Testing a Mopar Alternator and Voltage Regulator On the Car
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- เผยแพร่เมื่อ 28 ก.ย. 2020
- Is the battery in your car or truck going dead? Is the battery meter reading low? In this video we look at how you can test your classic Mopar charging system with just a voltmeter and a wire.
Multimeter: with alligator clips: amzn.to/3HiP3mu
Mopar Performance Voltage Regulator: amzn.to/3ocDohw - ยานยนต์และพาหนะ
you saved me from taking my alternator from my Eclipse (pain in the but) to take it to test. I removed the OEM ECU for an Aftermarket and of course lost the voltage regulator. Bought the 2VR1 and wired properly but nothing. It does not charge a brand new battery. I am heading to the garage now to test that and make a video for my channel. Will give you props on my video.
Thanks brother!
That's a hell of a fuel line you got on that carb. A long time ago an old timer taught me a trick to check the alternator. When it's running you can touch a screwdriver to the bearing on the back of the alternator and if it's magnetized it's working.
As someone who doesn’t fucking understand electricity, I’d like to extend thanks because this actually helped. Now I just need to figure out if my problem is shitty wiring or the voltage regulator.
Excellent video! So we’ll explained even with all the background noise! Thanks a bunch
Such a simple, to the point instructional video I need to understand my task!! Thank you, for your time!
This is an awesome video! This will indeed help me with my old 71 Dart!! Thanks!
This is a really well made, informative, and accurate video. Thank you so much for your efforts!
Thank you sir very simple, straight to the point and informative.
Great video, easy and clear to understand. Thank you!!
Great video, no BS, to the point. Pretty sure it's the alternator and it's fairly new.
"new" anymore just feels like "first replacement". Finding good parts is hard
Great video thank you
ok jumping output of alternator and are we doing anything for the input coming from battery to alternator or leave it unplugged or jump to positive on battery
So my 85 d150 does just what you show, with key off main altenator wire shows battery voltage and both field wires show no voltage with key on the main wire drops just a little and one field wire shows 11 volts and the other shows about 1.5 volts, truck puts out 14.3 volts when running, runs great
on my hot rod ive got an 87 d150 wiring harness put in a 47 1 ton truck, when key is off main wire shows battery voltage and so do both field wires and when in run position same all three show battery voltage, and when running alternator is only showing battery voltage, so my wiring is probably messed up?
going to try this with my lebaron
Ok so the two field wires that goes to the input of alternator and other end connects to the center of the voltage regulator plug the output from the alternator to side of voltage regulator. Now the input also is powered by battery or connected to fuse box 10 amp. correct?
What if both field wires are testing out at above 10v? Im getting no charge, new alt, new bat, new reg. I was getting an over charge, i think i got a bad wire somewhere but not sure which one to chase.
Done it but wasn’t getting 14v just like 13.6 or something like that but without jumper wire I’m only running 11v
Is there any way to test a voltage regulator on its own ? Or with a multimeter?
Hey Y, I watched this great video last night and went out and tested my 85 Ramcharger today. I have no voltage with key off on field wires. 11.5 on both wires with the key on but engine dead. I see others have experienced this same thing. What likely is wrong? I keep researching, but I'm guessing I may change the brushes in the alternator. Oh, by the way, I checked two other Dodge's sitting in my barn, both checked out according to this video. No volts on field wires with key off, with key on one had battery voltage, the other was very low. Thanks again for the excellent information.
The field circuit basically comes from switched battery voltage (so ~12V) in one side, out the other, then through the voltage regulator to ground. the regulator acts as a variable resistor to control current through the field wires, and therefore the amount of charge. Since the field wire in the armature is long (lots of windings) I'd expect there to be some voltage drop there - I'd have to ohm-out an alternator to know how much drop to expect. If you full-field it (i.e. ground the terminal that goes through the regulator like I did in this video - using a test light is probably safer than a 0-ohm wire) then it should start charging at max capable output.
@@YoshimoshiGarage OK, thanks to a few clues from your reply, I have caught myself up on alternator basics. The brushes contact the two slip rings, which are connected to the rotor windings. If the voltage at the two field terminals is nearly equal when energized, then this indicates a problem with insulation breakdown of the rotor. To check, I removed both terminal wires and read the resistance. I then compared this to the resistance of known good alternators. There was a large difference. I can infer this particular alternator is bad. In summary, if both terminals have nearly identical voltage when preparing for the test you show in the video, there is no need to proceed with the final test of shorting out the field terminal; the rotor is bad.
great presentation,. thanks, it really help me..
great video, easy to follow. Question, with my key off I have 12.6 at alt post and 0.0 at field spades, when key at start alt post 12.3 and BOTH field spades 10.6. Should field spades have different readings ? 440, recon alt, new external reg. Thanks for your time
Yes, there should be voltage through the field windings
You use the term "Output connection" for both main output, and field winding output...confusing!
I did however understand that it is the FIELD WINDING OUTPUT (low reading on test) that is grounded using jumper wire.
I petty the guys that "misunderstands" your confusing instructions and connects the 12V OUTPUT to ground though....
