Monday, October 27, 2014 - 03:06 pm, by: Chris Shumack(Sharingan)
Hi All, Just wanted to share my alternator repair experience. Been getting the intermittent "Jouden keitou" charging error which is a real pain, especially having the suspension cut-out before hitting a speedbump at UZZ32 speeds. After re-capping the ECU with no success, i pulled out the CRO and determined either a winding or diode was faulty (pic1).
With the multimeter i was reading around 14v - the regulator maintaining (roughly) set point, but as you can see two phases were at 16v and it was dropping to 11v on one of the phases. I traced through a number of cross-reference catalogs and denso, toyota (and honda) catalogs to find these parts, which i was able to source in Melbourne from Trump Auto in Thomastown. All parts were listed as equivalents in the catalogs except for the regulator, which the original UZZ32 specifies 'no choke output'. Seeing as though 'choke output' supposedly is an outdated term for when alternators operated chokes, (for me) having a regulator with enough drive for a choke was an acceptable replacement for one that doesn't. Otherwise, the brushes were a direct match, and the rectifier was from a toyota MR2, which has the rear exit B+ post (actually seemed a little oversized and had to slightly bend one eyelet on the brushes and one eyelet on the regulator). I'd read on a soarer forum (maybe SW) that someone had used the MR2 rectifier with no problems. However, i installed these parts and observed at the CRO (pic2) giving 14.4V with the multimeter but having error of around 8v. I switched out the new 'choke drive' regulator with the old 'no output' regulator, the difference was zilch on the CRO, and 14.0v on the multimeter - so the new choke-drive unit was my reg of choice. Now about the noise... At this point, i'd realised i'd replaced a 6-diode rectifier with an 8 - i assume these alternators have windings wired in the Y configuration, whereby apparently the extra two diodes are supposed to assist high-current at low rpm by balancing current and simulating the 'delta' winding arrangement. Although i've studied electronics, i wasn't able to conceptualise how that works - if it does at all - but as you can see from pic(2) there is much more noise than there was originally.
So i snipped the leads on the extra two diodes (connected to the Y-common, or star-centre lead), and arrived at pic(3) with perfect balanced output on all phases. Pic(4) shows noise at 5mV/div giving total voltage error at 90mV which would also include voltage sag from EFI/ignition, so i'm pretty happy with the outcome.
I have been driving for a few days so far, and have had no charging errors... a few more days and i will be more confident with the repair. If anyone is looking for these parts, here are the results of my part x-ref mission - i hope this list can save some time if anyone is trying to cross reference parts. Just keep in mind that 8-diode rectifiers are listed as replacements for our 6-diode - i'm not sure if this is because some of these parts are cheap copies, or if our specification has just been overlooked. I will report back if i have any troubles with the 'Camry' IN220 regulator and the 'Honda' INR736 rectifier from Trump.
Sunday, February 08, 2015 - 10:49 pm, by: Mario Lentini(Lexus94)
Great work Chris , Wish I had this info last year when I was having major Alt problems .
When I had the Alt problems I found 4 of my Alt all had bad diodes in them , 2 of them shot flams out the back of the Alt when you gave it a bit of Rev's so not good . The Auto Electrician I use (only one in town) couldn't fine a replacement Rectifier with the B+ coming out the back so he used a 2UZFE Rectifier out of the Toyota Land Cruiser , this gave me one problem , the B+ sits on top like the UZZ30/31 so I didn't have much of a choice and put it on but had to change the brace that runs off the back of the Alt to the Head , I feel you could get away with running the Alt without the brace because I am sure that 40mm plate the Alt is bolted to isn't going to flex . I had done over 1000Ks in the 32 and no problems so far .
Peter Scott TryHard South Australia UZZ32 Active V8
Tuesday, March 12, 2019 - 05:12 pm, by: Abs Malik(Tinman)
Thanks for the info. I had a similar problem to this.
My alternator was burning out the regulators in minutes.
Modifying the rectifier from 8 to 6 diodes helped. 2 of the diodes had their legs snipped and bent back. If you take the back of the alternator off with the rectifier at the top, it's the 3rd diode on the top row and the 3rd diode on the bottom row.
The regulator works for a few weeks and then burns out again so there's still a problem.