Electrical problems, no charge and strange indications

[jsveb]

I have got problems with the alternator, it is not charging.


Back ground:

I am putting my Carrera 3.0 back together and have fired it up. I have not really driven it yet, but the engine seems to run fine after a top end rebuild by "flat6pac"

The problem:

When I turn on ignition, I have got a charge light. Then when the engine runs at idle, about 1k it dims some. However when I rev the engine the light gets brighter. - yeah that's right, brighter!

When measuring voltage at the batt the voltage drops about 0.3-0.4V when running compared to engine and ignition off.
When testing, the batt V has been between 12.65 and down to about 12.3, so to say, it has been in normal range

The oil pressure indication is also weird, just saying because I don't know if this is somehow linked.
The oil pressure seems to be stuck about 2bar, not real stuck but hesitant to move when I rev it, but sometimes it jumps up to Normal indications. The idiot light works and the sensor has been replaced.
The oil pressure sensor has also been replaced.

Bruce was so kind to lend me to VR, this did not make a difference. On the no-charge situation.

I think I might have seen a jump in V on the Multimeter once, first to about 13v then up to 14v. I am saying might because I have tested so much and am uncertain because it only happens this one time and really quick.

Te alternator is a used core unit, I bought. Mine was working fine, but when I removed it, but the internal wiring was completely shot and beyond repair, so I changed it out.

It is a 70amp ext VR alt.

What have I hooked up wrong?

Suggestions please

For me it sounds like a grounding problem. Did you connect the strap between engine and body? Are the other grounding bolts in the back cleaned before the engine wiring was reconnected?

Otto

[jsveb]

Everything on the chassis was cleaned sanded and cleaned before hooking up the grounds.

I'll try and check the ground on the engine block to see if that can be it.

Thanks for the feedback, keep it coming.

[jsveb]

I removed the alternator today, hoping it would be the ground strap from the alt hosing to the engine block that was bad - that wasn't it.

I have checked the wires they are hooked up according to my pictures from original disassembly which also corresponds with my Bentley manual.

However, when I check the lugs on my replacement alt, an old one. There are two "D-" lugs on the original alt, there was only one. Do both of these have to be hooked up to ground, brown wire?

Btw, the two alt have got the same part numbers.

It seems the nuts on the "second" lugs haven't been removed for a long time, so I'd say no.

What do you make of it?

[jsveb]

Tried to take the alternator to a local specialist for testing. He said he couldn't do it, so I drove to the local flaps. They wouldn't do it either wouldn't fit safely in their tester...arrgh

Anyways, think I can redneck rig it for a bench test. I just need some information on how to hook up the wires.
I have read threads about it. But am not 100 %, and I don't want to fry anything.

Thanks guys

[timmy2]

Post a picture of the new and old alternators.
If the new one has an internal VR you may need to do the diode mod to your indicator light.

[jsveb]

Originally Posted by timmy2

Post a picture of the new and old alternators.
If the new one has an internal VR you may need to do the diode mod to your indicator light.

Thanks for the feedback

The two alternators are the same, same part numbers. Also both with external VR.

I have been advised to stick with the ext VR version since these are less likely to fail...

Also, I just went ahead, and tried to do the bench test.

I hooked up a charged batt to the B+ lug and also wired the batt plus to the DF to axcited the field.
Hooked batt - pole on D-
Guess what, by using a strong piece of string with the alt in a bench vise, I could make an output of about 13,5v on the +61 lug.

From this prelim. test, it seems the alt is ok.

What else could it be, the VRs has been replaced in the troubleshooting already???

[jsveb]

Impatience, I know, but I need this car on the road ASAP.

Any ideas about what I might have done wrong in case it is not the alternator?

I am pretty sure the tranny to chassis ground strap is good, but I'll check it again tomorrow.

[timmy2]

OK, How many new external VR's do you have?
The reason I ask is if the Alt is good, then the new VR may not be.
Logic behind this is based on the light in the dash being a part of the excitation circuit for the alternator.
Maybe a bad ground at the gauge in the dash, but possibly a bad VR.
I bought 2 when my VR went bad, so far so good with the first one.

[timmy2]

Blue wire goes from alt to 14 pin connector to indicator light and VR, red and black wire on light goes to 12v and power all over the place.
Light goes on when there is an imbalance of voltage (Difference) So somewhere there is a voltage drain on the blue wire, most likely the VR. Or you have a short in your harness somewhere.....

[jsveb]

Originally Posted by timmy2

OK, How many new external VR's do you have?
The reason I ask is if the Alt is good, then the new VR may not be.
Logic behind this is based on the light in the dash being a part of the excitation circuit for the alternator.
Maybe a bad ground at the gauge in the dash, but possibly a bad VR.
I bought 2 when my VR went bad, so far so good with the first one.

Thanks Timmy,

I have tried a total of three VRs, the one I originally had which worked fine when I took the car Apart. I have also borrowed to used ones from a fellow pelican.

I'll check ground behing the gauges, and also G1 in the engine bay

[E Sully]

A few pictures of your alternator and regulator wiring would help. Have you made sure the ground strap from the electrical console to the frame is connected?

[jsveb]

Sully, thanks for the help

The wiring is stock and seems to be in good condition.

