AHJ

Hello

Yesterday, my 96 LS400 gave clicking noises when trying to start it. CAA jump started it for me and gave me a diagnostic printout showing an open diode.

I'll have to remove the alternator and take it for testing.I might have to change the rectifier holder unless I can get to the diode.





Diagnostics after jump start

fixmiester

The alternator can be tested without removing, just like he did already. You apparently have a bad rectifier, from the information in the print out. The diode pack is available separately, but I don't know the part number. Or you can get a rebuilt one. Be sure you get OEM parts (denso).

AHJ

Rectifier Plate Part Number: 27357-46290

I called up the Lexus Dealer, price is $215 but not available in North America. Alternator is $850 and also not available in North America.

Yamae

The situation is the same here in Japan. Toyota dealers don't handle the rectifier. They just replace the whole alternator.

But the rectifier is available at Denso parts offices. According to my friend who runs a small company which fixes alternators/starters, it is quite seldom to see dead rectifiers. But failed batteries that had a internal cell short circuit sometimes cause a dead rectifier.

AHJ

I took out the generator (correct term) and tested the rectifier. The results were not as specified.

Negative Terminal to rectifier terminal:
- Ohmmeter's negative on negative terminal, positive on rectifier: 250 ohms
- reversed: 400 ohms.
One of the above should have been infinity / very high

Positive terminal to rectifier was as required.

I saw a rectifier on ebay for $30 + but it wasn't Denso. There is actually a Denso facility in Mississauga but they only talk to wholesalers. I have sent an inquiry to them and they tell me that they have received it and will be replying shortly. (They did not mention anything about it being very important to them - I think that fad's been thrown out the window). Denso did point me to a website (Autowholesalers) that had a re-manufactured alternator for $125 so probably about $200 Canadian by the time I get it.

My plan is to take it to the alternator/starter shop close by and have them repair it then just keep a lookout for the Denso.

I will post some pictures soon.

fixmiester

Not sure where you are getting your information ; the rectifier pack consists of six diodes, and each has to be tested SEPARATELY . BTW, This is NOT a generator: it IS an alternator.. If any of the diodes is open or shorted, the whole pack must be replaced. May be more feasible to get a rebuilt one.

AHJ

I got the Rectifier and brushes/brush holder changed for $70 plus pick and drop service as its relatively close by. I was back within an hour.

They tested the generator and showed me a ripple on the oscilloscope.
They took out the rectifier before they tested it and showed one of the diodes as a short.

They showed me the brushes also and the height was about half that of the new one which wasn't ND and looked lighter but I went for it anyway.

If I ever have to do it again, I will mark the top and bottom because I had a hard time figuring it out. The bolts are not going in all the way. The top one turned out to be a stud with threads on both sides. Not easy for me.

fixmeister: Toyota Motor Corporation's Repair Manual for Lexus LS400 1996 calls it a generator.

Yamae

The name alternator is coming from the alternating current generator.

fixmiester

They can call it whatever they want, but that doesn't change the definition. Almost any search will show the same distinction as here:
http://www.allpar.com/eek/alternators.html

AHJ

Some pictures.
-The generator's located at the bottom left when facing the car.
-2 bolts to be taken out for the generator
-power steering pipe : 2 bolts on the left and one on the right in front of the oil filter
-3 attachments to be removed.
-- connector - hold clip at the back with finger . put flat screwdriver between connector and generator body and twist.
-- cable. held on with nut. It has prongs so remember how they go in.
-- the cable is attached to the body of the generator about 6 inches out. I unscrewed the 8 mm nut as I couldn't disconnect plastic clip.

AHJ

Here's a picture of the cable attached to the body of the generator after unscrewing the 8 mm nut.



unscrewing the 8mm nut was easier than popping the connector