4th Gen: Alternator not Charging Battery Issue - FIXED!!

[arif_manji]

is there no warning lights on the dash? maybe try a battery booster when starting it up... and check the belt is tight..only issue ive ever had with alternator on a 4th gen ( in 20 years of running them daily) is when the crank pulley came loose but that threw up a warning light on the dash along with the engine cutting out

Hi @vanzep

No warning lights on the dash. I will try the booster and see if there is any change. All terminals and belt tightness checked and tightened to the Honda Prelude's detailed manual. When the engine is running, it is smooth as anything and drives absolutely fine

[arif_manji]

If the alternator works on another car and is otherwise without fault it can only be continuity between either the battery and the alternator or the exciter circuit and the alternator. There isn't much else technically to it, the charging circuit is pretty simple so if the alternator is definitely ok the problem must be the wiring as mentioned already

My thoughts exactly! Having looked through the manual, I need to investigate the ELD in the fuse box. I have notice there are two types of fuse boxes in these 4th Gen. One that has a ELD with a plug and one without? Does anyone know why this is?

[arif_manji]

Wires itself should be fine. But you should check all connectors. What you can try is unplugging battery while engine is running. If it will stop than there is no connection between alternator and battery. Loose connections provide high resistance which will not affect multimeter as bad as when you draw higher current.

Hi @K30DPC

I will give this ago and see what happens, thanks.

[arif_manji]

All,

I have notice there are two types of fuse boxes in these 4th Gen engine bay. One that has a ELD with a plug and one without? Does anyone know why this is? And if corresponds directly with the alternator?

[vanzep]

No idea - all the ones i have seen have a plug

[arif_manji]

No idea - all the ones i have seen have a plug

So I have discovered that the UKDM don't have a ELD plug to the engine fuse box and the JDM have a plug.

[vanzep]

Yes that would match all the ludes i have had were/are jdm.
I may have a spare jdm fuse box with eld so let me know if you need

[arif_manji]

Yes that would match all the ludes i have had were/are jdm.
I may have a spare jdm fuse box with eld so let me know if you need

Thanks @vanzep , I've got about 3 UKDM's and 4 JDM ones.

[arif_manji]

Guys, does anyone know if there is a difference between the UKDM and JDM alternators?

I've noticed that on the UKDM, the alternator plug is:

S FR
IG L

The JDM is:

C FR
IG L

What is the C & S difference?

[RattyMcClelland]

I was about to reply but you may have discovered the issue. You have to make sure the alternator is like for like and not from a JDM car.

This was my issue 6 years ago. The last page may answer your problem. Only a JDM 5th gen alt works on my JDM Type S. I tried all other alternators for prelude and all didn't work.

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