I’ve been driving my car all over for the past week or so.
Last weekend I noted that it was hard to start, and it stalled while pulling away in 1st once. Weird. Didn’t worry about it and finished my drive.

Got home and I checked voltage at the battery and I was making 18 volts, my VR had seemed to fail and I was pushing max voltage at the battery. Geeze, no wonder the car was hard to start with the alternator at max effort.

So, I’ve done the ground thing and they are all clean and good. In my undercharging thread I ran a 10ga wire from the alternator case to the body ground point near the relay board in the engine bay.

I’ve also checked all my collection of voltage regulators and all 5 of them, be they mechanical or solid state are now allowing the alternator to go full bore all the time.

This is with both the brand new battery and the PC680 gell cell race battery.

What do I look for now? Could I have broken the VRs by pulling them off the running car while chasing issues with the alternator last time? Or is this a car thing and I need to fix something else.

The car is essentially acting like I have D+ and DF jumped with D- left empty.

Zach

Did you find a 666 tattooed somewhere on your car?

If you pull the VR (with the engine off), does the alternator quit charging?

Yes. Pull the VR and the idle picks up and the battery quickly dips down to about 12.8 volts.

Zach

I wasn't aware the could achieve 18volts I was always thinking they topped out @ 16volts ,your altenator must be heathy,have you checked for continuity across D+ and DF on your regulators ? could you have a dead short across those pins on your relay board maybe? its unlikely you could have 5 bad regulators but who knows,have you tried a new one?.
Hopefully you haven't damaged your batteries,I had a charger that killed one of my batteries....boiled the snot out of it .
Good luck sorting this .

If want me to test the VRs, I'll check them out on my car. It would be strange that 5 VRs are bad but who knows.

@spoke
Send me your address and I’ll send a VR care package.

I suspect it’s not really the VR, but would be good to cross that off the list.

Is it possible that by grounding the alt case directly to the chassis I have done an end run around something which is causing this issue?

Zach

Isn't an alt case already grounded to the chassis via the normal mounting bolts ???

Grounding the alt case to the chassis should not cause an issue. The normal alt case grounding goes from the alt case >> Fan shroud >> engine case >> transmission >> trans strap >> chassis.

You have the alt case strapped directly to the chassis. Either way should be milliohms and should not be an issue. If you want to feel better about it, use a very short cable and ground the alt case to the engine case.

PM sent with my contact info. If you ship USPS flat rate small box it'll cost about $7 and I can get it this weekend and test. I'll just put them in my 914 and see what happens. My current VR/alt gives a rock solid 14.0V from idle to max RPM.

What about your alternator warning light? Sorry I didn't go back and read all the old thread

Yes, that's the theory. The alt case is grounded via:

alt case >> Fan shroud >> engine case >> transmission >> trans strap >> chassis.

In Zach's car the fan shroud and alt hanger were powder coated which caused probably only 0.5 ohm of resistance or less. 1/2 ohm doesn't sound like much but for example run 2 amps through 0.5 ohm and it drops 1V.

The VR should hold the alt voltage to 14V so losing 1V means 13V at the battery. Turn on the headlights and the draw goes to 5-10A and the battery discharges while driving.

Depends on the VR used.

For the solid state VRs the light will remain lit until the engine revs to about 1000 RPM and then go out, so it stays on for about 1/2 second on start up.

for the mechanical VRs the light goes out as soon as the car turns on.

In all cases the light does go out, which makes sense as the car is in fact charging. Just too much at this point.

Zach

What you are seeing with the GEN light is normal. The 1/2 second start up is the time it takes for the VR/alt to bootstrap itself and start running normally.

Take off your relay board and take a look at the bottom. On my previous car the board had been repaired after the insulation failed and the repair material was slightly conductive, leading to exactly the same issue you have with overcharging. Good luck!

Just put a new relay board in it a few weeks ago while trying to find the cause of the undercharging issues.

Part of the reason why this is frustrating is that I have replaced or cleaned every part of the charging system over the past month.
*new alternator
*new alternator harness
*new relay board
*several new voltage regulars
*cleaned all the engine compartment grounds, and added a heavy ground from alternator case to the chassis.


Zach

Keep in mind that you have made progress. Instead of under-charging the system can now charge correctly. Why the VRs aren't behaving is unknown at this time.

It's like you've moved the goal posts closer by 10 yards and moved the kicker back by 5 yards. Keep the faith; you'll figure it out eventually.

I've been reading online that voltage regulators can be killed by voltage spikes. So there is decent chance that I just plain old killed them by swapping them out so much while testing the car over the past month, seeing as how the car was running when I'd pull the VR to short DF to D+. Or swapping the VRs areound when I thought the issue may have been with the VR before I ran the ground wire.

I was mean to them.

Zach

What brand voltage regulators are you using? I had purchased a new Beru brand VR for my 6 and killed it in 80 miles.. was charging at 16.8V. Being 2 hours from home I stopped at auto zone and they had a duralast regulator in stock. Part number VR650. It has worked flawlessly for the last 3 or 4 years.

