Autometer Gauges Flashing When Taurus Fan Comes On - Alternator?

[73azbronco]

Those are Jeep guys, I wouldn't put much faith in anything that they do.

Ouch, I'm hurt

 

[jamesroney]

Thank you for the info. I agree that the Summit Gage reads about 8% off, or 1V at ~14V. Its always low but appears consistent. So when it says 13.5, it means 14.5.

The original problem in post #1 was "when I drive, it reads 13V." Which we now know to mean 14V. So go ahead and drive it around the block, get it warm, and get the fans running...and when you see it indicate 13V...turn on the headlights, (high beam) and everything else you have. Then see if it continues to decay...or if it's happy sitting at 14V. (indicating 13V)

That will tell you if your fans are sitting on the edge of your charging capacity.

The fact that you are sensing your battery voltage at the alternator output lug is problematic when you have high currents. But that's the way 1 wire alternators work. There might be a benefit to adding an additional #12 sense wire from your alternator post to your battery post. But I'm not an EE.

 

[DanWheeler]

Thank you for the info. I agree that the Summit Gage reads about 8% off, or 1V at ~14V. Its always low but appears consistent. So when it says 13.5, it means 14.5.

The original problem in post #1 was "when I drive, it reads 13V." Which we now know to mean 14V. So go ahead and drive it around the block, get it warm, and get the fans running...and when you see it indicate 13V...turn on the headlights, (high beam) and everything else you have. Then see if it continues to decay...or if it's happy sitting at 14V. (indicating 13V)

That will tell you if your fans are sitting on the edge of your charging capacity.

Correct, and I’d say the Summit Racing volt meter is really only off by 1/2 a volt from what I can tell.

Btw - yes, looks like I did your tests wrong after re-reading your instructions. But I think it still kind of ruled out a ground issue. There’s definitely some resistance between the battery post, my in-cab fuse box, the relay for the ignition switched circuits, the sub fuse panel for the ignition switched circuits, my weatherpak connectors to the sub-dash and then the return path through the ground screw, chassis, chassis connection to the block and block to the negative battery post. It’s got a long path to go, I’m surprised it’s only losing 1/2 a volt.

Anyway, so when the Summit Racing voltmeter dips down to 13.1 or 13.0 (which should be 13.5 at the battery) with the fans running, that’s when the gauges get weird and I turn around and come home because something seems off like it’s not charging and I live in the sticks and have no friends to rescue me if I break down.

There’s no other issues besides the gauges. I have not actually been stranded yet or had any weird EFI issues running at the lower voltage. I just haven't had the balls to keep driving around after it drops to 13.0 or 12.9 to find out if it keeps dropping. It is stable at 13.2 at idle in my driveway. It’s not until I get out on the road that I start sweating about the voltage dropping. It’s like watching your engine temperature slowly creeping up but in reverse. You know it’s not going well.

 

[ntsqd]

The clicking issue aside my next step would be to put an OEM regulator in the existing alternator and wire it how Ford wired it. Then see if you still have this same problem. If the clicking is the brushes then a whole regulator replacement may fix that too.

Why I'm resistant to the higher output alternator is that my experience and observation has been that they cost a lot more and do not last as long as the stock output alternators. The main reason is easy to see, making power generates heat. Make more power and you generate more heat. More heat without an increased ability to remove it shortens the life of the alternator. The best way to shed more heat is to go to a larger alternator case. The aftermarket only seems to care about output, not longevity. I always look for the highest output OEM alternator in whatever alternator case I'm dealt with. Ford has warranty obligations to consider when designing the charging system, so they are going to arrive at the best compromise of output and longevity (& cost). If I need more power than I can find OEM in a particular alternator series I first look for a larger case alternator series that can be easily swapped in. If that's not possible, then I'll look at aftermarket higher output units. In doing that I know that I'm trading life-span for output so I try to find the output version that is the closest to my max needs. If a 130A is barely not getting it done it could be that a 150A unit is all that is needed.

 

[DirtDonk]

Mine is internally regulated, yes, and has a single wire coming from the top post to the rest of the system.

Yep, they are all like that. Whether standard three wire, or aftermarket one wire, there is a single heavy charge wire coming from that terminal over to the battery or starter relay or distribution block. That large charge cable does not determine the type of alternator.
You have what looks to be a 4G Explorer model.
But yours has what looks to have at least 3 wires. Maybe even 4, in the regulator connector.
Is that also correct?
Was the regulator converted to a self-exciting model (one-wire) and you simply reused the original connector?
Or is this not an explorer front drive set up, but instead a Mustang or other? Maybe with a 3G side mount alternator?

