97 Explorer electrical problem - Help!

I have a 1997 XLT 4dr, 4WD Explorer with 5-spd manual. It has been
essentially trouble-free for almost 250K miles and we've routinely used it
to haul a utility trailer. It came with trailer-prep, so when it was brand
new I had picked up a Hopkins trailer adapter that plugged into the wiring
harness under the left rear of the vehicle and everything always worked
well. This past weekend we hauled my son's furniture home from college after
graduation and the next day made several trips to a storage facility to
store things. After the last trip, we smelled an electrical burn when
pulling in the driveway and found the trailer wiring pigtail (from the
hopkins "T" to the trailer plug) was fried. I unplugged it from the trailer
and parked the trailer. The truck and all lights were working fine, so my
son drove it on to work that evening and returned home afterwards. I had
tried to pull the fried pigtail from the hopkins T, but it was stuck, and
since my son needed to leave we just left it, thinking there was a short on
the trailer somewhere.

Today we found the truck battery dead, really dead, like less than 2 volts.
We tried jumping it, but the jumper cable got hot enough to melt the clamp
insulation, so we pulled the battery and replaced it with a fresh battery.
The replacement battery voltage dropped from 12v to 5 volts in a matter of
seconds and, again, the truck wouldn't turn over. I removed the Hopkins T
from the connector, but the same symptoms exist. No fuses have blown. I
looked at the Auxiliary Relay Box #4 above and in front of the rear wiper
fluid box, but none of the wiring is obviously stressed, and it is not
obvious how to open, or drop, or otherwise get into the box to pull relays.
Any ideas? This has me somewhat dismayed and alarmed at this point.

=Vic=
Bear Gap, PA

Follow-up to this problem...

While none of the instrument panel fuses were blown, I pulled all of the
Maxi-Fuses in the Power Distrubution Box under the hood and found the 20a
trailer tow fuse (#7) blown. However, even with ALL the Maxi-fuses pulled I
still draw an arc and drop battery voltage to 9v or less as soon as it is
hooked up. Is there a diode across the 12v system somewhere before the power
distribution box?

=Vic=

"Vic Klein" > wrote in message
...
>I have a 1997 XLT 4dr, 4WD Explorer with 5-spd manual. It has been
>essentially trouble-free for almost 250K miles and we've routinely used it
>to haul a utility trailer. It came with trailer-prep, so when it was brand
>new I had picked up a Hopkins trailer adapter that plugged into the wiring
>harness under the left rear of the vehicle and everything always worked
>well. This past weekend we hauled my son's furniture home from college
>after graduation and the next day made several trips to a storage facility
>to store things. After the last trip, we smelled an electrical burn when
>pulling in the driveway and found the trailer wiring pigtail (from the
>hopkins "T" to the trailer plug) was fried. I unplugged it from the trailer
>and parked the trailer. The truck and all lights were working fine, so my
>son drove it on to work that evening and returned home afterwards. I had
>tried to pull the fried pigtail from the hopkins T, but it was stuck, and
>since my son needed to leave we just left it, thinking there was a short on
>the trailer somewhere.
>
> Today we found the truck battery dead, really dead, like less than 2
> volts. We tried jumping it, but the jumper cable got hot enough to melt
> the clamp insulation, so we pulled the battery and replaced it with a
> fresh battery. The replacement battery voltage dropped from 12v to 5 volts
> in a matter of seconds and, again, the truck wouldn't turn over. I removed
> the Hopkins T from the connector, but the same symptoms exist. No fuses
> have blown. I looked at the Auxiliary Relay Box #4 above and in front of
> the rear wiper fluid box, but none of the wiring is obviously stressed,
> and it is not obvious how to open, or drop, or otherwise get into the box
> to pull relays. Any ideas? This has me somewhat dismayed and alarmed at
> this point.
>
> =Vic=
> Bear Gap, PA
>

My first guess would be the alternator.

