SCOTTC COATES wrote:
> (By the way, why does my useless shop manual and
> owner's manual tell me I have an ammeter??)
The early TR6s had an ammeter, and the later TR6s had
a voltmeter. I believe that the switchover occured
with the 1973 model year. (ie 1969-1972 had an ammeter
and 1973-1976 had a voltmeter.) The voltmeter/ammeter switchover
occurred at the same point that the minor gauges were flipped
over. (On early cars, the needles point to the floorboards, on
later cars, the needles point skywards...)
> On Sunday I took the LBC out with my yard ape (son)
> and we were back to ground zero - the car runs great,
> but all of the electricals are fizzing out one-by-one, and
> the ammeter (sic volt meter) is back down to 11 volts.
The problems you are having sound like classic low voltage
problems. Different components require varying amounts of
voltage, so they don't all stop working at once. (By the way, if
the readout is in volts, it is a voltmeter. :-))
It may be the case that the alternator and battery are working just
fine, and that there is a problem elsewhere in the wiring harness.
(Most likely a bad ground.)
A necessity in diagnosing this further is a decent troubleshooting
voltmeter. Personally, I would suggest, for any amateur mechanic
whose car has an electrical system, that one get a decent digital
autoranging multimeter that will measure at least voltage,
resistance, and have an "audible" continuity tester. (Basically,
an audible continuity tester will emit a high tone (beep) when the
two electrodes are connected. This allows for quick and easy
examination for broken wires and bad grounds.) My own preference
is for a Fluke 77 meter.
(http://www.fluke.com/autotools/products.htm) (No, I don't work for
Fluke, I'm just a happy customer.)
If you don't have a multimeter now, and don't want to buy one, find
somebody that has one you can borrow.
Then, armed with this new tool, you can measure the voltage at the
battery when the car is off. (By placing the two electrodes on the
battery terminals. This should read about 11.5 - 12.5 for a
charged battery.)
When the car is running, measure the voltage at the alternator
output. This should be approximately 13.0-14.0 volts. Measure the
voltage at the battery terminals. This should also be
approximately 13.0-14.0 volts. (It will probably read about 0.1-0.3
volts less than the alternator output, depending on how good the
electrical connections are.)
If the above all tests ok (I speculate it may), then your basic
electrical charging system is ok, and the problems are elsewhere in
the wiring harness. It may be that a previous owner has wired the
alternator directly to the battery, and that the battery ground
strap has a poor connection.
Alternatively, it may be that one of your electrical components (or
wires) has a short in it somewhere, and is diverting a lot of
current from your system. This can be found by turning
everything off, and seeing if your dash voltmeter looks ok. If so,
turn things on one at a time (waiting at least a minute after each
is turned on) and seeing if the voltmeter drops. If you find
something that causes the problem, you can investigate it more
closely using your new multimeter.
--ken
'74 TR6 Daily Driver
Kenneth B. Streeter | EMAIL: streeter@sanders.com
Sanders, PTP2-A001 |
PO Box 868 | Voice: (603) 885-9604
Nashua, NH 03061 | Fax: (603) 885-0631
|