I've installed these in 3 other 914s and have been extremely pleased with them. Nice stable voltage, and they're cheap and easy to get your hands on.

Mixed bag of brands, but I don't know that any were Auto Zone Duralasts. AutoZone is my local FLAPS so I may run over after work to see if they have one. I think the same company makes the house brand stuff for AutoZone and all the other big chains, and there is a NAPA and the other Red and Yellow store across the street, so I'll check there too.

Zach

Electrically, the only way this could happen is if the VR is allowing for max voltage at DF which then caused the alternator to juice out max amps. Something that would cause this would be a ground in the feed to the VR indicating that the system was in need (maximum need). But your bulb is working and it couldnt if there was a ground. This happened after a new board? Did I understand that correctly?

I always thought that when VR fried they went to low volts on the DF?

Yes, new relay board. Well, old, but with excellent potting.

Zach

are the plug terminals from the alternator harness into the board misplaced??

Worth checking. I've done this and the results weren't good.

I've had one of these in my 914 for several years. Dead nuts on 14.0V over the entire RPM range.

It makes more sense to challenge the vr with steadily varied alternator input and following conductance to the charging circuit. When I went through this headache I used an adjustable voltage power supply in lieu of the alternator to bench test the regulator. That was when I found a group of VRs that weren’t set to what I considered the right voltage. I could send you some with known set points.

Which means you don’t have a Df to D+ short at any place outside the VR. One of the most frustrating problems I ever encountered was when a new ignition component was dead right out of the box. I usually assume they start out goog. I had a set of new points fail in only ten miles. Drives you nuts.

You can double check this by plugging the VR directly into the harness from the alternator. If I recall right, the alternator harness plug that goes to the relay board is the same shape as the plug from relay board to VR.

and


I missed the part where you were doing the changes to the system with the engine running. It is generally very risky to make changes to the charging system while in operation. Always make changes with engine off. Not saying this could cause an issue but it doesn't help and something could be damaged.

Yes, the VR should plug into the alt connector. The only other connection needed is to D+ on the relay board to get the GEN light involved else the alternator may not bootstrap itself.

I just ordered a new VR.
Jerry, I never mailed the regulators I have to you. I think I just killed them.

If the new one does not work i'll post up to this thread. But this feels like its the VR not doing its job, and I probably killed my other ones either from the grounding issues or from testing while the car was running.

Zach

Good luck with the new VR. When you fixed the ground loop issue, I thought it better to wait a week or 2 before declaring problem solved. Then you started this thread and damn if the charging system still isn't working right. Lets hope the NEXT VR will finally solve the charging issues.

Alternator connections:
D+, DF,D-, and B+.

D- terminal - Alternator housing ground. Is also the ground return from the VR.

Diodes:
D+ terminal -low output. Secondary output of alternator.
B+ terminal - high current. (also direct to battery)
Diodes on path 80 is common to both the D+ and B+.
This also links the ground loop for D+, B+ out.

If the diode out circuit faults at B+ voltage will fall at the high output side.
If the D+ diode faults voltage will fall on the low output side.

Charge lamp:
D+ connected to charge warning lamp and ignition switch, voltage sourced from battery.

This is fused at #9. Charge lamp bulb should be 2 watts. Less than 2 watts will not excitate the field properly. For troubleshooting purposes the VR cannot determine voltage at both diode circuits. The VR is primary to the low output on D+. Any low voltage difference between B+ and D+ will keep the charge light on.

The charge lamp will have 12V current on the switched side and ground from the field. Boot strapping is managed through the charge warning lap and ignition switch at D+ as the alternator cannot excitate on its own.

Starting and Running:
Upon engine starting no output from the B+ or D+ terminals should be available. The VR closes D+ and DF. D+ drops to low resistance via field.
Working properly the alternator spins and creates a field which generates voltage at D+ and B+ that are the same then the warning lamp will turn off.

Running

Voltage regulator:
D+ voltage should be what you are seeing at the battery. As the ground drops away (charge lamps goes off) D+ and DF are now regulated.

I believe you already tried the regulator removed from the board and connected direct to the alternator connector. If no changes move on. To me this rules out both the regulator and board.

If you remove the VR while the engine is running the charge light should stay off as the voltage is still balanced at the diodes at D+ and B+.

Relay board:
Jumper 12V volts from the battery to the DF terminal at the board? This will let the alternator juice out to its highest possible output running. This will also confirm the diodes at B+ and windings are good

Alternator:
How are you checking the maximum output of the D+ circuit? This will be your charge supply to > the battery. Jumper D+ and DF on the board. Don't measure the voltage supply at the battery as you will have a false reading. Has to be measured before as close to the alternator as possible, then at the board but not past the board. This should show the maximum output of the alternator output on the D+ circuit.

Disconnect the jumper at D+ and DF. Running measure the readings again on the board at D+. Read the battery. They should be the same. If the voltage is high you most likely dropped a diode on the low output side and D+ is feeding back through the high voltage side of B+. This can appear as a ground loop problem when its actually the low side diode.

The charge light will turn off as its still getting voltage from both sides on D+ and B+ once the excitation starts through feedback trying to balance out.

