zecc81

I wouldn't exactly call this a problem, I'm just wondering if this is normal.

When I first cold start the car, the voltage gauge reads 12V. After a little warm up I start driving and at the very moment when I first go past PRECISELY 3000 rpms, the voltage will jump up to 14V and remain there for the rest of the journey. At night I also notice the interior lights will be dim at 12V, but brighten up after I hit 3k and have 14V.

The only problem I notice is the wipers really struggle when I'm at 12V.

I've had no charging problems. Car seems to run fine at 12V, but as we all know it's nearly impossible to drive around in a rotary while keeping it under 3k, so I never end up driving with 12V for long.

Not an issue on warm starts as the engine usually revs past 3k and jumps to 14V immediately.

turboIIrotary

iTrader: (9)

It should be running at 14v while at idle too your alternator sounds like it is going out.

john ward

iTrader: (7)

Or its not getting the exciter voltage. When you rev it up the alternater self excites.

HAILERS2

Listen to this guy. He knows what he's talking about.

Get a digital meter out. Go to the small two wire plug on the alt. Pull the plug off.

With the key to ON engine OFF check the two wires in the plug. Both should show batt voltage.

IF your car is a series four car the WHITE/black wire is the excitation wire and should have batt voltage. It is fed thru the COIL of the Alt relay in the CPU via the METER FUSE. IF your gauges work then the meter fuse is good.

The BLACK/white wire is fed by the ENGINE fuse and you know the engine fuse is good if the car starts up so no need to look at that fuse.

IF the alternator does not see excitation voltage it will not put out. BUT there is residual magnatizim in the rotor of the alt so if you rev the engine up it will self excite itself..............what your doing at 3 grand as you said.

IF the car is series four and all the warning lights come on when the keyh is put to ON, then I'd say the White/black wire should be getting voltage unless it fell off.

IF yours is a series five you should have said so and I might have mentioned the two wire colors in the series five alt small plug. But.........

Actually if the alt is self exciting itself..................who cares? It will still regulate the voltage when the diode assy in the alt starts feeding the field of the alternator. So.......no rush to fix it imho. I could be wrong though.

RotaryEvolution

iTrader: (30)

this thread is getting me all EXCITED!


beat it with a hammer, that always fixes it.

zecc81

Okay, so it sounds like something might be slightly wrong with the alternator. I've had the car for about 9 months and every time, without fail, the voltage rises to 14V after 3k rpms. I've never had any issues with low battery so I'll leave good enough alone.

arad99

iTrader: (2)

You might want to check the tension on the alternator belt. Might be slipping at lower rpms.

lunardeathgod

CHECK YOUR GROUNDS!!!

trust me :p

StevenL5975

My car does the exact same thing, voltage goes up at 2500 rpm.
Alt and belt is new, tension is good so no slip.

My warning lights never come on all together when I put the key in to ON.

I will do some measuring today.

HAILERS2

It is not a ground problem. The guts of the alternator get their gnd thru the body of the alternator making contact with the engine block via the spacer and attach bolts. It the engine wasn't grounded the car wouldn't start.

zecc81

I've checked that, tension seems right on spec.

My warning lights don't all come with the ignition either, might be related. I second the

HAILERS2

If you have a 86 or 87 car and the warning lights don't come on, then listen up.

There is a relay in the CPU near your left foot that causes the warning light assy to all bulb light up when the key is put to ON.

This relays coil has power on it anytime the key is to ON. All it's looking for is a ground on the relays coil for it to pull in and then send a ground signal to the warning light assy to turn the warning lights all on.

How can you check the relay in the CPU to see if it's working? Easy. Go to the alternators small plug and pull the plug off the alt. Find the WHITE/black wire in the plug (NOT THE BLACK/white wire).

Put the key to ON. Now with a piece of wire bare at each end, put one end of that wire to gnd (the alt housing is a good gnd) and the other end of the wire into the socket on the plug that has the white/black wire.

When you do this you should hear a click from the CPU......meaning the relay did pull in. Do this several times listening for the click of the relay.

IF the relay clicks, then I suggest the output from the relay to the CPU is an open circuit most likely.

How to be sure? Easy. Go to the CPU and pull the plug off it that has the white/black and yellow/blue wires in it. Put a gnd on the yellow blue wire with the key ON. The warning lights should all light up. IF they do NOT and the METER fuse is good, then the problem lies in the warning light assy. IF the lights do all light up, then the problem lies probably in the cold solder joints in the CPU's plug. Actually not the plug but the jack the plug goes on. Reflow the solder in the CPU's jack and that should fix it.

IF the warning lights did not light up with a gnd on the yellow/blue wire with key ON, then reflow the solder in the Warning light assys/jack.

The warning lights all come on due to the guts of the alt putting a gnd on the white/black wire in the small plug on the alt. And as I said that gnd signal causes the alt relay in the CPU to pull in and in turn put a gnd on the yellow/blue wire that goes to the warning light assy. Just as the wiring diagram shows. I might attach it if the site lets me.

HAILERS2

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