O GRM think tank, I need some knowledge...
To catch your brains up to this point: Subject: '92 Dodge Cummins 3/4 ton Diesel Pickup. NipponDenso Alternator. From the factory, the computer acts as the Voltage regulator. This is a known weak point in these charging systems, and requires a computer replacement$$$, or the installation of an old school regulator (my chosen path). the external VR will throw a check engine light, but that's not the concern here. I merely want this thing to give me the 14.7 volts +/- that it is supposed to.
To start, I wired in the external VR as directed- one lead to one field, one to the other field, and power. Popped the VR(I assume). Learned alternators put out 3-phase, and are converted to Volts, and regulated to 14.7V or thereabouts. Neat. Had alt tested=Good once two leads were reversed (I read it didn't matter which wire went to which field, so trying in both positions became part of my testing from this point on).Back together-popped another VR. When I say I popped another VR in this dialogue, I am ASSuming so, as the Alt returned to charging 17 volts (approx) each time. I then wired a relay in the power to the VR to assure it was reading the true voltage from the battery, tried another VR, which I popped immediately (read above). Today, I put a new TRANSPO adjustable VR on, which read properly for moments, then back up to 17 volts charging. Now, no amount of readjusting changes the 17V reading.
There are things I neglected to mention along the way. To wit: The chassis was "Hot" at one point, so I cut the alt lead (which was grounding against the body-presumably because it melted the insulation somewhere along the way), so I ran a new one, Same gauge as stock. at the same time, I made sure the block to alt body ground was good, and ran an additional ground from the alt. body to the VR body (same 2 gauge(I believe) wire as hot).
As I am writing, I feel this melted hot wire requires a second look, but welcome any knowledge anyone can share. Thanks in advance.
Did you wire up the regulator like this: Mopar Electronic Regulator Diagram
That's the diagram I drew for my buddy's book back in '98. The "existing wire" in the diagram is a key on 12v source. It needs to go to both the one field terminal and the regulator at the upper contact in the triangle connector as shown. The diagram was done for an older Mopar alternator, but the concept is the same for the Denso.
I've had very good luck with the Standard VR125 regulator. That's the more expensive one, not the T series. I've had bad luck with several other brands.
In reply to Rob_Mopar:
Yep, sure did. Thanks for the reply. Anyone else...
...Bueller?
Any chance you bought a heavy duty VR with the third pin? If so, that's the reference voltage sensing pin, and the input to the regulator for what voltage actually is somewhere out in the system. If you don't have it hooked up and the VR is expecting it than the VR will keep trying to raise voltage.
I have such bad luck with those regulators lately that I buy them two at a time and screw both to the firewall. That way when the first fails I can swap to the other on the side of the road more easily. Lately I have just been tossing in GM alts instead if there is any indication the Dodge one might have an issue.
In reply to oldopelguy:Nope, 2 pins only. Some of these were Advance Auto cheapies. The TRANSPO was about $60 to the door. Upon inspection, the magic words "Made in China" do appear on the case. Thanks for your input.
Between the two of you, I'm thinking go to NAPA, or the dealer, and get a VR-125.
Is there a chance, the non-powered field wire goes to a ground as well as the second terminal on the VR? I'm learning, but, after fixing hundreds of charging systems getting whooped here.
No, the vr grounds the one field lead through its case and the other gets 12v ignition hot. If you ground the lead than it's just like no vr at all, max output.
That said, any chance you have the two wires on the regulator swapped? To the regulator the input voltage would be coming through the field windings and would therefore seem low, which would cause it to ground what it thinks is the field winding to try and raise output. Since it would be grounding a straight 12v source that may burn up the regulator? They certainly wouldn't be working worth a squat.
oldopelguy wrote:
No, the vr grounds the one field lead through its case and the other gets 12v ignition hot. If you ground the lead than it's just like no vr at all, max output.
Along with that, if the case isn't grounded properly all sorts of issues can happen. Make sure the VR case has a good ground on it, and the alternator housing is grounded too. Bolted to the engine should do it, but the factory harness to the alternator has ground lines as well. Check to see if they are damaged or missing.
