help,,,Location of ballast resistor wire on '81 Ford F150
Terry Vanpool
wire was wrapped in the harness near the starter relay. Unwrap about 6" of
the harness, starting at the starter relay and if it is there, it will be
easily identifiable. But this the resistor is just a piece of wire, it is
unlikely to be bad. If you are getting excessive voltage at the coil with
the ignition switch in the "RUN" position the most likely problem is in the
ignition switch. The switch has internal contacts that supply full voltage
to the coil in the "START" position and should drop back to reduced voltage
in the "RUN" position. At least that is what I would check first.
"Toby Bristow" <dakot...@psnw.com> wrote in message
news:01bfc6c2$6b04e060$33f0...@dakotasams.psnw.com...
> Hello all,
>
> Can anyone tell me a somewhat specific location of the resistor wire for
> the ignition circuit? I know it's somewhere in the loop between the
> ignition module, the key ignition switch, and the coil. It's supposed to
> have between .8 and 1.6 ohms resistance and I've got 104 ohms resistance.
> Needless to say I believe it has alot to do with my problems. I'm getting
> 11.4 volts at the positive terminal of the coil with the ignition on -
> engine not running, and 17.8 volts with the engine running. Spec is 6-8
> volts.. Is it in the harness under the dash or under the hood or does it
> run from the key ignition switch throught the firewall out under the hood.
> Please help. I don't want to do any unnecessary unwrapping of the
harness.
>
> Thanks for any advice
> Toby
>
>
Toby Bristow
Toby Bristow
I believe you're correct. I do recall fuseable links in that area and it
makes since that the resistor wire would be in that location as well. The
ignition switch has been replaced by the owner with no change. The problem
is the truck will suddenly just die. After a few minutes it'll restart
just fine. I suspect the coil is overheating. I was getting 22 volts at
the coil with the engine running. Yikes!!! I replaced the voltage
regulater and that dropped it down to 17.8, but that is still way over
spec. (6-8 volts) There has got to be something wired incorrectly or a bad
wire/connection somewhere. The voltage for the entire truck has a constant
surge/cycle with the engine running as well. I jokingly call it a
heartbeat, but my buddy-owner isn't laughing.
Thanks
Toby
Terry Vanpool <tvan...@ev1.net> wrote in article
<FlmX4.63480$g41.2...@news-west.usenetserver.com>...
Ed Matthews
wrote:
>have between .8 and 1.6 ohms resistance and I've got 104 ohms resistance.
>Needless to say I believe it has alot to do with my problems. I'm getting
>11.4 volts at the positive terminal of the coil with the ignition on -
>engine not running, and 17.8 volts with the engine running. Spec is 6-8
>volts.. Is it in the harness under the dash or under the hood or does it
Is this a "12 volt" truck? What is the voltage at the battery or the
alternator with it running? If you have 17+ volts there, you need to
do something about the voltage regulator. Is it bubbling battery
electrolyte out the vents? I wonder if you have a bad or intermittent
connection somewhere in the regulator circuit that makes the voltage
run so high. Are you confident the meter you're using is accurate?
Checking it against another meter may be something you want to try.
Let us know how this comes out!
Ed Matthews
Brookline MO USA
(please watch out for the anti-spam in the return address.)
Toby Bristow
No, I've not checked it against another meter but I can promise you I will.
I use it several times a week, usually on basic stuff and now that I think
about it, it could be reading alittle high but not that much. Too many
different cars within spec for it to be that far off. Even if the meter is
off scale, I have defenitly got a problem. I've never seen a vehichle
running at this high of voltage consistantly. If I increase the load
(headlights & accessories) the regulater compensate. It's also brand new.
When I put the engine in (3rd engine for this truck) the wiring and vacuum
systems were mangled. Wires and hoses going everywhere and nowhere.
Duraspark III ignition, which isn't very well documented. So, I did the
best I could. It's much, much, much better than before but still not
right.
thanks for the ideas
Toby
JJ
The ballast resistor was for "POINTS" type distributors, so they wouldn't
burn up quickly, Electronic ignition has no such problem. The coil is
switched by solid-state circuits not points.
the 17.8 at the coil is a phantom reading, with the engine running your
trying to measure a square wave signal with a voltmeter, + back EMF from
the magnetic field collapsing, you need a scope for that.
JJ
Toby Bristow <dakot...@psnw.com> wrote in message
news:01bfc6c2$6b04e060$33f0...@dakotasams.psnw.com...
> Hello all,
>
> Can anyone tell me a somewhat specific location of the resistor wire for
> the ignition circuit? I know it's somewhere in the loop between the
> ignition module, the key ignition switch, and the coil. It's supposed to
> have between .8 and 1.6 ohms resistance and I've got 104 ohms resistance.
> Needless to say I believe it has alot to do with my problems. I'm getting
> 11.4 volts at the positive terminal of the coil with the ignition on -
> engine not running, and 17.8 volts with the engine running. Spec is 6-8
> volts.. Is it in the harness under the dash or under the hood or does it
Toby Bristow
I know it dosen't have a "ballast" resistor. It's a resistance wire in the
ignition circuit or loop. I'm not familiar with a square wave and why I
can't measure it properly, not to say I don't believe you. But still,
with the engine not running and the ignition in the run position my book
says 6-8 volts at the positive terminal on the coil and I'm getting 11
volts. I finished with the vacuum/emission system last night and delivered
the truck so the owner can get it smogged. (California) It ran much better
and didn't die once so it's improving but it bothers me that my actual
readings don't agree with the book. Oh well. I'll know this system inside
out by the time it's solved.
thanks
Toby
JJ <jo...@nonbicnet.net> wrote in article
<sivgaij...@corp.supernews.com>...
JJ
ok Engine off - key on...
batt +12 -----
ignition-------->resistor-wire--------->coil------------>electronic switch
(???)---->ground
0 ohm | 1.5ohm |
1.6ohm | ~0ohm (closed)
| +12 to ground | ~7V
to ground | ~0V to ground
What you should see | 6-volt drop | 6Volt drop
| ~ 0volts drop when closed
| |
|
What you probably have | +12 to ground | +11.4 to ground |
+11 to ground
voltage drop across | ~ 1 Volt drop | ~1volt drop
| ~ 11 volts drop closed
**DROP measurements are across the devices not to ground.
If you have 11.4 Volts at the coil, the problem is between the
coil---->Electronic switch---->ground
Most likely a bad connector or ground connection giving you the high
resistance, which is where you would see the largest voltage. (ohm's law
E/I*R). So look from the coil/duraspark/ground for the problem,
When the engine is running you have a square wave at the terminals caused by
the current flow interrupted by the triggering device (duraspark). A
meter cannot accurately measure this voltage.