Is my alternator playing up?

[Selectamatic]

A few weeks ago i noticed that my Alternator light did not come on on my DB 1494, either when running or not. A job for a rainy day...

Anyway, today it came to a head when i went to the tractor and the battery was flat... To be honest, it has been becoming a lasier starter as time goes on, usually perfectly fine.

So, Im starting to think that my Alternator is goosed? Is there a easy way to prove this without shelling out for a new one, or sending it for repair, only to find the problem is still there?

I hate electrics!!

 

[steveR]

Go on eBay and buy a Multimeter for around a tenner delivered.

Go on Google and suss out how to test an alternator. It is a doddle.

You can actually buy wee gadgets for alternator testing, but the meter is so useful for loads of other electrickery, and you WILL find yourself using it quite a bit, even if you hate electrics!!

 

[Thick Farmer]

Get the Swan Vestas out. Best thing to do with a 1494 regardless of the state of the alternator.

 

[john432]

Take the back cover off and remove the regulator brush unit, brushes probably worn down,and not making contact, have look at the slip rings they touch, a clean and a new part often less than £10. Have a Google or you tube ,all will be explained.

 

[Sharpy]

Check the bulb first. On most older machines the power to activate the alternator runs through the bulb, if the bulb is blown then no power to the alternator then no charge.

 

[TripleSix]

As above, brushes worn or stuck.

 

[Mur Huwcun]

You say you have no charging light? It MUST be on with engine off but ignition switched on. The light gets a live feed from ignition switch and an earth through the alternator. Now with ignition on, remove small wire off alternator and earth it to chassis. Light should come on. If it does, you have an alternator issue. If it doesn’t then check the bulb, if bulb tests ok then check for 12+ at the bulb with ignition on, if you gave 12v then check the continuity of the cable from alternator to dash. DB as everything else will have plugs connecting dab harness to rest of tractor, pins and plugs corode and fail.

 

[Pistonbroke]

Had identical symptoms on a 5130,no light coming on at all and not charging and rev counter stopped. Autoelectic shop tested it and said it was " open circuit "which was why no light showing. They didn't have the bits in stock so I had a new alternator. Strangely,the hour clock didn't restart for about three weeks but ok now

 

[mtx.jag]

It’s the bulb,if there is not light on the dash then there is no complete circuit to charge the battery,unfortunately been there and done that after buying a new alternator and still having battery issues ?‍

 

[startinghandle]

The power through light activates alternator then power stops
Check brushes
Check fan belt

 

[Exfarmer]

Bulb blown, replace first, as others say without bulb no charge.

 

[Stock]

If it is a Lucas type alternator then unplug the small wire from the back of the unit and earth it. If the light illuminates on the dash hen the unit is duff, if the light remains extinguished then replace the bulb and check again. If the light illuminates plug it into the alternator and see if it remains lit, if yes then you are good to go, just watch for the light pulsating at low revs which would suggest dodgy brushes...................................................

 

[Selectamatic]

You say you have no charging light? It MUST be on with engine off but ignition switched on. The light gets a live feed from ignition switch and an earth through the alternator. Now with ignition on, remove small wire off alternator and earth it to chassis. Light should come on. If it does, you have an alternator issue. If it doesn’t then check the bulb, if bulb tests ok then check for 12+ at the bulb with ignition on, if you gave 12v then check the continuity of the cable from alternator to dash. DB as everything else will have plugs connecting dab harness to rest of tractor, pins and plugs corode and fail.

Did a bit of mucking about with this today...

Light does not come on, changed bulb for known good one, still no light.

Battery is not charging, 11ish volts at the battery with tractor running or not.

I took the dash out, I get battery voltage with ignition on in the plug that connects to the dash, with dash removed i get continuity through the bulb. But still no light when i connect them both together...

The alternator wiring is combined in one, two thick wires, one thin, Im pretty sure the light does not come on if i earth the thin one...

Any suggestions?

 

[sc4545]

Earth the small wire the light should come on. Most likely your alternator is gone

 

[Mur Huwcun]

If the light does not come on when you earth the small wire you have a wiring issue. Do you have a light test probe? If so you coukd rig it up as a temp battery light to see if alternator charges

 

[Selectamatic]

If the light does not come on when you earth the small wire you have a wiring issue. Do you have a light test probe? If so you coukd rig it up as a temp battery light to see if alternator charges

Thank you, but i am a novice here... i do have a light test probe... where should i put each end?

 

[Mur Huwcun]

One end to battery positive and other end to the terminal the small wire connects to, engine off it should light up, start up and bit of revs and shoukd go off. Make sure to tape up the connections, better still have a helper to start up so you can observe the connections.

 

[Selectamatic]

One end to battery positive and other end to the terminal the small wire connects to, engine off it should light up, start up and bit of revs and shoukd go off. Make sure to tape up the connections, better still have a helper to start up so you can observe the connections.

Ill try that tomorrow, thank you.

If it lights / Does not light, what does this prove?

 

[Mur Huwcun]

If it lights up with engine off and goes off your akternator is ok but you have a wiring problem.

start at beginning again and earth the small wire, if you don’t have a charging light with it earth and ignition on, engine off you have a bulb/wiring issue. There’s a multiplug sonewhere front of cab, that’s first place to go

 

[Selectamatic]

Swapped Alternator for a known good one...

Problem went away.

Put suspect alternator on known good tractor, problem followed alternator.

Winner!

Now then, do I buy a new one or do i repair what I've got?