Could be bad battery, not charging, bad connection(s) in the heavy current
circuit, heavy leak when parked, plus possibly others.
Battery first. Connect a voltmeter to the battery posts (not the
connectors) and try to start the car. If the battery voltage here drops to
2v or so then the battery is flat or bad. Give it a good charge and try the
test again. Still drops? Bad battery.
If that is OK leave the battery disconnected for a few days then try again.
If the voltage at the battery terminals drops now the battery is bad.
If the voltage at the battery reads 12v but the car still doesn't crank and
you only have 2v on a brown (better place to test than purple) then you have
bad connections. Have a look at the web site below for how to test the
complete heavy current circuit (not just the grounds) - select 'Spanners',
'Electrics' and 'Bad Connections'.
If the car starts with a newly charged battery measure the voltage on a
brown at fast idle, you should see about 14v. If it only reads 12v or so
then the alt is not charging.
Switch off, disconnect the battery ground strap and connect a test-lamp in
its place. If the lamp glows at all with things like boot lid and doors
closed and nothing switched on you have a leak. Pull the alternator plug
and if the lamp stops glowing the alt is bad. If the test-lamp still glows
the fault is on the brown or purple circuits, pull the bottom fuse, if the
lamp goes out the leak is on the purple otherwise it is on the brown. There
are also in-line fuses in the brown for things like hazard flashers.
PaulH.
http://freespace.virgin.net/paul.hunt1/
(or if that URL doesn't work try )
(http://194.168.54.52/paul.hunt1 )
---- Original Message -----
From: John R. Boehmke <mtbills@mcn.net>
To: <mgs@autox.team.net>
Sent: Monday, March 27, 2000 12:32 AM
Subject: Electrical Problems
> Two weeks ago I was driving my 77MGB around with the top down (not bad for
> Montana in March), and it was running great. Stopped at my daughters
> house,and when I went to leave it clicked once then nothing. I heard what
I
> thought was the starter motor running without engaging, so I figured bad
> solenoid. As it has 92,000 miles on it I thought it would be good to
> replace the starter also. I ordered one from Moss Motors,and put it in
> yesterday. Turned the key, it cranked a couple of times, then nothing.
> Checked the battery and it was low, so I charged it up. Today turn the key
> one grind then nothing. What concerns me is that nothing works on the
whole
> car. I get 12 volts to the purple wire circuit, but when I turn something
> on it doesn't work and the purple circuit drops to 2 volts. My lights
don't
> work, and, with the ignition on, the wipers and turn signals don't work.
> Also, with the ignition on, I only get 2 volts to my coil. I know the DPO
> had his way with the wiring, so there are some different color wires in
> there, but it was running good before this all started. Thanks in advance
> for any hints on what may be my problem. I hate to have it sitting now
that
> the weather is really turning nice.
>
> John
> 77RBB
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