Electrical question
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=132307
Printed Date: 08 May 2025 at 5:01pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Electrical question
Posted By: Acmichael
Subject: Electrical question
Date Posted: 06 Dec 2016 at 5:49pm
| Rewiring my c after restoration and have no power to lights and amp gauge not showing it is charging. I have power to both terminals on the gauge at all times. No power to the light terminal on switch when on or off . All other terminals have power. Why would the switch not be sending to the light terminal? Have a new switch from Steiner any info would help thanks. |
Replies:
Posted By: Acmichael
Date Posted: 06 Dec 2016 at 6:15pm
| I also had the generator checked and its good |
Posted By: Gerald J.
Date Posted: 06 Dec 2016 at 6:29pm
|
If the ammeter isn't indicating it could be rusted fast or isn't wired right. There should be two wires from the ungrounded battery terminal. One to the starter and one smaller one to the ammeter. Often the ammeter wire runs from the starter switch terminal to the ammeter. The other terminal on the ammeter has to be hooked to the B terminal of the voltage regulator or cutout. And that same terminal on the ammeter goes to the ignition switch (presuming not a magneto) and the light switch. Though the light switch could be connected to the L terminal on the voltage regulator when present. With the ammeter wired that way it sees all the battery current but the starter charging or discharging and the generator output can supply the light and ignition loads plus the battery charging. That's modern wiring. The original C light switch supplies power to the lights and grounds the generator field for full or partial charging rate with a three brush generator and a simpler cutout. It leaves the control of battery charging to the operator and is prone to overcharging. It has to be wired right and I've read on this forum that many of the replacement switches except those sold by Steve (NJ) are not compatible with the battery box (which has to be grounded well for the generator field section to work). I have a C shop manual on line with wiring diagram for B, C, CA, and G at: http://www.geraldj.networkiowa.com/Trees/Allis-Chalmers-G-B-C-CA-Service.pdf" rel="nofollow - http://www.geraldj.networkiowa.com/Trees/Allis-Chalmers-G-B-C-CA-Service.pdf Gerald J. |
Posted By: Acmichael
Date Posted: 06 Dec 2016 at 6:46pm
| The amp gauge is new and I wired it according to the wiring diagram in the manuel. Neg terminal to the voltage regulator/cut out and a seperate wire from neg terminal to the light post on switch. pos to the field ground. The switch I got from Steiner doesn't fit the box exactly. So that could possibly be an issue that the switch isn't grounded properly. |
Posted By: steve(ill)
Date Posted: 06 Dec 2016 at 7:14pm
|
the replacement switch has a bigger resistor on it. It will not fit in the B box correctly. You may have a pinched wire or grounded wire that is not suppose to be. Try with the cover loose and wires exposed out of the box. ------------- Like them all, but love the "B"s. |
Posted By: Acmichael
Date Posted: 06 Dec 2016 at 7:22pm
| I tried the open box and still couldn't get power to the light post. I will go back and check all my connections. Which post at the generator should I have power? At the voltage regulator or field ground? |
Posted By: Gerald J.
Date Posted: 06 Dec 2016 at 8:11pm
|
With the engine not running there will be power only at the battery post of the cutout, nothing at the field or armature terminals on the generator or the A terminal of the cutout. The switch gets its ground through the battery box and the mounting of the switch to the box, paint prevents that circuit at the switch mounting and the box mounting. There are two independent poles on the switch. One turns on the lights, the other grounds the field through the resistor or direct depending on the switch position. Gerald J. |
Posted By: Chalmersbob
Date Posted: 06 Dec 2016 at 9:11pm
|
You wrote "pos to field ground" not sure what you meant by that statement. The generator field attaches the 3 position switch at 1 end of the resistor. If you have power out of the amp meter to the light switch, could you have that wire attached to thee wrong terminal. I don't know anything about the replacement 3 position switches. Only the original ones. Bob ------------- 4 B's, 1 C's,3 CA's, 2 G's WD, D14, D15, B-1, B10, B12, 712S, |
Posted By: Acmichael
Date Posted: 06 Dec 2016 at 9:18pm
| There is only two terminals that wiring can be attached to on the autolite generator I have. One place being the voltage regulator/cutout other is a single terminal that I ran to the positive terminal on the ammeter. |
Posted By: steve(ill)
Date Posted: 06 Dec 2016 at 9:20pm
 ------------- Like them all, but love the "B"s. |
Posted By: Chalmersbob
Date Posted: 06 Dec 2016 at 9:21pm
|
The 2 terminals on the genny are marked A & F. A goes to the amp meter and F goes the the 3 position switch. As long as you get can identify the F terminal, the other terminal goes to the switch. Bob ------------- 4 B's, 1 C's,3 CA's, 2 G's WD, D14, D15, B-1, B10, B12, 712S, |
Posted By: Acmichael
Date Posted: 06 Dec 2016 at 9:30pm
| Correction ammeter pos terminal to the starter switch |
Posted By: john(MI)
Date Posted: 07 Dec 2016 at 1:01am
|
The wire is coming to the battery/starter from the + terminal of the ammeter. It should show a charge at that point. If it does not it is bad. The wire coming from genny to the - terminal also goes to the starter switch and the light switch. If the lights don't work, it appears the genny is not putting out 12v, but you have 12v at the - term of the meter so the light switch is not grounded. I think you have two problems! ------------- D14, D17, 5020, 612H, CASE 446 |
Posted By: Gerald J.
Date Posted: 07 Dec 2016 at 9:36am
|
On most generators the A post is a larger diameter stud than the F post. Simply because the field current is only a few amps maximum while the A is 20 to 30 amps maximum. Gerald J. |
Posted By: Acmichael
Date Posted: 07 Dec 2016 at 6:41pm
| got everything working today power to lights ammeter showing charging just waiting on the light reflectors to come in now to finish assembly. When will I learn with these 6 volt systems grounding is crucial and can be any paint touching anything that is a ground. Thanks for the help guys |
Posted By: Gerald J.
Date Posted: 08 Dec 2016 at 9:48am
|
Grounding is crucial for all tractor and vehicular electric systems. Even at 48 volts. But there is less tolerance for a poor connection at 6 volts because the voltage drop from the higher current for a particular power load is a bigger fraction of the supply voltage. Clean the battery posts and connectors twice a year on 6 volt systems, they need it that often even with daily use. About every other year on 12 volt systems. Gerald J. |
Posted By: Steve in NJ
Date Posted: 08 Dec 2016 at 3:57pm
|
Be very CAREFUL with that aftermarket 3 pos. switch. That thing does not fit correctly in most AC instrument boxes and shorts out! I had quite a few of our customer's fill me in on that switch because of that. If you want the real OEM correct switch, we offer the switches outright if you don't have a core.
------------- 39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife |