eight months and one mud hole
have gone past. On the way home from a 500 mile trip, the "
" light came on. Upon closer scrutiny of the gauges, I saw that
the Volt Meter was full down in the direction of the "9" volt mark.
I cycled power a few times and after indicating the battery charge
(around 10 volts with a large array of electrical items on) it returned
to the "9".
point I decided, believe the gauge or not, it would be a good idea to
power down all unnecessary electrical devices. It was past dark
outside, the temperature was about 25 degrees, and I still had about 1/2
hour to go before I reached home. I knew the
Optima battery would probably support
headlights and the ignition system for that time, but did not want to
push it. So I turned off the
CB, Hands-free phone,
heater fan, 110watt driving lights,
cell phone power,
and flicked the lights to low-beam.
of the drive home consisted of vigilance about the power in the battery
and a little wishing that it would be enough to get home. It
turned out to be fine and I landed in the driveway with time to spare.
I left the vehicle running and opened the hood. Sure enough, the
alternator was making gritty sounds.
caused me to think back a day to a couple things that had caught my
attention but were not investigated. First I got a whiff of an
ozone smell - like the smell of burning truck brakes. I had
dismissed it because there were trucks around and we smell it often near
the highway entrance. I should have paid attention - it is also
the smell of a burnt electrical device (like an alternator). The
other symptom I ignored was a dry metal against metal sound, like the
sound of a disc brake that is on. I figured that was just a normal
noise that I didn't usually notice in my other cars and figured after
not driving the Jeep for a few days I was just being over sensitive...
The outcome was no big disaster, but I am fortunate that the alternator
held up for what was approximately 300 miles past these warning signs.
I was lucky.
I shut off
the Jeep and put the battery on a slow trickle charge to freshen it up,
and the next day, ordered a replacement alternator. I would have
liked for the alternator to last longer than 2 3/4 years, but given some
of the extreme duty it's been subjected, and the number of miles
(~100K), I probably got my moneys-worth. No sense splitting hairs.
about a week for the new alternator to come since the retailer was out
of stock. It came on a cold, wet and snowy day. I installed
it in three waves.
disconnected the battery and wires to the alternator. I located
the proper tools. That took about 10 minutes.
removed the old alternator from the vehicle. That consisted of
removing a nut and two bolts, and fishing the old alternator past air
box, A/C and ignition plumbing and out of the compartment.
install the new alternator, nuts, bolts, belt and reconnecting wires and
Not so fast... After I got everything buttoned back up comes the
test. And wouldn't you know it - though the mechanical problems of
the failing bearing in the alternator is fixed, there still isn't power
coming to the battery. The gauge was still telling me the battery
was not getting any!
rechecked the connections between the alternator and the Power
Distribution Center (PDC). Everything looked fine. I removed
and re-inserted the plug lead (Field terminals). Everything looked
fine there too. Still no power... So I dug into the service
manual. Not a lot of clues, at least no "troubleshooting guide".
But I took a look at the wiring chart and found something interesting.
A fusible link between the alternator and the PDC. Sounds like a
likely culprit. Remember that electrical burning smell?
Perhaps the alternator shorted and the fusible link did it's job?
I will check the wire and see if that's the problem...
and checked the wire. It has continuity. So that's not the
problem. I was disappointed because this would be a relatively
easy fix. According to the manual, it could still be the
alternator, the voltage regulator in the Powertrain Control Module...
for free time, I buttoned it all up so that it could be driven, albeit
without charging the battery.
contacted my supplier and got another alternator. After repeating
the exercise, I still had the same result. No charging. It
seemed unlikely that the alternator was the problem. Just to be
sure I took three alternators to Advance Auto to be bench checked.
technician looked up my vehicle and using the connectors specified,
mounted my alternator on the testing device and in turn tested each of
the three units I had brought along. The first was the alternator
I had removed in the beginning of the problems. As expected, the
technician observed that the bearings were bad, but surprisingly
indicated that the alternator was still producing power. That told
me everything I needed to know - it was something other than the
further reference I had him test a second alternator - one that Jeff at
Adrenaline Offroad had given me. He told me it was "No Good".
And indeed, the technician diagnosed this one as having good bearings
but "dead" (not producing any power). So that told me the test was
where it gets interesting. I had him test the new Mean Green
alternator that I had first received from Jeff. This one indicated
it was producing 22 volts! Soon the drive belt started smoking on
the test machine so the technician shut it down. But I am not sure
that means the alternator is bad. Remember, the factory alternator
that I had in my vehicle is a 117-amp unit. When the test machine
was set up, the technician calibrated the test for a 117a alternator.
The way the voltage regulator works is to send current to the field
terminals. This "tells" the alternator to produce power. I
expect the field terminal voltage is designed in test mode to get the
alternator to produce maximum power. So if the test unit is
measuring volts coming from the alternator but assuming the amperage is
117 amps, I think it will calculate the voltage incorrectly and read
high. So I was not convinced the alternator is bad. But that
didn't fix my problem. So what if I had a good alternator?
That was part of my problem solved, but I still didn't have my charging
I ran the
wiring chart through my head again and the only thing I had not verified
was the Powertrain Control Module (PCM), also know as "the computer".
integrated voltage regulator is "embedded" in the PCM and is not
serviceable as a separate part. The solution is to replace the PCM,
or hack in an external voltage regulator. Sadly, given my
experience with hacking in a voltage regulator in my E-Type Jag and the
long-term pain that ended up being, I decided to purchase the PCM and
because of schedule constraints, have it done at the dealer. In
any case, the PCM must be configured by the dealer according to the
vehicle VIN. So that was something beyond my ability to accomplish
even if I did have time to bolt in the new PCM and plug in the cables.
say that the whole thing cost me nearly as much as the AEV high-fender
and hood kit I had been contemplating. I have a healthy charging
system now, but will have to postpone that low center of gravity/33"
tire combo I was considering...