Nole65SG

I replaced the gauge cluster on a 92 Lexus SC300. The needle lights on the old cluster were not working and the speedometer and tach only worked intermittently. I found a used cluster and had it installed. The needle lights now all work fine and the speedometer and tachometer both appeared to function properly. However, by the end of the day the speedometer and tach were back to zero and not working again---or working only intermittently as in the past. Needle lights, however, are fine. Any ideas what the problem is with the speedo and tach and how to fix? Thanks.

An led for duty cycle. I see. Never was exposed to that sort of thing. Cool stuff. Ok, so the output for injector pulse is staying on. Swap the ecu. Let us know how it turns out. I guess if the engine could stay running with the injectors always open it would smoke like mad. Kind of interesting it even stays running though.

No you should not need to change the injectors when you change the ecu as long as the ecu is the same model number/model year. Avoid a 97+ ecu. The rest should work. But consult the parts supplier to be sure.

I thought the vvti Sc3's had 6 coils. They are 3 coil wasted spark? News to me...

I will let you know the result. Yes, the smoke was tremendous and the fuel smell stifling. The engine locked up very soon thereafter. Tremendous pressure built up in the cylinder. Gas shot 8 feet in the air when pressure was released. Not your typical repair!! Thanks for the info on ECU.

A pulse light is used at the injector connector to see the duty cycle pulse width. If it is always on the injector is always spraying fuel. It has nothing to do with coils. Only things involved are wiring, ECU. Sounds like maybe a short to ground somewhere on the wiring harness,or ECU. I'd do some pinouts from the connector of the injector to the ECU for conitinuity and continuity to ground also.

Thanks. We are on that track right now.

Has anybody had a similar experience...I have a 92 SC300. The pulse light is staying on causing the fuel injectors to stay open and a steady stream of fuel into the cylinders. I know for sure that the last three injectors were constantly open. As a result I had billows of smoke out the exhaust and of course the car could not be driven. It appears that the main computer is malfunctioning causing the pulse light to stay on. Anybody had such an experience and did the fuel injectors have to be replaced too?

There are three cables going to the throttle body (automatics). One goes to gas pedal, one to cruise control, and the last to the transmission. It has an adjustment at the throttle body bracket. The cable stretches over time. Do the tighten up!

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Thanks!!! Its worth a shot. Im going to give it a try.

I had a similar problem and I adjusted the transmission kick down cable. You can get a used ECU from recycling yards or off Ebay.

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Very Interesting. Nobody has told me that before. Where is the cable and what kind of adjustment did you perform.

Had trouble getting auto transmission to upshift from third to overdrive consistently on a 92 SC300. Overdrive solenoid tested ok. Problem in ECU sending signal to transmission. Anybody have any experience with new vs. rebuilt? Can get a new ECU for $800 w/o labor. Anybody know where I can get a better deal on the part? Thanks.

What all does the fuel pump ECU do in the SC300? Anybody know? Also, where can I get the technical info. for its removal and replacement? Thanks.

Well...the first thing I would check would be the air flow sensor near the intake.  Next, I would check the throttle cable and ensure that the cable moves freely w/o restriction.  From there...check the throttle body to ensure that throttle plate opens freely.  While you're at it...spray some throttle body cleaner into the plate to get rid of the carbon buildup.  Wipe off what you can reach.  Don't worry about the stuff you can't reach,...as it will burn off anyway.  (Just spray a bit of the stuff...you don't need to spray too much). 

When you start the car (due to the throttle body cleaner)...your car may run like crap intially...as it is trying to get rid of the cleaner.  Don't worry...but start the car and give it a little gas to help get rid of the cleaner. 

See if the problem stays. 

I would also recommend changing out the tranny fluid (and replacing the transmission filter) if you had not already done so.

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Thanks Ill give it a try.

I have a 92SC300 auto transmission. I was at a stop and my RPM's suddenly started rising rapidly. I had to put the car into neutral and turn the key off. When I restarted, the car was fine. Also, over the last month, the overdrive twice didnt want to kick in at around 40-45 mph. Stayed in third gear. However, when I turned the car off and restarted, everything was fine again. A mechanic looked at the car and said he wasnt sure but it may be computer related. Does anybody have a similar experience or know what is taking place?? Thanks.

Thanks. Its an automatic. I think it was the overdrive button. It was in the "on" position. However, after pressing the button a few times in and out, I am no longer getting any problem. I'll just have to keep an eye on it.

Auto. Transmission. The gears shift smoothly from 1 to 2 to 3 but then dont want to go into fourth gear. Any similar experiences or have an idea what the problem may be? Thanks.

I would appreciate if anybody could tell me the location of the thermostat on a 1992 SC 300. Im spoiled with a 1969 Chevy Nova. Changing parts is pretty easy. Is changing the thermostat on the SC 300 fairly easy (meaning easy to get to). Thanks!!!!

My 92 SC300 acted in a similar manner. Did you check the fuel pump ecu? I bypassed it and the problem is gone. Be advised, however, that alot of fuel seems to be used up due to a hard cold start without the ecu. However, can always look in a salvage yard for another fuel pump ecu.

Thanks. Must agree. I had my radiator and thermostat changed and the shop put in a new thermostat from the parts supplier along with Dex Cool. Now I have a slight ping upon acceleration. Never had the sound before. Probably a different thermostat than designed for the car.

Appears from previous threads, its the Toyota Red Long Life.

What is the proper coolant for a 92SC300? Thanks!

Need a quality and resonable parts source other than the junk yard and Lexus dealer. Any recommendations where to purchase refurbished hub caps and other parts for a restoration project involving a 1992 SC300? Thanks.

As I understand, the closest Lexus dealer is hours away in Jacksonville. I worked together with the guys at Action Auto (focus on imports) on Gaines Street to come up with the solution. The info. I received on this board made the difference. Also, keep in mind Bill Cayson off of South Monroe Street. Even though his specialty is Chevys, he has been around. Knows cars well and is reasonable. I have him doing some work on the car as we speak. GO NOLES!!!!

It appears indeed to have been the fuel pump ecu. No more stalling. Thanks.

Research this forum seems to indicate either an Idle Air Control Valve or a Fuel Pump ECU problem. All of this assuming, of course, that a bad fuel pump replacement is not the problem.

My 1992 SC300 has a warm start problem. The car will start up and then after about 3-5 seconds dies out. The problem will keep repeating itself until 7 or 8 start attempts when the RPMs will finally remain steady and the car will not die. Does not happen on cold starts or while driving. Only after it has rested and while the engine is still warm.

Mechanic started off replacing the fuel filter and then replaced the fuel pump. Said the old pump was only delivering about 7-8 psi. Drove the car home and problem again is repeating itself this evening. Taking it back in the morning. Thinking could be another problem or a bad new fuel pump. Any thoughts or similar experiences? Thanks!