Can you give model number of the alternator?
OK, as I thought-do not ground the non-powered field wire. Check. Good info the VR grounds through the case Opel. And yes, I ran a huge grounding wire from alt to VR, and block to alt. The VR is wired like in Robmopar's link. I have several cross referenced sources that agree the power and field wire should go to the top post in "the pyramid" on the VR.
K. McCormic, I'll get right back to you on that. I know it is a big boy.
End shameless bump for selfish and nefarious reasons.
Bumping, and keeping this alive, as my thought process is all but dead. K McC, still can't find Model #, will post next time I pull it off.
I went to NAPA in search of a VR that did not say Built in China on it, Failed, and bought another that does say Built in China on it, but I haven't installed it- Adapted an earlier grill from the PAP, and drank some beer while pondering this problem instead.
I ask because often times you will find (though more often on older stuff) that one alternator frame came in both regulated and unregulated, and you can just find a alternator that bolts in with equal or better output and internally regulated hookup (1, 2, or 3 wires).
44Dwarf
UltraDork
10/9/14 11:47 a.m.
I had VR problems with a mopar 110amp unit few years back. I gave up on well's and Standard brand vr's and took a walk in the junk yard and got a OEM unit off a wreck in the way back of the yard. No problems yet but I've not used the unit in a while.
In reply to 44Dwarf:
Good idea, when it comes to lowest bidder semiconductor containing auto parts, I'll almost always take a unknown used OEM one over a cheapo parts store unit. Looks like basically every chryco vehicle from 70-90 or so used one.
Kenny_McCormic wrote:
Can you give model number of the alternator?
NipponDenso 5234 374
TN2100-4080 12V
FAMILY 120HS
is what's on the sticker.
This sucker's going to a real armature shop.However, its not over til this thing charges properly. I've got a GM alternator that could get the old 1-wire treatment.Any and all help, and advice is greatly appreciated.
Kenny_McCormic wrote:
In reply to 44Dwarf:
Good idea, when it comes to lowest bidder semiconductor containing auto parts, I'll almost always take a unknown used OEM one over a cheapo parts store unit. Looks like basically every chryco vehicle from 70-90 or so used one.
Been There, Done That. Keep ideas coming.
I'm wondering if maybe something is up with your key on 12 volt source you're using. Have you tried making a temporary circuit direct to the battery?
K McC-Yep, Put a relay in the circuit, so the VR sees full battery Voltage. Fired it up yesterday 17 Volts, started squealing. Today I'm dropping the Alt off at an Armature shop-even though it tests good on Advance's Tester. Could a toasted Battery cause any of this? It reads 12.5-13 V before the truck is running.
For Anyone interested, the Armature shop suggested they put a VR on the alternetor body. I said Go for it....
To Be Continued....
I used to have a '93 Cummins Dodge and did this exact work around. I knew at the time the computer was the VR but devised the whole thing up on my own. Basically, I used a VR from a '68 Chrysler Imperial- which is an external, electronic VR- and used the alternator output as you described. IIRC I wired the VR to a toggle in the dash that I had to remember to flick on and off...eventually I replaced this with a wire from the ignition.
Electonics in these trucks were garbage. Speedo flaked out, and the A/C didn't work, either. I lived without a speedo and replaced the A/C controller with a $30 thermostat from Home Depot and some relays to drive the compressor.
Success! I hate to celebrate prematurely, but after no fewer than 6 Voltage Regulators both new and used, Cheap, and expensive, I have a steady 14.whatever Volt output. The Armature shop put an internal Vr on (in) there, and she works. This is also the day I finally got my eye straightened out (fitting an earlier grill, I got either part of a cutting wheel or some steel in my eye-BEHIND SAFETY GLASSES!) In my infinite wisdom, I went to a minute clinic who talked a pretty good show, but despite Dye and Black Lights, missed the crap in there. Today, I went to a real live Op-Tha-Mologist, who had me fixed up inside 5 minutes.
Moral of the story: Sometimes its best to bite the bullet and let the pros handle it.
Signed Dumb, but Happy
