The alternator replacement thread, Fixed! Options

[VaccaRabite]

I can't remember...

Is your alternator harness new?
Battery positive cable?
Battery?

You can also attach the VR directly to the alternator harness, bypassing the relay board, BUT you'll have to add a jumper wire to bootstrap the alt and make it charge.

Another aspect is that a dead/dying battery won't take a full charge, and that can look like charging issues.

Oh and I have the distinct impression your car has a curse on the electrical system.

New Alt. New Alternator harness. New VR.
Battery is the Odyssey race battery that came from your shop last year. No telling how old it is.

And my car decidedly has some sort of gremlins. I'm slowly eliminating them.

Zach

[jarodswordmaster]

I can't remember...

Is your alternator harness new?
Battery positive cable?
Battery?

You can also attach the VR directly to the alternator harness, bypassing the relay board, BUT you'll have to add a jumper wire to bootstrap the alt and make it charge.

Another aspect is that a dead/dying battery won't take a full charge, and that can look like charging issues.

Oh and I have the distinct impression your car has a curse on the electrical system.

New Alt. New Alternator harness. New VR.
Battery is the Odyssey race battery that came from your shop last year. No telling how old it is.

And my car decidedly has some sort of gremlins. I'm slowly eliminating them.

Zach

Where have you gotten with this now? Did you find the culprit. I'm going through the same scenario and don't feel like spending what I don't need to spend for parts that are okay.

[VaccaRabite]

I can't remember...

Is your alternator harness new?
Battery positive cable?
Battery?

You can also attach the VR directly to the alternator harness, bypassing the relay board, BUT you'll have to add a jumper wire to bootstrap the alt and make it charge.

Another aspect is that a dead/dying battery won't take a full charge, and that can look like charging issues.

Oh and I have the distinct impression your car has a curse on the electrical system.

New Alt. New Alternator harness. New VR.
Battery is the Odyssey race battery that came from your shop last year. No telling how old it is.

And my car decidedly has some sort of gremlins. I'm slowly eliminating them.

Zach

Where have you gotten with this now? Did you find the culprit. I'm going through the same scenario and don't feel like spending what I don't need to spend for parts that are okay.

Not yet.

I've been going through grounds as I am able, but life got a bit busy and my allergies have been HORRIBLE the past couple weeks. Hot and humid or pouring and walking around with my head in a fog. Ugh.

However, I'm currently showing 0 ohms resistance from alt to body and engine to body. Which seems to eliminate grounding as being the issue.

Friday I'm going to buy a new battery. I've replaced or cleaned everything else.

Zach

[VaccaRabite]

I got a new battery.
Not really any change over the smaller race battery.
So I started playing with the collection of VRs I have recently collected.
Depending on what VR I used, at idle I was seeing a range from 12.3 volts to 13.6 volts. The best results were from a hella solid state VR and an unamed adjustable solid state VR.

With headlights and driving lights on, I’m showing 12.5 at the battery with the better VRs at hot idle.

The voltage still drops when the engine revs, and sits at about 12.3-12.5 volts at 4K.

If I short DF and D+ voltage DOES rise with rpms, and quickly goes up to 17-18volts.

I have gone through all my grounds and currently see 0.000 ohms resistance anywhere. No resistance between engine case and negative battery terminal. None between alternator and engine or alt and body.

My measurements from the battery and the voltmeter on the ECU are different by a volt (ECU sees slightly less voltage then the battery is showing).
I’m left thinking this is just how my car is, and I DO NOT like it. I’m totally stumped, and have run out of things to replace. I think my car is probably fine to drive during the day, but I am afraid to drive it anywhere at night.
Help?

@spoke
@clayperrine
@mcmark

PS. I just reread Spoke’s last post and still need to measure voltage between D- and the body. I’ll do that tonight. Now I’m off to the hospital to give comfort to mom.

Zach

[rjames]

Watching this thread rabidly as my charging system is exhibiting similar behaviors.

[worn]

I got a new battery.
Not really any change over the smaller race battery.
So I started playing with the collection of VRs I have recently collected.
Depending on what VR I used, at idle I was seeing a range from 12.3 volts to 13.6 volts. The best results were from a hella solid state VR and an unamed adjustable solid state VR.

With headlights and driving lights on, I’m showing 12.5 at the battery with the better VRs at hot idle.

The voltage still drops when the engine revs, and sits at about 12.3-12.5 volts at 4K.

If I short DF and D+ voltage DOES rise with rpms, and quickly goes up to 17-18volts.

I have gone through all my grounds and currently see 0.000 ohms resistance anywhere. No resistance between engine case and negative battery terminal. None between alternator and engine or alt and body.

My measurements from the battery and the voltmeter on the ECU are different by a volt (ECU sees slightly less voltage then the battery is showing).
I’m left thinking this is just how my car is, and I DO NOT like it. I’m totally stumped, and have run out of things to replace. I think my car is probably fine to drive during the day, but I am afraid to drive it anywhere at night.
Help?