I have checked grounding from G1 to the relay panel. It is good. In fact I checked continuity on everything that is supposed to grounded, I found nothing that was not good.

I will post pictures, but it is just stock.

I tried to measure resistance in the different VRs on a bench.
The old one was about 1350ohms on both the D+ and DF to the mounting bracket where as the two units I borrowed only have an equivalent reading of 72.5 ohms. I don't know, if I can use that for anything, but I just wonder.

[jsveb]

Last night I put it all back together. Before putting the belt back on I tried to see if I could replicate my bench test, this time having the VR excite the field.
With the key. In the run position, nothing, no indication at all on the MM.

I put the belt back on and fired it up, it doesn't charge at all.

The weird thing is when I fire it up the engine oil pressure goes up to about 4 bar, within a couple of seconds it drops down to about two, where it kind of stays.

What have I hooked up wrong?

Last night I studied the wiring diagrams and will try to see if I have messed up, when I put it all back in.
I did pull out allt the gauges before going back in. There is no sign of magic smoke, so I guess that is still retained within.

[E Sully]

Not sure if it applies to you, but Warren,Early_S_Man, but he has a few comments about the regulator and suppressor. He states a bad suppressor(capacitor) can cause issues. In Post 3 he shows the higher output alternator that I believe was original in the 3.0 Carrera.
SEV Marchal- OEM for 74?
Also Alternator or battery issue?

[T77911S]

the problem is at the instrument cluster or about.

one side of the alt light is connected to the batt, the other is D+. if the batt and D+ are the same volatge, as in the alt is charging the batt, then the light is off. if they are different, the light is on.

it sounds like the batt side is not connected and the alt is more or less charging thu the alt light. this would explain the strange gauge operation.
check the red/bk wire to the battery and the blue wire to the alt/reg.

[jsveb]

Originally Posted by E Sully

Not sure if it applies to you, but Warren,Early_S_Man, but he has a few comments about the regulator and suppressor. He states a bad suppressor(capacitor) can cause issues. In Post 3 he shows the higher output alternator that I believe was original in the 3.0 Carrera.
SEV Marchal- OEM for 74?
Also Alternator or battery issue?

Tanks for those links, very good information.

I do not believe I have that suppressor on my car.

My alternator is a 70 amp unit.

[jsveb]

Originally Posted by T77911S

the problem is at the instrument cluster or about.

one side of the alt light is connected to the batt, the other is D+. if the batt and D+ are the same volatge, as in the alt is charging the batt, then the light is off. if they are different, the light is on.

it sounds like the batt side is not connected and the alt is more or less charging thu the alt light. this would explain the strange gauge operation.
check the red/bk wire to the battery and the blue wire to the alt/reg.

In Danish voltage is termed "(electrical) tension differential" which makes the charge indicator light make sense. No differential no light

I will try and check the wires as you mention.

Thanks

[jsveb]

T77911S,

I have been checking the two wires, blu and redblk.

Confirm there should not be continuity between the blu and ground when measuring the blue wire on the fourteen pin male chassis plug (#11)? I'd think NO

Well, when I measure for continuity, it sure seems to be grounded out, the blue wire that is, but when I then disconnect the blue wire from the oil light, the continuity is gone. This means the error is in the redblk wires, doesn't it?

Also in my trouble shooting I found that the instrument light does not work on the speedo and the clock, maybe related?

I'll go out and work on it some more, just wanted to post while I remembered it all



EDIT: when I turn on the ignition, the ground continuity goes away, maybe it is the way it is supposed to be.

[Srwilliams]

Originally Posted by jsveb

T77911S,

I have been checking the two wires, blu and redblk.

Confirm there should not be continuity between the blu and ground when measuring the blue wire on the fourteen pin male chassis plug (#11)? I'd think NO

Well, when I measure for continuity, it sure seems to be grounded out, the blue wire that is, but when I then disconnect the blue wire from the oil light, the continuity is gone. This means the error is in the redblk wires, doesn't it?

Also in my trouble shooting I found that the instrument light does not work on the speedo and the clock, maybe related?

I'll go out and work on it some more, just wanted to post while I remembered it all



EDIT: when I turn on the ignition, the ground continuity goes away, maybe it is the way it is supposed to be.

Guys can I jump in on this as I too do not have battery power going to my alternator. As my engine runs my battery runs down. I have an 87 Carrera.

I had my battery and voltage regulator checked twice and they checked out well in both instances. In fact, I had them rebuilt.

My problem probably centers on work I did at the instrument panel or console. I put a push button start in my car. Maybe I did not hook up the wires between the battery and alternator, if there are any. Simply stated from a novice standpoint, my alternator is not linked to my battery, so it seems. I hope you guys can make some sense out of what i am saying because I know I am speaking nonsensical.

In this thread everyone is talking about the red/black and blue wires. WHERE ARE THOSE WIRES LOCATED AND Is there a way to trace those wires to see if they are connected correctly. I know the alternator wires are conected correctly because I followed the pictures in this forum and connected them three different times. My problem lies elsewhere..

I have been reading all of the posts on this forum dealing with alternator wiring and some guys talked about the Alternator bulb, check for proper function when back in the circuit and check voltages AFTER the battery has been charged by an outside source. I think I took that out of circuit or failed to reconnect. Perhaps I should look in that area.
Any assistance will be greatly appreciated