Alternator confusion on a Case-IH 395

[Texasmark]

I recently obtained a 1990 Case-IH 395. Among other things the alternator wasn't delivering. I obtained what was said to be a direct replacement which satisfied the geometry and electrical plug in connector that suited my tractor. Right now I don't remember (senior moment) if I checked it after installation...may have and probably got good readings, but maybe not.

I have the wiring diagram (full set of SV manuals and parts book) and it shows the 3 pin connector with 2 high current windings connecting via the starter solenoid terminal to the battery. The third is a low current sense wire (brown/black stripe) and goes to the instrument panel to say when the alternator is charging.

Well, nothing is happening. Both high current terminals read exactly the same voltage.....as one would expect as they are both tied to the same point...to the battery, and the sense wire starts out at about 0.18V at 600 RPM and moves up to around 0.33 volts at mid RPM. I see no reference to an external regulator in the wiring diagram as the alternator seems to be self contained.

Comments appreciated.

I am going to post this over in the Case site also.....one reason is Case penned the manuals.

 

[Janicholson]

The small wire coming out of part 5 should connect to the regulator, Part 9. There should be about 14.2 to 14.5 volts when running at the battery. One of the two heavy terminals is likely a ground the other should be hot. Trace the wires or look at a wiring guide. Jim
diagram

 

[495man]

I replaced the alternator on a 495, was direct swap plug and play. Didn't have any connection issues.

I also found (at the time) the high output cab version alternator was way cheaper than the regular output open station alternator.

 

[Texasmark]

I spent a little time browsing (learning how to navigate) the parts illustration you referenced [and I found on my parts manual pages 4-28 and 29 (after the fact)] and I see what you are talking about with the pigtail from 5 and the terminal on 9. I didn't see either on the old alternator which carries the same part number 92293C1 (the Lucas A-127-45 Amp)....which includes the pulley and fan, listed in the parts list. A&I products was the supplier and posted that it was a direct replacement. The only electrical connections were the case grounded to the engine block (which I checked and was good) and the 3 spade terminals that mated with the 3 female socket of the tractor's wiring harness. No other electrical connections were on the old alternator nor places for such on the new one.

I understand that the output of the rectifier bridge has to go to the rectifier. In looking through the air vents at the rear of the replacement I saw a 12 AWG (estimate) yellow insulated wire connected to the regulator and was coming from the area of the rectifier assembly. I guess in later models they incorporated that connection internally.

On the two (of 3) terminals of the connector, both tractor wiring harness wires are color coded brown/white. I would think if one was hot and the other cold, the color codes would be different and they both go to the same place; the input terminal (junction box) of the solenoid high current stud where the battery hot is also attached.

Very confusing. I'm open to more of your ideas and thank you for your time.

 

[Texasmark]

My parts list is dated Sept. 1991 and shows it to be for the 395 only. No mention of other higher HP models of the X95 chassis. If
you can remember about when did you last change your alternator and do you recall if it had the plug and a pigtail? I would assume
that the 495 probably being 10 (guess) HP more, if open station would have the same Lucas alternator capacity.

 

[Texasmark]

Here's the rear of an alternator used on my Ford 3910 with a separate regulator:

https://static-assets.imageservice.cloud/3280369/wrg-9367-ford-3600-diesel-tractor-wiring-diagram.jpg

Notice all the outputs are to the regulator except for an unused terminal and the 12v input/output (I guess) lead. Since the IH has the regulator internally, doesn't it make sense that the only output from that alternator would be to the battery and the warning light bulb....with the case providing ground which I checked to battery -.

Since I measured the voltage on the two high current output wires to be the same as the battery voltage (as it should be), and the schematic shows them to be connected to the same point (higher current rating I guess) and I installed a new fan belt and tensioned it properly (after a little run in) the only thing that could be a problem is that the shaft is loose on the alternator and the pulley is turning but the shaft isn't....I'll check that tomorrow....only thing that makes sense....I checked the belt but didn't check to see if the armature was turning.

 

[Texasmark]

I just had a thought. I forget the particulars but I vaguely recall a Delco maybe it was, single wire alternator used on some vintage tractors, especially in replacements for generators since wiring them was a no brainer. I think I recall folks on here mentioning that they had to get to a certain RPM before they would kick in and start charging the battery. In my testing today I had installed a Ford instrument cluster (much cheaper than the OEM and I use them on my Fords and like them) and I was attempting to get the alternator light working. In that process I never had the RPMS over about 900 and this essentially is a single wire alternator...... soooo I will look into that tomorrow also.

 

[Texasmark]

I ran across this this AM: https://alternatorparts.com/what-is-a-self-exciting-alternator.html

I'll try that and in another article it said that you need to ensure that you have a good connection to the engine block for a good return path which I will check. This can't be all this complicated, just finding the loose end.

