Hi All

Im new on here and my first post! Currently building a Stylus and coming to the end now!

Got an issue with the alternator that I have. It is a standard Nippon Denso alternator that would have been supplied with the Toyota 4AGE engine originally.

The issue that I am having is that I cant get any voltage out of the L terminal when the alternator is running for it to turn out the dash warning light.

I have 14V in the IG and S terminals when running and 12V when not, so it is charging fine.

the max voltage I get out of the L terminal is 0.27V, so next to nothing!

The supplier of the alternator sais it should have 8-9V coming out of it, which doesn't sound right to me!

I am running a standard filament bulb on the dash. The alternator is earthing fine and turning the light on when not running.

The wiring for the plug is Type 3 in the following link: http://www.locostbuilders.co.uk/viewthread.php?tid=158490

It appears to be a common issue with the warning lights on these alternators, but no real information on the actual work around to get the light to go out.

The alternator has come from California as that's the only place I could get a re-con unit at a decent cost!! So not easy to exchange it for another to try, but it is charging!

Any help would be appreciated as ive come to a dead end now!

Thanks

Matt

not sure if it applies to the nippon alternator, but
usually the warning light goes to ignition live, and earths through the alternator

edit
ps Welcome!

[Edited on 6/6/16 by gremlin1234]

pretty sure you will need a diode between charge light and alternator, think i used the original one which was buried in the original loom.

hth

Rob

I have an ignition supply going to the warning lamp. The L terminal from the alternator is then connected to the other terminal, which when the alternator is not running it goes to earth and creates the circuit, turning the lamp on.

When the alternator is running the L terminal should be putting out 12V which will then give a 0V PD at the lamp, turning it off.

However, I don't get the 12V from the L terminal when running...

Adding a diode will prevent the current from back flowing to the alternator, which if I was using an LED then usually you need one, but for a standard filament bulb I shouldn't as far as I know.

You don't need to connect "L".
"L" stands for Load it is a signal to the tiptop ECU in the form of a square wave the duty cycle of which tells the eve the electrical load on the alternator.
50 percent = zero load. 0 = full load.


Denso Alt Duty Cycle Idle

I have been thinking that it may well be a 5v square wave signal from it and im only seeing 0.27V as im using a standard volt meter and not an oscilloscope.

Any ideas on converting the signal to a voltage?

Have you connected the S tap? I only connected the L to 4 watt lamp, IG to an ignition switched live, no other connection and it works fine.

yes the S term is connected. If I don't have it, then theoretically the alternator will be sticking out full load all the time as it will think the battery is at 0v?

quote:

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Originally posted by ttalps2000
yes the S term is connected. If I don't have it, then theoretically the alternator will be sticking out full load all the time as it will think the battery is at 0v?

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It is how many amps it will be putting out that is worrying. If it puts out full amps at all times, then it will cook the battery.

Will try disconnecting the S terminal tonight and run an ammeter in the circuit and see what it does.

Never get these issues with a Lucas ACR!!

I had a similar issue with the low voltage from the bulb out. Turned out to be a faulty regulator at the back of the alternator. I bought a replacement regulator, fitted and it now works. It was a 10 minute job to replace once the alternator was out of the car.

This is what concerns me. Being a recon unit I would have expected them to have tested all that!

Just found this on ebay: REGULATOR FOR NIPPON DENSO ALTERNATORS REF 4677 131459

If you read in the description about the L terminal, sounds like it has nothing to do with the lamp!!

If this is the case, is there any other way of detecting it is charging to turn the light out, other than connecting the bulb to the oil pressure warning light to get through IVA and when the main lights go dim realise it is not charging!!

I don't think there is any iva requirement for the alt charge light

Tried this evening without the S wire connected, still dead!

The voltage regulator is working as it is regulating to 14.4v constantly, so the diode pack is also ok.

Opened up the alternator and it all looks new inside! The voltage regulator looks new too! However it gives out nothing at all on the L terminal, no matter what i do.

The supplier in the USA has agreed to supply a new voltage regulator to see if that resolves the problem.

After that, the bulb will just be removed on the dash and be done with it!

thanks for all the help so far! Will get to IVA one day soon!!

L terminal is only to supply data to the engine ECU it serves no other purpose.
When the alternator rotor coil is full fielded it is at max output terminal L will show zero duty cycle and hence read zero volts.

S terminal is connected direct to the battery to provide accurate battery voltage information to the alternator regulator without any voltage drop due to the charging current.

IG is the ignition warning light terminal normally on cars with Denso alternators there is a resistor wired in parallel to the bulb to supply sufficient current to kick start charging.

B+ terminal is main cable that connects to battery.

Normal charging voltage with these alternators is 14.4 volts under normal loads.

This scannerdanner YouTube video might help https://m.youtube.com/watch?v=--AdY8z1QfU



[Edited on 7/6/16 by britishtrident]

thank you for the information! I will re-wire it again tomorrow and see what it does.

The bulb has an ignition supply to it and then the earth side going to the alternator. Is this the right way round, or does it need to be reversed? I'm using the premier wiring universal loom, so is all based around standard Lucas components etc.

Is it just the 4age alternator that works in this way?

My alternator was charging fine at 14.5v also, but there was little to no voltage coming out of the ignition light terminal. It was one particular part of the regulator which had gone. The replacement one fixed the problem.

My regulator went due to a loose connection on the B+ terminal which fried the alternator regulator as the charge was not going back to the battery.

Britishtrident - connected up the alternator as suggested and have no light at all now, but still got a charge output.

I get 14v at the IG terminal with the ignition on and when the car is running.

I have a new regulator on its way, so will try that next. Any other suggestions?

Update - I have received a new voltage regulator from the supplier of the alternator. The model number is different, although they look the same.

The IG and L terminals are round the other way too.

If i have all 3 wires connected up, the alternator does not charge and no dash light comes on or goes out.

If i disconnect the S wire then i get 14.8V output, but still no dash warning light working.

I have tried connecting the light to the IG terminal as suggested, the alternator then does not charge.

SO, the IG terminal is def my ignition exciter as that is the only terminal that will kick the alternator in. It also appears to be the only wire that i need to get it to work!

I can live without the dash warning light if i have too.

I am going to put an induction meter over the charging cables tomorrow hopefully and just check what output the alternator is giving in terms of amps.

The voltage dips by around 0.2V when you turn the lights on and then recovers within about 3 seconds, so the regulator is working with load etc.

My only concern is that it is now putting out the full amps rating constantly, hopefully will soon find out!

Matt

put the amp meter/clamp over the cables and when first started the alternator is putting out around 20 amps and very quickly backs off to about 5 amps after a minute or so when it has topped up the battery.

Once load from the lights etc has been put through it I am seeing around 27 amps in total load (heated screen yet to be fitted)

So....it is regulating itself in terms of current and voltage, so I am leaving it at that now!

Thank you for all your help everyone!

Matt

when I did some searching on the Nippon alternators, I found an 'industrial' spec one for fork lifts and such like. it may be the control board you had is for one of these.

hope what you have now continues to work well.