I believe you a have a few things going on.

1) What wattage bulb is in the charge light? Did you install an LED or new bulb at some time? Should be 2 watts or less incandescent. If it's an LED go back to the incandescent as it acts as a resistor.

2) Double triple check the board. A short in or between D+ and DF will put the output voltage into boil your battery territory.

3) Double triple check the new harness. Make sure no two reversed wires. (Unlikely based on symptoms but worth checking again).

4) Ignition switch: Check from ignition switched power to the #9 fuse, fuse box terminals, wiring to the charge lamp circuit and back to the alternator lead connection.

5) Alternator - D+ side diode toast. Pull it and get it bench tested by an alternator/starter shop. If the alternator is good it will point you backwards towards a ground issue. (are you sure you corrected the ground issue in your undercharging adventure? Was it an actual ground issue or something undiscovered and still present?)

I can't see this many VR's all being bad. VR's are pretty durable considering the cycles they go through. One of the above may be killing them as a side effect.

Good luck Zach.

Thanks Jeff I’m going to need to read this a few times before I understand it all.

I am fairly certain I found the grounding issue from earlier, based on measuring voltage from D- and chassis ground and going from 1.7 lost volts to milivolts after adding the ground strap.

The GEN lamp is the stock lamp. No LED there.

I’ve not touched the ignition switch and may dive into this.
Zach

I installed the new VR today and it made no difference.
Voltage on startup went right to 17 volts.

Back to the drawing board. Two days till the car show I want to take the 914 to.

Zach

got to be relay board or alternator..I might have an extra..

so you did verify the wiring sequence into the relay board and made sure that none of the three receptacles was backed back?

Zach,

Measure the voltage at each of the VR terminals to chassis ground. Try to be quick and don't rev the engine to keep stresses down.

I'm assuming the GEN light is on when key is on and engine off, then goes off when engine is started.

There seems to be some wiring issue still at large. The system is quite simple and shouldn't be this difficult to get working correctly.

Or arrange for an exorcism. This has gotta be super frustrating. Please keep us up to date about what you discover.

+1 on checking the relay board. Also, make sure the female connectors aren't pushing out the bottom of the board when you install the voltage regulator.

I had a problem with my 914 overcharging the battery a couple of years ago, and it turned out the relay board was bad. Got a rebuilt board from Brad M., and haven't had a problem since.

Uggggggghhhhhh. :-(

Mom was readmitted to the hospital last night. No playing with the car was done, aside from plugging in the new VR and getting the same overcharge reading on the multi-meter. Tonight is running kids around or running to the hospital. Maybe I'll get a chance to work on it tomorrow at lunch, if I'm not booking it down to Baltimore to get to the hospital again.

This car is so close, I hate it taking a back seat to life issues. But in the end its just a car. There is always the October show at the Amish markets. Tomorrow is still a possibility, but becoming a distant one.

Zach

I hope your Mom recovers quickly. I wonder if you'll find your electrical gremlin before I find my cooling gremlin? I'm going to let my beard grow until I capture my gremlin. Stay after it. I am.

Holy crap I think I just found it!

Click to view attachment
FOUND IT!

The D- pin that the VR plugs into had pushed through the potting on the replacement board I got from Mark E. I was reaching around trying to feel for the chassis ground under the relay board when it poked me.

So now I have 2 relay boards I need to restore. Lol. At least I found it!

Zach

Glad to hear.

Nice! now you can make that show

And you didn't have to call in a priest!

that's awesome!- I have been watching this closely with interest to see what it would be, looks like Doc and Jeff were both on the right track, in Jeff's previous post in item #2 he stated, double-triple check the board and its connections ! and their it was! I HATE electrical stuff but we make it more complicated than it is sometimes,- so Now you can go to the event I hope!! - Hope your mother is doing better so that you can as well.

Phil

Yup. I assumed that just because the board was solid when I put it in last month, there was no way it could be the board now. I was chasing my tail over a 30 second fix. I was going to spend my lunch doing the tests the Jeff and Jerry prescribed, and found it while reaching around for the ground stud.

My brain literally went "no F*(KING way!"

Zach

I know the feeling! I did the same thing trying to get my car started after reassembly 2 weeks ago, and it ended up being the fuel pump ground! after 3 hours trouble shooting my connections and board!! BUT I learned a lot from that so it was super stressful but a great learning experience - I now know how to trouble shoot the whole board and all the relays and their connections - thanks to instructions from Jeff Bowlsby. ( however my mind thinks differently and when I have time I am going to rewrite those in an order that makes more sense to me, like not taking this plug and that plug out over and over again back and forth!)

Do you have a good board?? there was a guy here last year that sold some brand new boards he made, cant remember the name, but now I wish I had bought one!

Mine will work fine for the rest of the fall. I have 2 that need to be repotted, planning to do it with epoxy. One of them is already cleaned and ready for the repotting.

Zach

Everybody has done stuff like that. If anyone hasn't, they will...

A memorable one for me was troubleshooting a no-start for two hours and then noticing I had bumped the CHT sensor connector and disconnected it....

--DD