The trigger wire is jumpered to the top post so it tells it to turn on when the alternator starts spinning.

That’s not a trigger wire. And it can’t trigger from that location anyway, because the large cable always has battery power on it already.
The yellow wire doesn’t trigger anything.
Whether you have a one wire, or three wire, it’s still a sensing wire.
And it looks really wonky all bent around at 180° like that. unless that’s just the angle of the camera?
Are you certain in good shape and not building up some resistance? Although, now that I think about it, if it was building up resistance and reading low, the alternator would theoretically put out more power. Not less.

I really thought that's what everyone was doing these days.

Not everyone. But plenty of people prefer a one wire over a three wire for simple simplicity.
But in your main connector, it looks like the trigger/excite wire is still there. Is that connected to anything or are you just using an old standard connector with the wires still intact?
If so, are there two wires, or three wires in that connector?
The sensing wire is yellow with a white stripe and is the one running there to the battery charge terminal on the back of the alternator. As James mentioned, though, it would be better to run it closer to the battery instead. Which is how Ford originally did it.
But plenty of people do as yours is set up, and they seem to work. Maybe yours is suffering a little bit of that inefficiency however.

An earlier 3G alternator uses the same connector, but with three wires instead of the two that an Explorer 4G would have.
A 3G connector has a white with black striped wire and the third wire would be a green with a red stripe.
That Green w/red wire is the trigger/excite wire and is switched 12v from the ignition switch. But is unused in a one wire configuration.
Have you pulled that connector out and measured voltage on the two wires? Both key on, and key off?

 

[jamesroney]

Correct, and I’d say the Summit Racing volt meter is really only off by 1/2 a volt from what I can tell.

Btw - yes, looks like I did your tests wrong after re-reading your instructions. But I think it still kind of ruled out a ground issue. There’s definitely some resistance between the battery post, my in-cab fuse box, the relay for the ignition switched circuits, the sub fuse panel for the ignition switched circuits, my weatherpak connectors to the sub-dash and then the return path through the ground screw, chassis, chassis connection to the block and block to the negative battery post. It’s got a long path to go, I’m surprised it’s only losing 1/2 a volt.

Anyway, so when the Summit Racing voltmeter dips down to 13.1 or 13.0 (which should be 13.5 at the battery) with the fans running, that’s when the gauges get weird and I turn around and come home because something seems off like it’s not charging and I live in the sticks and have no friends to rescue me if I break down.

There’s no other issues besides the gauges. I have not actually been stranded yet or had any weird EFI issues running at the lower voltage. I just haven't had the balls to keep driving around after it drops to 13.0 or 12.9 to find out if it keeps dropping. It is stable at 13.2 at idle in my driveway. It’s not until I get out on the road that I start sweating about the voltage dropping. It’s like watching your engine temperature slowly creeping up but in reverse. You know it’s not going well.

I understand.

I always carry around a spare battery and jumper cables when I am troubleshooting electrical...since I don't want to get stranded.

With all of the "stuff" between your battery post, and your loads...I am ALSO surprised it's losing 1/2 a volt. But I am surprised shocked, and disappointed. You need to go find that lost 1/2 volt. When you find the source of your lost 1/2 volt...you will find the source a varying and high impedance circuit failure. (Since we are both convinced that it is not a ground)

But you never did tell me what instrument you are using to measure the voltage. (And I was pretty detailed in my requirements.) If I find you are using a Simpson 260 Analog VOM...I'm going to trust it. If I find that you are using a Fluke 87 True RMS Multimeter...I do not trust it.

The only thing that is going to cause your AutoMeter gages to hiccup like that is a significant transitory power disruption. (noise) The fact that it coincides with your fan cycling is tricky. There's really only 2 options. The fan is creating noise on the circuit, or the Alternator is reacting to the fan load, and creating noise on the circuit. A third (unlikely) but possible option is that the battery is sulfated, holding a surface charge and enabling what @Broncobowsher described and then the alternator "thinks" the battery is at 14.2 VDC, and then when the fan kicks in...it drains off that surface charge, and then the alternator is not actually capable of charging the full load.

IF the alternator has some shorted (not open) diodes, and is acutally putting out AC, AND the battery is holding a surface charge...then I can see your autometer gages not liking the input source disruption when the alternator starts pushing current. But the Summit gage, (and every other circuit on the Bronco) is too dumb to notice.

