706 amp light not working

ih706 · Nov 26, 2011

The amp(alternator)light on my 706 late model German diesel does not work when the key switch is turned on. If I unhook the connector near the amp light and ground it on the side of the tractor with the key turned on the light lights.

There is a very knowledgeable shop foreman at one of the Case-IH dealerships. I asked him about it. He said how that light works is a long story. I have an I&T shop manual, which in this case, is no help at all. I also have a 706 parts catalog, from which I couldn"t figure much out about the wiring to the amp light.

Can someone shed some light on this for me? Or can someone possibly tell me where I might purchase a genuine IH 706 shop manual? Thanks for any replies.

F706-675sy · Nov 26, 2011

A good reproduction service manual is from jensales.For wiring diagrams go to external_link ( carter & gruenewald co inc ) search your tractor and print them off for free. If you can grd it and light comes on I might suspect a broken wire or a wire that is down to a couple strands which will show continuity on a meter but can"t carry a load such as a light.This wire is on the grd side going to alternator, most likely a light blue wire. I hope this helps.

buzzin duzzin · Nov 26, 2011

special winding in alternator that grounds light when there is no output when alt is producing in that winding light is no longer grounded therefore it wont light

pete 23 · Nov 26, 2011

If the brushes are not making contact the light will not work as they are the ground path for the light. Does it charge, probably not. When I repair an alternator I often leave the pin holding the brushs until I have hooked up my test equipment, and then when I pull the pin out my lamp will go on. This also checks that portion of the internal regulator where field current flows for start up charge. I use a insulated pin of course like plastic or wood.

ih706 · Nov 27, 2011

My original alternator, which I just switched out Friday for a new REBUILT Case-IH alternator was not charging. The original alternator finally gave up after 9700 hours and 45 years, pretty impressive if you ask me. I wanted to put a brush assembly in my original alternator and keep running it, but the shop foreman, after tearing it apart, said it was not worth fixing.

Anyway, to reply to your post, my amp light did not work before or after installing the rebuilt alternator. Yes, I did end up with batteries too low to start the tractor. Luckily I was in the yard close to electricity, so I could hook the battery charger up.

I will do some continuity testing on the wires from the cngco website I was advised of, I may also order the shop manual from jensales, whether I need it for this job or not. A big THANK YOU to all who have replied to my post so far.

Alont · Nov 27, 2011

How these lights usually work is they extinguish
when there is +12 volts applied to both sides/pins of the charge warning light/amp light.
+12 volts on each side of lamp-no current flows and light is out.
The ignition switch, when ON, provides +12 volts to one side of the light, This is grounded/earthed/returned by pin F[External voltage regulator] or pin 1 [Internal voltage regulator]
The light will burn at full brilliance-when the alternator rotates and produces about 14 volts- the light will extinguish
I will post a diagram of your light and connections a.s.a.p.

Alont

Anonymous-0 · Nov 27, 2011

I would also wire a voltmeter across the ignition switch. Will take all of the guess work out of your charging system.

Alont · Nov 27, 2011

Battery +12 volts to ignition switch--charge light
with resistor wired across it[If the lamp fails the
alternator is still energised by the resistor]
----to external regulator ---pin F on alternator.

I am having trouble uploading a diagram.

The charge/telite bulb could be bad, alternator would still charge with the resistor.

My previous post was the "long story" of how the system works

Alont

Alont · Nov 27, 2011

Todd Hamilton wrote:-

I would also wire a voltmeter across the ignition switch. Will take all of the guess work out of your charging system.

Totally agree-there is a load of information a voltmeter can give you.

Also,rereading your post you have already confirmed the lamp actually works when supplied
with the correct electrical inputs.

Alont

706 amp light not working

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