time, probably over
> six weeks since it was last used. The battery light comes on, and the
> (built in) voltmeter is lower than normal, but still in the "OK" range.
> If I put an analog meter across the terminals, the battery reads 12
> when not running, and about 14 when "charging". I would guess that
> both of these numbers are on the low side of "OK".

That's the problem with analog meters.. make sure the needle is zeroed,
and compared the reading closely with another 'healthy' charging system.
Also it matters WHEN you take the reading.
If you just shut the truck off, reading will be higher... if battery had
been low, running voltage may read lower.

> The truck starts
> and runs fine, but I don't want to really road test it. Battery is
> charged up, and it cranked and started fine after the six week
> vacation.

That's confusing... do you mean you charged it up during... or that it
stayed fine WITHOUT charging for six weeks?

> There is a relay next to the coil (on the left cylinder bank) that
> keeps on clicking after I shut down the truck, if I smack it it stops.
> Also, it seems like, when I first start it, maybe the AC is running
> regardless of switch position.

Normal .. does that to exercise the compressor, oil to seals, etc.

> Does the light come on below a certain voltage (14.6, 14.9, ??). I'd
> think that 14+ volts would charge it up, is that not the case? As I
> mentioned, it sat for awhile before this happened. Should I be looking
> for corroded connectors, or what?

I've seen two rebuilt alts, for same vintage applications, do the same
thing with nothing wrong with the charging system.
There's a good chance it's just a fault in the volt regulator light
driver.

Are you handy? search google for my alternator refurb tip. Get a spare
from a salvage yard.. cheap insurance

Signature

Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
you pay..DEAL with it!

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Hank - 12 Oct 2006 02:30 GMT

> Also it matters WHEN you take the reading.
> If you just shut the truck off, reading will be higher... if battery had
> been low, running voltage may read lower.

It was about 12 before starting (after sitting for a day or so), and 14
when running.

> > The truck starts
> > and runs fine, but I don't want to really road test it. Battery is
[quoted text clipped - 3 lines]
> That's confusing... do you mean you charged it up during... or that it
> stayed fine WITHOUT charging for six weeks?

It stayed up w/out charging for 6 weeks, cranked and started fine. In
the winter I trickle charge it if it's going to sit too long, but I
didn't do that this time (wasn't worried about it freezing). When I
noticed the light, I put it back away and took another vehicle to work.
My wife put a charger on it that day, but it read fully charged after
about a minute. I repeated this a few days later, so the batttery
appears fine.

> > There is a relay next to the coil (on the left cylinder bank) that
> > keeps on clicking after I shut down the truck, if I smack it it stops.
[quoted text clipped - 12 lines]
> There's a good chance it's just a fault in the volt regulator light
> driver.

It seems the volt meter (built in) is also lower than I remember it
being.

> Are you handy? search google for my alternator refurb tip. Get a spare
> from a salvage yard.. cheap insurance

Thanks, I'll look for it. I was looking for a troubleshooting
procedure. I used to work at a parts counter. A guy would come in for
a battery one day, an alternater the next week, and a voltage regulator
a couple of days later (and often a 3rd battery before he was done). I
don't want to be that guy! I'd guess there's a place I could
disconnect the wiring harnes and measure in order to check out the
alternator w/out the battery load (and any extra shorts).

I'll look for a better manual, but thought alt.trucks.ford might have
the answer!

thanks,

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Whitelightning - 12 Oct 2006 03:09 GMT

General rule of thumb, minimum charge voltage is 13.5 volts, max rate 14.5.
some ricers manuals allow as high as 15.5, but they have short battery life.
Full charged battery should read between 12.2 and 12.6 volts, each cell
produces 2.1 volts, and there are 6 cells in a 12 volt battery. First thing
to do is pull the battery and take it somewhere and have it load tested.
When your sure the battery is good, and has a full charge then you can start
checking other things. if the battery is pulling high amps from the
alternater, the voltage readings can be a false low. A battery with
sulfated plates will pull a load on a battery charger for a very short
amount of time and then the charger will show a low or next to nothing
charge rate giving the impresion the battery is charged fully.

Whitelightning

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MasterBlaster - 12 Oct 2006 12:09 GMT

> > > There is a relay next to the coil (on the left cylinder bank) that
> > > keeps on clicking after I shut down the truck, if I smack it it stops.

Which one?
http://www.autozone.com/images/cds/gif/medium/0900823d800a1874.gif
http://www.autozone.com/images/cds/gif/medium/0900823d800a2d1b.gif

> I'd guess there's a place I could
> disconnect the wiring harnes and measure in order to check out the
> alternator w/out the battery load (and any extra shorts).

Disconnect the battery with the engine running? (aka: the quickest way
to fry the alternator, regulator, radio, ECU, and everything else electronic
in the vehicle). I thought we'd warned enough folks on the newsgroup that
nobody did that anymore. I guess not.

Reply to this Message

Hank - 12 Oct 2006 18:18 GMT

> > > > There is a relay next to the coil (on the left cylinder bank) that
> > > > keeps on clicking after I shut down the truck, if I smack it it stops.
>
> Which one?
> http://www.autozone.com/images/cds/gif/medium/0900823d800a1874.gif
> http://www.autozone.com/images/cds/gif/medium/0900823d800a2d1b.gif

I just smacked the round thing in front of both relays. I guess I
rocked the assembly enough to make whichever one it was stop. I'll try
again and feel/listen for which relay it is.

> > I'd guess there's a place I could
> > disconnect the wiring harnes and measure in order to check out the
[quoted text clipped - 4 lines]
> in the vehicle). I thought we'd warned enough folks on the newsgroup that
> nobody did that anymore. I guess not.

I figured I'd need to put some load across the terminals before I
disconnected the alternator from the rest of the car. Hence the
question. Back in the day, I seem to recall a standard load that we'd
use to test them. It was a big box, about half as big as a battery.
If we didn't have that (special tool #xyz) we'd just use another
battery. I'd guess that modern systems are much easier to mess up, so
I thought I'd ask first.

Thanks for the link to the picture, that's a useful resource.

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Backyard Mechanic - 11 Oct 2006 11:55 GMT

> There is a relay next to the coil (on the left cylinder bank) that
> keeps on clicking after I shut down the truck, if I smack it it stops.

Well, then??... replace it.

Signature

Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
you pay..DEAL with it!

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Hank - 12 Oct 2006 02:32 GMT

> > There is a relay next to the coil (on the left cylinder bank) that
> > keeps on clicking after I shut down the truck, if I smack it it stops.
>
> Well, then??... replace it.

What is it?

And is it not supposed to do that? My Bronco II used to make all sorts
of clicking and relay noises after you shut it down. At the time
(early 80s) I was told that it was normal.

Thanks,

> --
> Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
> you pay..DEAL with it!

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Joe - 12 Oct 2006 05:39 GMT

>> > There is a relay next to the coil (on the left cylinder bank) that
>> > keeps on clicking after I shut down the truck, if I smack it it stops.
[quoted text clipped - 8 lines]
>
> Thanks,

I have a 89 F150 and I don't have anything clicking there. I don't know what
it is either. Sounds wrong to me.

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