As the title says, I have a plague of failed 90A Denso alternators

I have 3 x '96, and 6 or 7 alternators, with only one working one which is in my DD, but the other 2 still need working alternators

So the issue seems to be failed diode rectifier packs

No diode rectifiers packs are available in Australia

We have RHD alts, but that should not matter for the rectifier

I cannot locate any for sale online on eBay, or searching Google ?

So I have submitted to a cheap Chinese RHD alt, hopefully it at least works, should be here in a few days

My auto elec, who confirmed my probable diagnosis cant get parts, but he said the Chinese Alts are rubbish, with, wait for it, junk diodes!

I see no way around this issue other than I did see for sale from USA an expensive (US$250) external unit that has bigger diodes, gives instructions

here is the link, there is a description of how to fit it to a Denso alt (but no circuit diagram I could see)

Part # QF210 - Quicktifier 210 Amp External Bridge Rectifier - Dual Rectifier Kit w/6 Diodes for Automotive Alternators (alternatorparts.com)

I know what a rectifier is and how it works, 6 diodes basically turn the alt 3 phase A/C into DC

That is what is in the external regulator box does

SO, if I cannot get reliable alternators or rectifiers, here is what I am thinking

Maybe I can build an external rectifier AND external regulator at the same time

I sure have got quick and R&R& stripdown of these units

Any thoughts welcome, where is that Dave dude ?. .he was an ace on electricals

my spare Chinese alt will turn up in a couple of days, I can R&R one in just on 10min now lol (not including getting tools out...or in)

 

Mean Green alternator

 

They must be good, but somewhat over my budget at over AU$1000 delivered ($650US), but now a new problem anyway

I can buy locally (possibly better than my cheap Chinese one) and pay anything up to $550 for others but they would probably be made in China to

Turns out this one is still punishing me

I have the 3 x 96.

MY DD has a working alternator (more on that in a sec)

One is a farm truck, and needs a working alternator

The "spare" is in my backyard, and this is where I have now fitted my $US 90 Chinese alternator, charges 14V on gauge, but the gen light comes back on within a few mins

I have 6 alternators, all confirmed failed, not brushes

Connect my OBD2 scanner, no codes

view live data "voltage ouput", shows an unsteady line between 14-15V, with a few little red crosses when touching 15V.

So I am assuming a problem with voltage regulation now. It would seem the high spikes are triggering the PCM to set the Gen light...why no OBD2 codes **** nose

I guess its slightly possible one of the wires to the ECU that control regulation is defective, but unfortunately it seems more likely to me that failed diodes in the rectifier have also taken out components in the PCM that control regulation

I will do some further investigation, as I need to get it resolved. I will check the PCM to gen wire/s for continuity, but as the gen light comes on, that suggests communication is happening there

I do know external regulator kits are available, I believe the gen light is still set, but that wont matter so long as it is not my daily driver

Applying the OBD live data on my DD showed a perfectly smooth line...at 13.1V...this is lower than I expect, and want, I am fearful my last remaining OEM alt will die

 

I remember I got a Hella (or was it Bosch?) alternator on-line for a good price so, out of curiosity, I've had a look on eBay & there's any number from £99 (presumably Chinese) to £660 (presumably platinum) but most in between & under £300. Now shipping would be the killer for you - but maybe note for a £35 rectifier? Now most say they're for something else (usually French) but "fit XJ" - hopefully you'd know enough to identify the right one from the picture or, at least, ask the seller the right questions. Most of them seem to come from Lithuania, possibly because it's one of those places where they still repair things, but who knows where they are made

Anyway, it might be worth you having a look..

 

Just found this. $256.24 American plus shipping.
91-98 NEW JEEP CHEROKEE ALTERNATOR 165 AMPS, 4.0L LOAD BOSS ALTERNATOR 165 AMP | eBay

 

That can't be right, they changed in '96/97. Although the differences can be got round.

That seemed a lot of money -'til I noticed the "165 amp"

 

Alternators are interchangeable from 91 to about 98.

 

"about 98" must be 97 because my 96 is different from my 98. Then again, I have sometimes wondered if we didn't some of these changes that were phased in earlier on export models.

 

I did have to drill the "holdown clamp" bolt hole on my harness to accommodate the Chinese Alt

Luckily that is the only one of the 4 that is not an electrical collection

As I said, its a pita spending time & money or cars that are not my DD, but you do need an alternator on a vehicle that is driven any distance

In addition, one has about 1hr of driving if yr alternator croaks, then you are stranded, so its an essential spare

I talked to my auto electrician. Technically it is possible to grind away the rectifier epoxy, and replace the 6 diodes, maybe I will have a look at one of the failed ones, its all scorched

The issue of regulation is separate, and also a big problem for XJ owners, as the regulation is in the PCM, so you need to either replace or repair PCM, or run external regulation, which while it does work, I understand will not extinguish the gen light

There is a USA company that supplies an external regulation kit for Jeep Denso, but its US$210 + shipping

I will continue my investigations

While I am a qualified electronics technician, at that time, alternators were not featured heavily in our course, that was for auto electricians, or electrical engineers

 

I trawled back through my eBay purchases & found my £70 Bosch alternator. I checked but he doesn't have any more. However search for similar produced this:-
https://www.ebay.co.uk/itm/131186497...3ABFBM-pys7o1j
The picture looks the same, although different seller. Price is higher (since April '21) but still under £100 - so even with postage it might be worth a look.
Also noticed a used one in Spain for £40 - although postage was nearly £50, so probably about the same to you.

 

Its easy to buy a replacement alternator here, which is what I did

It does not fix a regulator issue though

 

I have had 2 Denso rectifiers die on me after a year or 2 of being replaced and am now on some new alternator which I don't remember the name. It doesn't help you out but they're as crap in the UK as they are in Aus.

 

Hence my quest to find "better" solutions...but it appears I have hit almost a dead end

I suspect our brothers in USA will not be immune from this issue, as I am guessing most of their replacement Alternators are made in China, (or maybe Mexico) lol

Probably not Japan, or the USA

I can get by with 3 working alternators, hopefully the one I got regulates in my other vehicles, and I will then order another, that is the cheapest way out for me

When my spare dies, order another.

 

Next weekend I'll have a look to see where my Bosch alternator was made but, of course, it won't be the US or Japan.

 

An update with good news

Next step was to check all wiring and connections for integrity ( I should have done this first of course)

Green Fusible link wire Ohms out ok

next is to see if the regulation wire to the PCM, and it turns out that the rear plug on the PCM, which has this wire, is not fully clipped home

Once that is done, I apply my "OBD Voltage" gauge and its a perfect smooth regulated 12.8V, same as my DD

Gauge shows 14V, Battery terminals measure 13.8V

I think we can say this fault is fixed

None of the other 6 original alts I fitted showed any voltage at the gauge, I had 3 tested by a pro auto electrician, he verified they are toasted, and I gave him a $50 note in exchange

I will take this alt out of the spare in my backyard, and fit it to my farm truck, you need a working alt to drive that around the back country