Therefore:

1. Remove your alternator. Have the output and diodes tested.
If it fails, do what @ntsqd said, and replace it with a factory (cheap) alternator. The original 1986-89 Mustang 5.0 SEFI ran a 65A alternator. The 90-93 Mustang 5.0 ran an 85A alternator. When the SN95 introduced an electric fan on to the otherwise identical Mustang, it got a 135A alternator.
I run a 30A alternator on my 1989 5.0 SEFI. Which is all you need if you run the mechanical fan. (which you should.)

 

[DanWheeler]

That’s not a trigger wire. And it can’t trigger from that location anyway, because the large cable always has battery power on it already.
The yellow wire doesn’t trigger anything.
Whether you have a one wire, or three wire, it’s still a sensing wire.
And it looks really wonky all bent around at 180° like that. unless that’s just the angle of the camera?

Man, just when you think you know your own rig...

I honestly have no idea what alternator this is, whether it was converted, etc. I really thought it was just a stock Explorer 5.0 alternator that I had jumpered the trigger wire to the positive so it's just always charging, and it was as simple as that. But I guess it doesn't work like that.

It's been working like this since 2008 when I did my EFI conversion... Whatever I did back then I don't remember.

So, I just went out and took a closer look and now I see that the yellow wire is connected to the top post and there's a green wire that disappears back into my EFI harness. (Was an RJM harness from back in the day)

so, guess... I'm full of sh*t on the one-wire thing I'm assuming that green wire goes back to the computer. I sure as heck don't know where else it goes.

To answer your question, this is an Explorer 5.0 setup. If I know myself well, I probably planned and designed it so I could walk into a NAPA and buy an alternator off the shelf.

 

[DanWheeler]

ah, ok yeah this old pic of the RJM harness shows the alternator connection exactly where I'm seeing it on my harness wrapped near the injector and ECT sensor.

Sorry guys - I think I've forgotten more about my own rig than I know anymore. EFI conversion was almost 20 years ago.

 

[ntsqd]

Extend that yellow wire over to the battery. If the jumper is short (let's say under 8" long), then can go to the battery side of the starter relay. If it isn't then go straight to the battery +.

 

[DirtDonk]

so, guess... I'm full of sh*t on the one-wire thing I'm assuming that green wire goes back to the computer. I sure as heck don't know where else it goes.

Hah! You’re not alone
Probably half the automotive world still thinks that any internally regulated alternator is a “one wire” alternator.
It’s been that way since the 70s, and not likely to end anytime soon even with correct information coming over the Internet. That’s why I started asking this line of questions in the beginning. Just to make sure we all knew what you were working with.
If we simplify, there are basically three different types that we need to know about.
1. The old externally regulated models.
2. The relatively newer internally regulated models.
3. And the type with an internally mounted, self exciting (the actual “1-wire” alternator) models.
The fact that most of the first iterations of internally regulated alternators that people came across originally were the almost ubiquitous GM one-wire alternators, it was quite natural for most people to think that any alternator that wasn’t accompanied by an external regulator was therefore a “one wire“ that only required the battery charge cable.
Even some of those weren’t actual one wires, because they still had an indicator light on the dash that was connected to the alternator. They just didn’t always require the light to work.

Yours appears to be a standard 130a Explorer 4G alternator. As you originally planned, something you can get at any parts store probably right off the shelf.

The green with red stripe wire is not connected to the computer. Strictly powered by the ignition switch in the ON position only (not ACC though) through the RJM harness.

 

[DanWheeler]

The green with red stripe wire is not connected to the computer. Strictly powered by the ignition switch in the ON position only (not ACC though) through the RJM harness.

Just confirmed that... +12v on the green/red when the ignition comes on. I know my new ignition switch only has one wire going to the RJM harness so there must be a junction in there somewhere that splits that ignition on +12v over to the alternator.

 

[DirtDonk]

Correct. It’s on the engine side harness buried in there somewhere.
I’ve never taken one apart, but I’ve installed plenty of them. It takes one power lead from the ignition switch that has already passed through the firewall on the original bronco harness, and connects it to the alternator, computer and another thing or two, via the engine EFI harness.

 

[DanWheeler]

Correct. It’s on the engine side harness buried in there somewhere.
I’ve never taken one apart, but I’ve installed plenty of them. It takes one power lead from the ignition switch that has already passed through the firewall on the original bronco harness, and connects it to the alternator, computer and another thing or two, via the engine EFI harness.

That's what I was out there digging around for because I have no recollection of hooking up this red/green alternator wire in all that re-wiring I did. It must be a junction within the RJM harness near the ECU because there's definitely nothing going through my firewall anymore.

There's very little crossover between my RJM harness and all my other wiring. Just power to the RJM harness (which has its own fuses block and relays) and the TPS signal which goes to my old Baumannator.

