Blower Motor Issues: 1996 Lexus ES300 

I do remember doing some lab experiments with transistors in school...maybe I'll dust off the old notes and do a refresher live on camera ;)

Was there a fuse under those two screws on the back of the module? Vbe on a darlington will typically be about 1.5 Volts (what you would see on pin 2).

Don't remember the complete circuit, but could probably "Meter it," looking for a Dead Short.

Noblesville here!

Sadly not totally rust free rick, she's got a bit of rot in the rear quarter panels, but nothing scary. I bombed it with Fluid Film and called it good for now. Might do something a bit more substantial in the spring. The underside of the car though is surprisingly clean, subframe and suspension mounting points are clean as a whistle. The only unpleasant looking part on the entire underside of the car looks to be the fuel filler tube! I had previously sold a '00 Maxima (this Lexus is its replacement), man that thing was a rust bucket. Lower radiator support was swiss cheese! And this was a car that was 4 years newer and only had 142k miles compared to the ES300's 206k. To be fair the Maxima had spent some time up in Michigan.

It's actually a clever design, as the car still had low and high fan speeds even with that amplifier not working. On other cars you would most likely lose blower operation completely!

motoYam82 That is very true! I hadn't thought about it that way. :)

I found my old lab notes from circuits class...will put together something soon!

Yo Eric! No, not PWM. This is an old-school current-controlled transistor pair. That's why the voltage didn't go up much on that control wire as the fan speed increased. I'm gonna go back to the physics lab notes to figure out why my amp clamp was showing reverse current in the final experiment haha

What if you turned your Ampclamp 180 degrees on the wire? By the way your brother bought himself a beauty !!!

The bipolar junction transistor "pair" are likely combined inside the big TO-3 package and called a Darlington transistor. "Modern" design would operate like SMA suggested, using PWM on a MOSFET.

Yeah I'm jealous! I call those cars "Golden Age Toyotas"

Yes, MOSFET's! A mouth full: "Metal Oxide Semiconductor Field Effect Transistor. " Way different operation compared with Bi-polar transistors. If you handled them incorrectly, you would destroy the "gate" and that was it! Needed a new one. Don't touch the pins! ha, ha

agreed, these are bipolar power transistors (current amplifying), not MOSFETS. Now I'll go read some old lab notes and review this stuff...it's been a while!

When are you going back to the soviet block? Russian Roadtrip?

Quite possibly you could...but finding and ordering that Darlington-Power-Transistor is probably more expensive than throwing in a 6$ spare part. The Transistor they used looked pretty standard though, so if really the Darlington-Stage broke in that thing, you could get the the part to work again. If it's the capacitor or one of resistors insisde, you might be out of luck depending on the case construction.

James thanks for the tip. The previous owner had serviced the transmission with fresh ATF and filters on a pretty regular basis. Fluid looks good, shifts better than most new cars I've driven. I will keep that in mind though!

james barnett the Needle light burning out is a known problem on the ES & LS series of the early 90’s . For some reason the LED’s burnout.

*200k

Great question! I am curious myself...too bad my brother took the parts with him!

Yes, but not a conclusive test. (I have to go back over 40 years to think of that xister internal circuit.) Even though a FET uses "charges," to pinch off current flow, FET's can be checked with a vom, but a totally different test is used. (meter is used to "charge" part of the xistor, then your body is used to discharge it, while monitoring other pins. ) I would have to look that up to test one now.

A speed sensor problem could cause hard shifts for sure, but sounds like you have some bigger problems now. Take it to a mechanic.

Look up darlington transistors and you understand how that circuit is operating in the medium blower speed modes.

Yeah I think it's only from neglected maintenance.

siucbet, my reading online points to several things: clogged PCV on cars that see mostly short trips, and some mentions of the heads running quite hot on later cars due to various claims (restrictive exhaust, emissions related things). Toyota saw fit to install a factory oil cooler on the 3MZ that followed on later Toyotas/Lexi. But if you simply change your oil as needed (severe schedule for cars that do short trips) and preferably use a high quality synth/synth-blend, and maybe check your PCV valve every once in a while, the 1MZ is a long lived beast. Apparently they run pretty rich fuel maps from the factory on the earlier cars so they're a bit 'dirtier' than most and somewhat thirsty, but I'd argue this also makes them less susceptible to knock issues from poor quality fuel, etc. and probably plays in a role in their excellent longevity.

gtemnykh DummyProof: It is hard for Toyota to make a car that is dummy proof. Follow scheduled maintenance and use Toyota Parts. Not changing oil on schedule can lead to sludge which can lead to PCV blockage. Even when it does clog just use some throttle body cleaner to clear the passage to and through the plenum and change the PCV valve. Poof, you are done. A PCV valve from Toyota will last 120K miles or more and a PCV valve from Fram will last 60K miles or more. If you do not put the proper octane in the car then it will knock but the manual clearly states to use 91 octane. Lets remember Toyota had their engineers spend many hours setting the stated octane level. Consumers need to follow the manufacturers directions. The 1MZ-FE is good to run for 300K to 600K miles. It is one of the best V6 engines ever made.

For what it's worth, I think mine has been run on regular 87 octane for much of its life with no undue consequences (I live in a flat area at sea level). I tried premium for a few tanks and so no improvement in either fuel economy or engine power. I do use "Top Tier" gas to keep the fuel system clean.

Good for you. I have used 87 octane in mine before and my car started to knock. I tried 87 octane in northern Illinois and central Louisiana and my car stared to knock in both areas. I went back to 91 octane or higher and my car ran normally again.

I know right? I'm jealous!

Magic

Magic yeah I need that right now. I can’t see how to compress the connector or take screw driver and pry the tab super frustrating any suggestions

@@jonathandrager8149 honestly this was 6 years ago so don't remember the details...try a pick