"Vic Klein" > wrote in message
...
> Follow-up to this problem...
>
> While none of the instrument panel fuses were blown, I pulled all of
> the Maxi-Fuses in the Power Distrubution Box under the hood and
> found the 20a trailer tow fuse (#7) blown. However, even with ALL
> the Maxi-fuses pulled I still draw an arc and drop battery voltage
> to 9v or less as soon as it is hooked up. Is there a diode across
> the 12v system somewhere before the power distribution box?
>
> =Vic=
>
> "Vic Klein" > wrote in message
> ...
>>I have a 1997 XLT 4dr, 4WD Explorer with 5-spd manual. It has been
>>essentially trouble-free for almost 250K miles and we've routinely
>>used it to haul a utility trailer. It came with trailer-prep, so
>>when it was brand new I had picked up a Hopkins trailer adapter that
>>plugged into the wiring harness under the left rear of the vehicle
>>and everything always worked well. This past weekend we hauled my
>>son's furniture home from college after graduation and the next day
>>made several trips to a storage facility to store things. After the
>>last trip, we smelled an electrical burn when pulling in the
>>driveway and found the trailer wiring pigtail (from the hopkins "T"
>>to the trailer plug) was fried. I unplugged it from the trailer and
>>parked the trailer. The truck and all lights were working fine, so
>>my son drove it on to work that evening and returned home
>>afterwards. I had tried to pull the fried pigtail from the hopkins
>>T, but it was stuck, and since my son needed to leave we just left
>>it, thinking there was a short on the trailer somewhere.
>>
>> Today we found the truck battery dead, really dead, like less than
>> 2 volts. We tried jumping it, but the jumper cable got hot enough
>> to melt the clamp insulation, so we pulled the battery and replaced
>> it with a fresh battery. The replacement battery voltage dropped
>> from 12v to 5 volts in a matter of seconds and, again, the truck
>> wouldn't turn over. I removed the Hopkins T from the connector, but
>> the same symptoms exist. No fuses have blown. I looked at the
>> Auxiliary Relay Box #4 above and in front of the rear wiper fluid
>> box, but none of the wiring is obviously stressed, and it is not
>> obvious how to open, or drop, or otherwise get into the box to pull
>> relays. Any ideas? This has me somewhat dismayed and alarmed at
>> this point.
>>
>> =Vic=
>> Bear Gap, PA
>>
>
>

If you haven't already done it I would disconnect the battery and check for
a short to ground at the positive battery cable. If yes then disconnect the
cable from the starter selenoid and see if it goes away. If not then
disconnect the cable from the starter motor. If not then disconnect the red
wire from the starter relay and keep going until you find the short. If
it's not there then, like already suggested, check the alternator for a
short. There are diodes in the alternator that could be shorted out and
might account for battery drain.


"Vic Klein" > wrote in message
...
> Follow-up to this problem...
>
> While none of the instrument panel fuses were blown, I pulled all of the
> Maxi-Fuses in the Power Distrubution Box under the hood and found the 20a
> trailer tow fuse (#7) blown. However, even with ALL the Maxi-fuses pulled
I
> still draw an arc and drop battery voltage to 9v or less as soon as it is
> hooked up. Is there a diode across the 12v system somewhere before the
power
> distribution box?
>
> =Vic=
>
> "Vic Klein" > wrote in message
> ...
> >I have a 1997 XLT 4dr, 4WD Explorer with 5-spd manual. It has been
> >essentially trouble-free for almost 250K miles and we've routinely used
it
> >to haul a utility trailer. It came with trailer-prep, so when it was
brand
> >new I had picked up a Hopkins trailer adapter that plugged into the
wiring
> >harness under the left rear of the vehicle and everything always worked
> >well. This past weekend we hauled my son's furniture home from college
> >after graduation and the next day made several trips to a storage
facility
> >to store things. After the last trip, we smelled an electrical burn when
> >pulling in the driveway and found the trailer wiring pigtail (from the
> >hopkins "T" to the trailer plug) was fried. I unplugged it from the
trailer
> >and parked the trailer. The truck and all lights were working fine, so my
> >son drove it on to work that evening and returned home afterwards. I had
> >tried to pull the fried pigtail from the hopkins T, but it was stuck, and
> >since my son needed to leave we just left it, thinking there was a short
on
> >the trailer somewhere.
> >
> > Today we found the truck battery dead, really dead, like less than 2
> > volts. We tried jumping it, but the jumper cable got hot enough to melt
> > the clamp insulation, so we pulled the battery and replaced it with a
> > fresh battery. The replacement battery voltage dropped from 12v to 5
volts
> > in a matter of seconds and, again, the truck wouldn't turn over. I
removed
> > the Hopkins T from the connector, but the same symptoms exist. No fuses
> > have blown. I looked at the Auxiliary Relay Box #4 above and in front of
> > the rear wiper fluid box, but none of the wiring is obviously stressed,
> > and it is not obvious how to open, or drop, or otherwise get into the
box
> > to pull relays. Any ideas? This has me somewhat dismayed and alarmed at
> > this point.
> >
> > =Vic=
> > Bear Gap, PA
> >
>
>