 

[JimB2]

Hello, my service manual says to check the voltage output at 1800 RPM and it should be between 13 to 15 Volts.
The usual failure on them is the ground brush that rides on the end of the rotor shaft wares out and there is no more ground to the rotor.
My brother has five of these IH/CIH Doncaster built tractors that originally had those Lucas alternators on them and the fix to replace with a one wire Delco 10SI alternator.
Check the front of the engine block where the alternator belt tension mounting bracket is located and there is a second hole in the engine block.
By moving the belt tension bracket to this second hole a Delco 10SI will bolt on and the same fan/alternator belt fit and all you have to do is change the wiring to match a 10SI and there are several diagrams on this sight for Delco 10SI wiring diagrams. The only problem is the Delco 10SI sticks out from under the hood a bit more and is not totally covered weather wise.
PS, the other thing we noticed about the Lucas alternators is, if the battery voltage is too low the alternator regulator will not operate and start charging the battery, so put a battery charger on the battery to bring it up to full charge first before starting the tractor.

 

[rvirgil_KS]

I was attempting to get the alternator light working.

I have a Ford 5610 that had a similar Lucas alternator. On it both larger wires on 3 wire plug had battery voltage. Smaller wire on the plug goes back to charge indicator on instrument panel. That lamp has to be working to excite the alternator to charge. When key turned on charge light comes on, when engine starts and alternator starts to charge the light goes off.

Your non working lamp could likely be the reason for no charge. I would check the continuity from the small wire on alternator plug to and through the lamp and the dash connections for the lamp.

By the way I changed my Lucas to a Delco 10SI 3 wire alternator. (you use a one wire and you likely lose the warning function of the lamp.)

 

[Texasmark]

Thank you sir.

 

[Texasmark]

I thank everybody for their assistance in trying to solve this problem. Seems the problem was that I didn't understand just what alternator design I had and therefore didn't have it hooked up right. Part of the problem was that had I still had the OEM dash panel, just unplugging and plugging the 3 pin connector in to the new one would have been a nobrainer as 495 man said.

Well it was weather beaten and the tractor had a new paint job and I hate a washed out dash on a tractor that looks really nice. The OEM replacement was very expensive...like $1k. So I improvised with one of the Ford types which of which I am familiar, (get them off ebay for a song) but not on an IHC tractor.

Anyway, I got to surfing and found a raw schematic of a 3 terminal, ( I had been thinking this was a 1 terminal like the Delco....even though there were 3 spade lugs on the rear of the alternator) internally regulated alternator and my problem was that the little low current pigtail off terminal 3 goes through the dash light and onto 12v switched.....I thought it was grounded.....had I not kept having a senior moment, I would have realized that the light turns off when the alternator is putting out voltage and there is essentially no voltage drop across the bulb.

The Ford replacement dash panels come with a 6 pin 12v input junction box and I had an open terminal, piece of cake getting 12v switched. I also had some old Ford warning light connectors which had 2 wires as Ford panels are plastic and the mounting clips don't have any electrical contact with the outside world and I needed to get to 12v. Hooked it up, turned the key, got my red lights for no oil pressure nor alternator output (which I didn't have before), turned the key, she started right up, both lights went out, digital MM said 14.07 volts......perfect. Ran the RPMs up to mid range and 14.07 volts. Great little alternator for the A&I replacement at $65 plus shipping.

Problem solved.

 

[495man]

Glad you got it working. It was direct replacement of the original alternator, bought it at CaseIH dealer, just asked for "alternator for 495" Dealer didn't have a ROPS alternator in stock but had a cab one. Given the 495 did not come in a cab version (XL) in US/Canada the alternator must of fit other larger 95 series. Fit perfect on the 495 and no wiring issues, plug and play.

I will assume Lucas but I'd have to check it. Was many years ago I did this. Tractor is a 1991 build too.

 

[Texasmark]

Iterating, had I left the OEM dash assembly in place I wouldn't have had any problem with the installation of the new one which was
exactly the same mounting and electrical lhookup interface as the OEM. The problem was I changed from OEM to Ford dash
assembly and it took awhile to figure out what I missed.

 

[Texasmark]

The excitation provided through the light was what was missing until I connected the other side of the light wiring to 12v switched.

But you made an interesting point in that if the bulb burns out the circuit opens and the alternator quits starting the next time you want to use the tractor. I don't know if it will keep charging once excited, it starts regulating and providing an output and then remove the excitation......

 

[Jim Becker]

I guess the original problem wasn't an alternator problem but was an instrument panel problem.

Typically, once an alternator has started charging it will not need the excitation voltage input to keep charging. In theory, everyone looks at their warning lights when they turn on the ignition to verify good bulbs at start-up.

Proper wiring of the excitation circuit, according to Delco, includes a resistor in parallel with the indicator light. This provides an alternate path for voltage to excite the alternator if the bulb is bad. On a lot of cars this was done by including a light gauge wire in the harness. Do-it-yourself conversions rarely include this resistor.

 

[Texasmark]

Interesting and yes it was my wiring lack of proper reasoning in the mod., not a problem with the alternator.