Lately we have been having some crapy weather here and i noticed that if i have my lights, windshield wipers, and the defroster on when i come to a stop light and my 86 idels the voltmeter in the gauges drops dramatically down into the red but if i hold the rpm at about 1500 it jumps back up and everything is okay. is this normal or is my altenator going out or is the voltage regulator bad?????

well it could be a few things.
check the belts tight.
get a voltmeter over the battery terminals and with the engine running check the volts at idle.should be over 12v
now turn on loads of electrical stuff and the alternator should bump up the charge to 13+volts(more likely 14+)
if the volts dont rise then the alternater is suspect

dont forget to check simple things such as loose battery terminals and corroded earth connections

Here is a diagram that might help your problem. I had the same this fixed it. Basically when I was turning on my wiper motor the clock fluctuated, the voltmeter went way down.

Bob Lawbla
74 Spider
79 X 1/9 (first owner)

Could be a number of problems - most likely is a bad connection to the alternator itself. Virtually every X1/9 I have ever been in has had the same fault!

You need to check all the engine earths and preferably replace the brown wire (which takes most of the current) to the fuse box. You should also look at getting relays wired in for the dipped beam circuits as the lack of relays results in the steering column switch melting.

With the brown wire mod and the relays you should find everything works better.

I found that the brown wire was too small for the load. But the real problem that I had/was a bottle neck at the connector of the white block connector and also the ignition switch. These two points actually overhead considerably/dangerously even if they were cleaned.

Starter motor problem ( I should starts a new thread for this one):
I don't have that instrument electrical problem any more, but have a starting problem. I will attack that starting problem in the spring once out of storage. I have had this inconsistent problem since I owned the car.

The problem is that it will make that solenoid knocking sound but the starter won’t turn most of the time. I rebuilt 3 starters, cleaned connectors, installed a ground strap at the starter, still have this intermitted problem.

I suspect that the wire between starter solenoid and the ignition switch is dirty along the way or it’s again too small. Once out of the storage I will make wire heat test and calculate the size to match its load. That wire is a 12AWG driving the solenoid (and its inner return spring) and the first stage of starting and engagement of the starter motor. Yes the starter motors! That small wire is actually driving the starter for a fraction of seconds before the main big electrical cable enters in action. A wire that size could only drive 20Amp considering 20feet long. This circuit is not protected. A free running starter motors probably pulls around 100amp at the peak stage. It is intermitted probably because it is almost there to make a contact.

What do you think?

Bob