I suggest ADD TEXT to video to avoid mix up??
A good suggestion.
The best way to full field a Mopar alternator is to remove the insulated washers from the brushes. It's a great way to make your stereo louder for a few minutes. It sounds great, until your headlights and taillights all blow out, and the insulation of some of your wiring starts to melt.
When I touch the blue wire to ground as you did. my voltage stays the same and I get sparks between the blue wire and the battery ground. If that indicates a bad alternator, could a bad alternator have ruined my voltage regulator also because it was testing bad also so I replaced it as well?
Sounds like it's making a connection through the field (so sparks) but it's not charging. Probably bad diodes in the alternator.
Great vid but on a Town and Country 2011 where would be the voltage regulator in the ECU or in the alternator?
Sorry, I don't know. I'd guess it's most likely in the alternator itself
I did this with the key off and got 11.7 volts at the alternator field terminals and they were both the same at 11.7 volts? With the key on I got it to spike up to 11.8 volts at both terminals and I would say I have a wiring issue. I installed a new alternator thinking it had gone bad yesterday because I was losing voltage while driving. Didn't perform the jumper wire test yet. I'll try that next. Thank for the video
With the key off you should not have power at the field at all.
What if you have battery voltage on both field wires with the key in accessory
The two field connectors are really just 2 ends of the long field windings in the alternator, so if you have voltage at one, you should have voltage at the other (it will be lower on one due to resistance through the field winding). If you don't, it indicates a broken field wire. I would also expect voltage to be there in accessory, since the alternator isn't spinning at all, so the regulator should be telling the alternator to charge.
What if I don't have power at the field wire when the car is in the on position? Thank you for the video and the help.
Chase the field wire back, then. It's probably damaged
@@YoshimoshiGarage I was assuming the issue is the voltage regulator. I have power on the ignition side of the voltage regulator. I traced the wires back to the voltage regulator and I see no obvious signs of burning/fraying. Thanks for your help.
@@YoshimoshiGarage Meaning I traced the field wire from the alternator to the VR box.
Great vid, Did exactly this up to run test as both field wires were showing 11.40V when in on position. Ideas?
11.5 on the regulator side seems reasonable - that says that the alternator is being energized and should be charging, so the output on the charging post should be somewhere around 15 or so at that point. The voltage is going through the alternator windings, so the ground-side field wire will read voltage. A little surprised it's the same and not at least a little lower.
@@YoshimoshiGarage this was when in not running state and only in key on position. I was expecting very low voltage on the output side
I definitely would expect a larger drop across the alternator field, but I'd have to go check one. It feels like it's low resistance, which could mean an internal short.
Hey ZP, I watched this great video last night and went out and tested my 85 Ramcharger today. I got the exact same results as you. To clarify, no voltage with key off on field wires. 11.5 on both wires with the key on but engine dead. What did you find out was wrong? I keep researching, but I'm guessing I may change the brushes in the alternator. Oh, by the way, I checked two other Dodge's sitting in my barn, both checked out according to this video. No volts on field wires with key off, with key on one had battery voltage, the other was very low.
Everything is OK untill I get to the step where to ground the green terminal. Which I do and when I do it sparks and melts the brush insulating housing. And the alternator does not charge to full capacity. I just melt stuff.
What does this mean? My alternator is bad? or wiring?
It means there's probably a short in the alternator field windings giving nearly zero resistance to current flow to ground.
With the key on, the output was less but both field wires had just .01 reading. What would that indicate? Great video by the way.
One field wire is hooked to ground so it will always read no voltage. The other side goes to the voltage regulator and with have anywhere from 0V to probably 12-ish depending on the overall voltage of the battery. Take a look at my video on bench-testing the regulator for a little more info, but I suspect the regulator is bad. th-cam.com/video/nkoZ3E4-tVk/w-d-xo.html
Great vid. Question: 1970 Dart with brand new Regulator and brand new Powermaster 95 amp 3-wire alternator. Getting the appropriate voltage reads in “off” position, however voltage stays the same at all outputs when ignition is turned on but engine not running. Haven’t tried the engine running scenario yet. Any guesses?
If the field connectors have voltage when the ignition is on, but not off that's expected.
@@YoshimoshiGarage I actually am not getting any voltage in field wires when key is in the on position, they both stay at 0 as opposed to having voltage show.
Sounds like a problem in the wiring from the bulkhead. Trace the field wire back and find where it's broken
So I did this, and when I ran the final run test and ran the field wire to ground my engine sputtered and died. I did the test on a 68 b body. There was no charge as my meter dropped to around 11 volts. I'm guessing that this means my alternator is no good, but I'm a newb when it comes to charging systems.
If the voltage didn't go up when you full-fielded it (powered that field wire) then the alternator isn't producing any voltage and either it's bad or the charging wire (the big red one) from it is bad.
Quick question for you. With engine running and I connect the jumper wire to the output field wire and than battery negative, I hear a load change just like in your video but my multi meter sees no voltage change at all. I have the wire to alternator output field disconnected. Hearing the load change makes me think it’s working but not seeing the meter detect the increase in voltage concerns me. What am I missing? By the way, great video!