@spoke
@clayperrine
@mcmark

PS. I just reread Spoke’s last post and still need to measure voltage between D- and the body. I’ll do that tonight. Now I’m off to the hospital to give comfort to mom.

Zach

After a lot of trying along similar lines I bought about six different voltage regulators and found that they pretty much all tended to undercharge. Especially with lights on. I ended up purchasing an adjustable regulator and that solved the problem. Now I have several extra alternators and other electrical system parts that I swapped out along the way. Can’t tell you how nice it is to be able to turn the switch and see about 13 and a half volts going in, plus or minus a bit. My regulator came from a site oriented towards Volvo 1800s.
Hope it works for you soon.

[FourBlades]

Does the charging problem only happen when the lights are on?

What is the resistance of your lighting circuit?

If it is way low, could it act like a partial short?

Man, I hate chasing electrical gremlins, I feel for you!

John

[jarodswordmaster]

I can't get any charge out of my alternator with any of the tests so I"m assuming the alternator needs to be replaced.

[Spoke]

I got a new battery.
Not really any change over the smaller race battery.
So I started playing with the collection of VRs I have recently collected.
Depending on what VR I used, at idle I was seeing a range from 12.3 volts to 13.6 volts. The best results were from a hella solid state VR and an unamed adjustable solid state VR.

With headlights and driving lights on, I’m showing 12.5 at the battery with the better VRs at hot idle.

The voltage still drops when the engine revs, and sits at about 12.3-12.5 volts at 4K.

If I short DF and D+ voltage DOES rise with rpms, and quickly goes up to 17-18volts.

I have gone through all my grounds and currently see 0.000 ohms resistance anywhere. No resistance between engine case and negative battery terminal. None between alternator and engine or alt and body.

My measurements from the battery and the voltmeter on the ECU are different by a volt (ECU sees slightly less voltage then the battery is showing).
I’m left thinking this is just how my car is, and I DO NOT like it. I’m totally stumped, and have run out of things to replace. I think my car is probably fine to drive during the day, but I am afraid to drive it anywhere at night.
Help?

@spoke
@clayperrine
@mcmark

PS. I just reread Spoke’s last post and still need to measure voltage between D- and the body. I’ll do that tonight. Now I’m off to the hospital to give comfort to mom.

Zach

About the voltage measurement from D- to chassis, connect the negative lead to the chassis post beside the relay board. You should read 0.0V since the alternator case is bolted to the fan shroud which is bolted to the engine case which is bolted to the transmission which is strapped to the chassis post under the trunk. All should be 0.0 ohm connections. The strap does have finite resistance which is proportional to its length; maybe 10 mOhm.

A loss of even 1V with the ground will greatly affect the charging circuit. I doubt this is an issue but we've got to cross off all variables. With the charging problems you've been having, something in the charging system is definitely wrong. You haven't found it yet. It shouldn't be the battery, alternator, or VR since you've changed all these items and the system still isn't right.

Which VR gave 13.6V at idle? Seems that VR is the best candidate seeing that you can get high voltages when DF is shorted to D+.

With DF shorted to D+, do you see the same drooping of voltage when revving the engine?

Which VR gave the drooping voltage you quoted?

[Spoke]

I can't get any charge out of my alternator with any of the tests so I"m assuming the alternator needs to be replaced.

Is the GEN light on when the engine is running?

What voltage do you read on the battery with DF shorted to D+?

[jarodswordmaster]

I can't get any charge out of my alternator with any of the tests so I"m assuming the alternator needs to be replaced.

Is the GEN light on when the engine is running?

What voltage do you read on the battery with DF shorted to D+?

Yes, the gen light is on when the engine is running, same volts running and not running, 12.6. when I short DF to D+ I get no change in the voltage. I'll run through all the tests again today. I short DF to D+ with all connections still made between the alternator, relay board and VR correct?

[Spoke]

I can't get any charge out of my alternator with any of the tests so I"m assuming the alternator needs to be replaced.

Is the GEN light on when the engine is running?

What voltage do you read on the battery with DF shorted to D+?

Yes, the gen light is on when the engine is running, same volts running and not running, 12.6. when I short DF to D+ I get no change in the voltage. I'll run through all the tests again today. I short DF to D+ with all connections still made between the alternator, relay board and VR correct?

Remove the VR then short D+ to DF. Measure the voltage from DF/D+ to chassis. Should be the same as the battery voltage. If not, the alternator is suspect.

When did this change from working correctly to not working correctly? Did you check the alternator belt for tightness?

[jarodswordmaster]

I can't get any charge out of my alternator with any of the tests so I"m assuming the alternator needs to be replaced.

Is the GEN light on when the engine is running?

What voltage do you read on the battery with DF shorted to D+?