Thanks. I gradually disconnected everything from the starter solenoid and
still had the voltage drop at the battery. Looking at the schematics, I saw
that one line runs straight from the battery to a second solenoid contact in
the starter. Dropping the line to the starter and jumpering to everything
else on the starter solenoid, including everything on the power distribution
box, showed the rest of the system was OK. I guess this is truly a
coincidence, but it appears the starter failed (always connected to the
battery) within a day of the trailer short. The truck is getting a new
starter now.

=Vic=

"Ulysses" /> wrote in message
...
> If you haven't already done it I would disconnect the battery and check
> for
> a short to ground at the positive battery cable. If yes then disconnect
> the
> cable from the starter selenoid and see if it goes away. If not then
> disconnect the cable from the starter motor. If not then disconnect the
> red
> wire from the starter relay and keep going until you find the short. If
> it's not there then, like already suggested, check the alternator for a
> short. There are diodes in the alternator that could be shorted out and
> might account for battery drain.
>
>
> "Vic Klein" > wrote in message
> ...
>> Follow-up to this problem...
>>
>> While none of the instrument panel fuses were blown, I pulled all of the
>> Maxi-Fuses in the Power Distrubution Box under the hood and found the 20a
>> trailer tow fuse (#7) blown. However, even with ALL the Maxi-fuses pulled
> I
>> still draw an arc and drop battery voltage to 9v or less as soon as it is
>> hooked up. Is there a diode across the 12v system somewhere before the
> power
>> distribution box?
>>
>> =Vic=
>>
>> "Vic Klein" > wrote in message
>> ...
>> >I have a 1997 XLT 4dr, 4WD Explorer with 5-spd manual. It has been
>> >essentially trouble-free for almost 250K miles and we've routinely used
> it
>> >to haul a utility trailer. It came with trailer-prep, so when it was
> brand
>> >new I had picked up a Hopkins trailer adapter that plugged into the
> wiring
>> >harness under the left rear of the vehicle and everything always worked
>> >well. This past weekend we hauled my son's furniture home from college
>> >after graduation and the next day made several trips to a storage
> facility
>> >to store things. After the last trip, we smelled an electrical burn when
>> >pulling in the driveway and found the trailer wiring pigtail (from the
>> >hopkins "T" to the trailer plug) was fried. I unplugged it from the
> trailer
>> >and parked the trailer. The truck and all lights were working fine, so
>> >my
>> >son drove it on to work that evening and returned home afterwards. I had
>> >tried to pull the fried pigtail from the hopkins T, but it was stuck,
>> >and
>> >since my son needed to leave we just left it, thinking there was a short
> on
>> >the trailer somewhere.
>> >
>> > Today we found the truck battery dead, really dead, like less than 2
>> > volts. We tried jumping it, but the jumper cable got hot enough to melt
>> > the clamp insulation, so we pulled the battery and replaced it with a
>> > fresh battery. The replacement battery voltage dropped from 12v to 5
> volts
>> > in a matter of seconds and, again, the truck wouldn't turn over. I
> removed
>> > the Hopkins T from the connector, but the same symptoms exist. No fuses
>> > have blown. I looked at the Auxiliary Relay Box #4 above and in front
>> > of
>> > the rear wiper fluid box, but none of the wiring is obviously stressed,
>> > and it is not obvious how to open, or drop, or otherwise get into the
> box
>> > to pull relays. Any ideas? This has me somewhat dismayed and alarmed at
>> > this point.
>> >
>> > =Vic=
>> > Bear Gap, PA
>> >
>>
>>
>
>