If the load is changing, verify the meter settings and connections.
@@YoshimoshiGarage multi meter is functioning properly, correct settings as I had it attached to battery just as you described and it was reading 12.40 +/-. I can hear a engine load when I ground the alternator field wire but no change in voltage. I’m also smelling a slight burning oder. I think I’ve followed it back to the alternator. The question is, could the alternator sense the load but internally not discharge it?
Ok, with the key on I have full battery power one one field lug and zero on the other... bad alternator?
Sounds like field windings or brushes, but yes, likely the alternator
Hi just came across this video.
I have a 71 challenger and it's not charging.
I did the power off test. Everything checks out. 12.5 on the input and 0.0 and 0.01 on the fields.
When I go to do the on key test.
I am getting 12.3V on the input and 0.6 (blue) and 0.0 (green) on the fields.
If I'm following the video correctly It sounds like the wires going from the voltage regulator to alternator are faulty. Is this correct?
Field signal isn't happening. Could be the regulator itself or it could be a wire
@@YoshimoshiGarage just replaced the regulator. Did the test again. Nothing.
I then tried a bypass of the wiring harness. Ran two new wires both from the regulator to the field attachments on the alternator. Still no luck.
Is it easy to burn out a regulator?
I appreciate the help.
The regulator ground through the housing to the firewall. Make sure it's got a good, clean ground there (bolt is clean, area around the bolt hole on the regulator isn't painted, etc) e
@@YoshimoshiGarage so cleaned up the the two holes where the regulator mounts to firewall, cleaned the bolts and removed any paint.
Went through the tests.
Off position checks out.
Key turned on. Saw a drop from 12.5 (off) to 11.8/12 the field terminals. One registered 0.2 the other 0.0.
When we had the car running.
Volts on the battery dropped to 2.19 to 2.3 and stayed. No charging occurred when I ran a jumper from the alternator to battery.
Car starts fine. Volt meter is registering at 11. The stock Amp meter in the dash I think was blown could that be the culprit? It's still connected.
The ammeter has no effect. If you give 12v to the field, the alternator will charge (unless it's bad). If you put a jumper in there and it did nothing, I'd suspect the diodes in the alternator are cooked.
To be clear I have a single wire alt. and ran through the testing procedure and the last test running with the single field grounded made no difference in charging rate, I assume then it is an alternator failure.
So a single wire alternator is different - it grounds the second field connection through the case. Dual-field is an "A circuit" where one wire is hot and the regulator controls the ground on the other. Single-field is a "B Circuit" so the alternator has one field grounded internally and the older-type regulator controls power to the field. To test that system, apply 12V to the single field and it should start charging. If it does, then your problem is likely the regulator. If it does not, it's likely the alternator.
@@YoshimoshiGarage So with the car running ran a jumper from single field prong to the positive battery terminal on the battery and it seemed to drop voltage also jumper wire got very hot.
@@sueleake7436 Sounds like the field winding in the alternator is shorted (assuming you disconnected the regulator when you did this)
It would be great if you could use a light and also aim the camera at the terminals you are referring to so we can see what you are talking about.
I definitely could have done better. Now that it's warming up out, I'll try to do an updated video that better explains it, along with the difference between the older 1-wire and "newer" 2-wire alternators since there's a big difference in how they work.
Hi there. I just did the load test with car running and grounding the field wire. Car died immediately. Your thoughts?
And it was the green field terminal.
Did the engine speed change, like it put load on the engine and that caused it to die, or did it act more like you just shut the car off? The first would be because full-fielding the alternator causes it to drag on the motor (though it shouldn't be enough to kill it unless the idle is super-low). I can't come up with a theory on the second. The charging and ignition circuits are completely separate
@@YoshimoshiGarage it would just die. I had the rpm at the time around 850. I just tried it again this evening and I raised the RPM before touching it to ground and it still wanted to die. Wire had a pretty good spark and wire got hot on the fingers. Never really rev'd up oth e then me holding throttle back. I'm guessing I may have a wiring issue under my dash.
Why would both input and output have 9+volts
Do you mean both field wire connectors?
@@YoshimoshiGarage yes both read 9.3
That tells you that the stator windings in the alternator are good, but if the battery is at 13, then I'd trace the field wire that isn't going to the regulator back to it's source and check the connection. It should be at or near battery voltage
This video is so good I fucking took notes. Thanks!
4:44 I just tried that and al I did was fry the end of the jumper wire.
Man, sorry about that! So what that means is the field connection is running straight to ground. That's definitely an alternator problem. Could be the brush holder is broken, could be an internal field coil short.
@@YoshimoshiGarage see my previous comment....perhaps a misunderstanding of which OUTPUT is grounded?
Is your smoke alarm going off? 😄
They were driving a skid steer next door doing landscaping. It seemed like they only used it whenever I was trying to record. 😄
Dam that's beeping low buck video
My OCD could not let me concentrate with the stupid backup alarm constantly going off every time you would say something throughout the entire video.
Terrible sound i m afraid
The beeping sucks
They were running a skid steer on the lot next door. Not much I could do about it.