Yes, the gen light is on when the engine is running, same volts running and not running, 12.6. when I short DF to D+ I get no change in the voltage. I'll run through all the tests again today. I short DF to D+ with all connections still made between the alternator, relay board and VR correct?

Remove the VR then short D+ to DF. Measure the voltage from DF/D+ to chassis. Should be the same as the battery voltage. If not, the alternator is suspect.

When did this change from working correctly to not working correctly? Did you check the alternator belt for tightness?

my son and i are working on reassmbling a rust bucket that everything had been gutted except for the wiring harness to strip for painting. So, this alternator hasn't been proven out to get good yet. I don't recall if it was the one I had on this engine 4 years ago when I pulled it from the 72 we sold. It's all a blurr now as to what I swapped when I put the 1.7l back in the 72 and sold it. I kept the 2.0l and side shifter for the 76 it belongs to that we are working on now. I'm pretty sure I have the circuit complete for charging. Just want to make sure before spending money on the wrong part.

[VaccaRabite]

I’m back to grounds.
And I’m going to put a new battery in my multimeter, as it’s lying to me somehow on Ohms. It’s gotta be.
Just did the DF shorted to D+ test, measuring voltage from D- to chassis. I picked 2 spots to measure. Both showed a voltage of (drumroll please...)

1.6 volts.

Yesterday, and today, I was showing zero resistance between any points on the car. But I have a voltage drop of about 1.7 volts. It danced around a little bit settled between 1.6 and 1.7.

Something is resisting somewhere.

This would also probably match with the voltage difference in seeing when I measure the battery and what the ECU says it’s seeing on my testing laptop, as the ECU is seeing less.

Another curious note. The red Gen light comes on at key in, goes off when the engine starts, and stays off when I pull the VR out of its slot. Should it do that, or should it light up again to alert me that something is not charging?

Zach

[Spoke]

I’m back to grounds.
And I’m going to put a new battery in my multimeter, as it’s lying to me somehow on Ohms. It’s gotta be.
Just did the DF shorted to D+ test, measuring voltage from D- to chassis. I picked 2 spots to measure. Both showed a voltage of (drumroll please...)

1.6 volts.

Yesterday, and today, I was showing zero resistance between any points on the car. But I have a voltage drop of about 1.7 volts. It danced around a little bit settled between 1.6 and 1.7.

Something is resisting somewhere.

This would also probably match with the voltage difference in seeing when I measure the battery and what the ECU says it’s seeing on my testing laptop, as the ECU is seeing less.

Another curious note. The red Gen light comes on at key in, goes off when the engine starts, and stays off when I pull the VR out of its slot. Should it do that, or should it light up again to alert me that something is not charging?

Zach

The GEN light staying off when the VR is out is expected. The 2nd set of diodes in the alternator generates a voltage equal to the battery voltage.

About the 1.6V, try running a wire from the generator body to the engine case.

[VaccaRabite]

Goddamn happy dance.
14 volts at idle.
14 volts at 4K rpm.
Using either of the single piece solid state VRs. Using the pig tailed solid state VR showed 13.5v. And the mechanical VR I got from Bruce was dancing from 13.5 to 14V.

It was a grounding issue. I went back through the grounds, recleaned them, and added a 10 gauge wire from the alternator case to the chassis ground under the relay board. (I was doing that as you posted Spoke).

Damn, that was a tough one. Still don’t know why the grounding issue was happening, as the meter said I was golden. But, clearly, the meter was wrong.

Zach

[VaccaRabite]

I’m going to put the race battery back in and check that. I suspect it will be fine, and I’d like to use this battery on another vehicle that needs a battery. So the Toyota will, again, steal a battery from the 914, and the Toyota battery will be the core battery that goes back to FLAPS.

ZACH

[Spoke]

Goddamn happy dance.
14 volts at idle.
14 volts at 4K rpm.

Awesome! (IMG:style_emoticons/default/beerchug.gif)

[ClayPerrine]

Goddamn happy dance.
14 volts at idle.
14 volts at 4K rpm.
Using either of the single piece solid state VRs. Using the pig tailed solid state VR showed 13.5v. And the mechanical VR I got from Bruce was dancing from 13.5 to 14V.

It was a grounding issue. I went back through the grounds, recleaned them, and added a 10 gauge wire from the alternator case to the chassis ground under the relay board. (I was doing that as you posted Spoke).

Damn, that was a tough one. Still don’t know why the grounding issue was happening, as the meter said I was golden. But, clearly, the meter was wrong.

Zach

That's great!!!

I never really thought about it before, but adding a heavy brown wire to the alternator harness and running it back to the ground point at the relay board is a really good idea. (IMG:style_emoticons/default/idea.gif)

[bdstone914]

Zach,

Are your alternator mounting brackets painted of plated ? I have heard that painted brackets interfere with the grounding.
Is that using the alternator and VR I sold you?
Bruce


@vaccarabite