 

[DirtDonk]

Gotcha. I don’t think I ever installed one on a 1970 or older bronco, that I hadn’t put an all brand new harness in as well.
So other than the Efi, yours is still original wiring?

Hmm, seems like there were still three wires coming in behind the engine for the coil, water, temperature, and oil pressure. But maybe those came through the two plugs you’re showing as well. Hard to remember.

 

[jamesroney]

Gotcha. I don’t think I ever installed one on a 1970 or older bronco, that I hadn’t put an all brand new harness in as well.
So other than the Efi, yours is still original wiring?

Hmm, seems like there were still three wires coming in behind the engine for the coil, water, temperature, and oil pressure. But maybe those came through the two plugs you’re showing as well. Hard to remember.

Wow. Your memory is excellent, and correct. The 3 wire connector for the engine harness does indeed come out of the bulkhead connectors. Here’s my original Ford harness in my 1969. Don’t be fooled by the location, I moved the square holes in the firewall to make room for the EFI upper plenum.

 

[MD]

The way I have the fan wired is working great, so I don't want to mess with that but thank you for the suggestion, I'll still check it out. I'm using a simple high-amp relay for the fan high speed and a standard relay for the low speed which is triggered by the ground switched relay on the Derale controller (yes, the one you linked the PDF for) Not sure about the colors but basically the large black wire is normally the output for that Derale fan controller and I just run that into pin 85 or 86 on the relay switching +12v for the low speed on the fan.

I'm using this 3 position residential A/C switch to allow me to set the Taurus fan to OFF / AUTO / ON / HIGH. Works great.
https://www.amazon.com/dp/B0899XCWKW/?tag=classicbroncos-20

View attachment 949345

The Derale controller is designed for Black to be directly connected to ground and the Red wire is the 'switched' wire, even though it is providing a ground (not 12V) for whatever is being switched.

The reason for this is likely because it is using an N-channel MOSFET, which works like a switch when the Black wire is 0V and the trigger from the thermo sensor is well above 0V, or lets just say it needs to be 4V above the black wire for reference. The most important part is that the load or switched portion must be connected to the red wire.

If you connect the fan ground wire to ground and measure the unconnected positive wire it will probably read close to 0V relative to ground. However if you connect the fan positive to the battery, it will probably settle close to the battery and/or alternator voltage. So if the black wire is connected to the positive for the fan (and the red is connected to battery), the black wire will be closer to battery voltage if the 'switched' controller stays on. That means the ground reference is pretty close to the same voltage as the trigger wire and it will turn off momentarily until the fan positive drops as the fan slows. Then the trigger wire will now be higher voltage than the black wire and it will turn on again momentarily. Then you have a viscous on-off cycle with un-deterministic results. This is an over simplification, but I'm not really good at converting these concepts into simple terms, so I'm cheating. The short version is make sure you follow the instructions to connect the black wire direct to ground and the red wire to the negative side of whatever load you are trying to drive.

 

[DirtDonk]

Here’s my original Ford harness in my 1969. Don’t be fooled by the location, I moved the square holes in the firewall to make room for the EFI upper plenum.

Looks great James. Love that boxwood green.
Or a reasonable facsimile thereof…
What do you do for a fuse box? Retain the original, or add something of your own?

And did you take a FORD harness and modify it, aftermarket, or roll your own. So to speak…

 

[DirtDonk]

The short version is make sure you follow the instructions to connect the black wire direct to ground and the red wire to the negative side of whatever load you are trying to drive.

Thanks for the detail and clarification MD.
I’ve been wondering for years, if all the hoopla around failed controllers and overloading them from heavy duty fans, could be minimized by using the ground trigger to simply trigger a relay.
Taking the direct load of the fan off of the controller and putting it on the relay instead.
Is that a workable solution for the underrated Derale part?

 

[ntsqd]

Were I going to use an electric fan on a project I'd use one of the Delta controllers. Besides being the first in the field and quite probably the leader too, they seem to have a quality product.
http://www.dccontrol.com/selector.htm

 

[DanWheeler]

Quick update… I replaced the alternator with a new, stock 130 amp Bosch unit and the flickering gauges got better… but not fixed completely. The Autometer gas gauge flickers every once in a while when the low speed Taurus fan comes on and the Autometer water temp gauge seems to have stopped flickering all together. Voltage at my Summit gauge started at 13.6 and dropped to 12.9 after 15 minutes of driving. Seems to hang lower while driving and charge back up at idle. Maybe this normal, I don’t know.

My next thing to try will be a big fat ground cable directly from the battery to my gauges.

What a dumb problem… I wouldn’t even be thinking about any of this if those autometer gauges weren’t such snowflakes