CHG Indicator MIA - JD 850

[TimberHole]

I'm confused, maybe need to re-read the entire thread. The charge and oil pressure light should come on and stay on when the key is turned on. Does your light come on with the key (tractor not running)? The light should only go off when the engine is running. I assume it is triggered by the higher bus voltage but not 100% sure.

The temp light does not come on with the key but is lit when the sensor sees an over temp condition. Bottom line, when the key is turned you should see two lights, charge and oil pressure. If that's not happening it's probably just a fault in the idiot light circuit. Turn on the key and see if you have voltage at the idiot light.

 

[Smedium C]

K7LN, I tried grounding that wire and didn't see any difference. If the VR they are sending as a replacement doesn't work I'll probably just return them both and get one from hoye. The eBay seller had good reviews so I went with it but I think hoye is going to be the more reliable source from now on.

Timber, the original problem was that the light wasn't coming on whatsoever. With the key turned to ON it used to light but no longer does. I didn't get a volt reading at the lamp but using a test light it shows there is power getting to it. Just not lighting. And the bulb has been replaced and swapped and replaced again. I'd like to have it working but it's not quite as important as the other two which seem to function okay.

 

[TimberHole]

This is the bulb I use. I tried to use some LED bulbs but they acted funky.


Here is the schematic

 

[Smedium C]

I'm using the same bulbs in mine. That's a fresh diagram, easy on the eyes haha. Honestly everything seems to be pointing back to the voltage regulator. Although power is getting to the CHG lamp so why it's not lighting is mind boggling.

 

[TimberHole]

Since there is only one hot wire that goes to the 3 light indicator assembly I think the bulbs get there ground at the 2 senders and the voltage regulator. I would disconnect the yellow/green wire at the voltage regulator and try grounding it. Am I reading that schematic right? I'll be the first to admit me and electricity just barely get along. I know the way to test the temp light is to ground the wire at the sender.

 

[TimberHole]

Here ya go, straight from the service manual....

 

[Smedium C]

I contacted the seller about the wire coming off of the VR and he said this was a ground wire. So taking what y'all said about me not possibly having a good ground while testing the light I went back at it using multiple spots. That's my fault, rookie error.

After finding a good spot, I grounded the VR and that seemed to cure the CHG lamp problem. It now glows although they're a bit dimmer. Once I decide on a final ground location I'll make sure it's nice and clean and maybe that will brighten them up.

Also testing around for a better ground i final got a decent reading on the alternator. It's still not churning power efficiently being at a nearly constant 12.4 (or really just matching what the battery has as every time I start the engine and the voltage drops so does the reading at the alternator). Sorry to waste yalls time on such a simple error.

Is it possible that the bench test of the alternator would produce a reading that wouldn't be consistent with actual tractor output? Because now it seems like the alternator is the issue.

 

[Smedium C]

Nix that last question. Looks like it is the voltage regulator. Even with the tractor running there are no volts getting to the field wire at the alternator. Continuity throughout both lines but just no juice passing through them. Unless there's something I'm overlooking.

Is there a way to circumvent the VR or is it a better option to keep it? Kind of an annoying little device haha.

 

[Smedium C]

I better not mess around with anything like that as I don't know near enough about it.

Sorry, with all the tests I've been doing I must have missed that one amongst them. Just tested at the F & N wires and I'm showing no voltage.

 

[Smedium C]

That'd be the one. I need to step my detective game up to where yours it at haha. Noticed the inconsistencies with the labeling but didn't think it went any further than that. I'll definitely shoot them a message. Seller is very responsive.

Yes, I still have the old mechanical VR. A lot of the wiring has either been chewed through or corroded. Figured I might get to rewiring it one day so kept it.

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