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Lets see if there are any Sherlock's out there to solve my 92SC400 mechanical crimescene... Problem: No heat incoming when car is at low rpm. Info: 1. New T-stat (factory temp 82C) 2. At cruising speeds (or rpm above 1500) - perfect temp control. 3. Engine coolant indicator on instr. panel is normal (ie. mid-way between Hot and cold..) 4. Rad shows some signs of deterioration (but this should not be factor) 5. Coolant level in reservoir is just under half full (on most cars this is normal ...) 6. When I slow down to idle, temp of air blowing in goes from warm to cold slowly (ie. 10 - 20 seconds) almost as though the coolant through heater core is stopped and warm air thus becomes cold... that's all, let me know if there are other pieces needed to solve this puzzle thanks!

Good luck. Hope you don't find many big items - cause .... well, welcome to the world of Lexus part and service pricing.... or - through the help of this forum, you could save thousands (literally) as I have.

Yeah, I hear ya - but the mechanical engineer in me just wants to pour on the PM (preventative maintenance) ...and yah, I'm ok to let the dealer take care of the current problem O2 sensor on the passenger side - but I'm going to pick up a recent service manual I ordered to see how difficult it is to replace myself. With Lexus dealer rates getting so high - currently at about $100/hr - I have no problem taking 3 or 4 times as long to figure out the solution. Afterall, it's not rocket science and with good mechanical aptitude (or really just interest) owners will probably take more care in doing their own fixes!! On that note, I'll stop before I go on to complain about the rates!!! he he , and thanks for the tips.

Good point about the cable, and mine seems a bit rough too when shifting ...I'll pay close attention to it to see if it warrants the extra cost. Something I noticed tonight was a badly corroded grounding cable underneath my car on the driver side (just above the exhaust pipe near O2 sensor). I'll get it changed too... maybe this has been causing my O2 sensor grief. Are there other cables in the area to consider?

Ok, so if I could summarize the items to do while having main seal replace: (ps. I've got 150,000 miles on it...) 1. rebuild tranny (major, alternatively just seals at end) 2. replace torque converter and drive shaft seals 3. replace EGR pipe (apparently they can crack with age) 4. ? 5. ? Any other items in this general area guys ??? Tranny filter ...? Not sure if oil pump gets removed in this work - if so should I replace that ...? thanks.

Hi everyone, the rear main seal on my 92 SC400 is leaking and it's a bigger job than I'm equiped to fixing. The cost is a real stinger - ie $1000 when the seal is like $20.. My question for you all is, While the transmission is removed and the dealer has access to the front of transmission and the rear of the engine- Are there any other seals or components which you recommend replacing while having the access to do the work? thanks for your advice,

Thanks, but I just noticed that only volume 1 is available .... What is the difference between volume 1 and 2? I'm mainly interested in the engine components .... Also, it's like pulling teeth to get these manuals from Lexus ... thanks

Hey there LScott, that adobe download is very detailed. What manual did you get that from and where can I purchase it .... (ps. I'll need it for my 92 Sc400) thanks,

Still only throwing code 28 (passenger side O2 sensor). Dealer wants $300 for sensor and $200 for install. I'd rather get Denso or Bosch myself for less and install ... but not sure where wire and harness go through floor. Do I need to rip up the passenger carpet and will I have access to the connection? I'd feel better with some words of advise before I venture into this ... thank you,

Well, I cleaned the MAF (wasn't very dirty - just a bit dusty),,, and now code 24 and 31 are gone (fingers crossed). Now I'm left with only code 28 - main O2 sensor signal. I get very consistent results here when it comes on. Basically, after 5-10 minutes of driving it comes on... and then after shutting down and re-starting check engine light it will beon if still warm, but if more time is allowed for cooling (20 - 30 mins) then it will start without the check engine light on (but code still in ECU of course). Curious if this implies anything such as faulty wiring or ground, ... rather than the sensor ? before I spend the money on the sensors ... Also, I looked and looked, and looked somemore - is there a tutorial somewhere on how to change the O2 sensors?

Well, got the results from the lexus dealer - and get this ... apparently the error code 51 which I obtained form the "wire jump system" didn't register for them. Instead they found 3 new error codes - #24 (air intake temp sensor signal), 28 (no.2 oxygen sensor signal), and 31 (vacuum sensor signal). YIKES - signal issues! and probably related to one another. Now I've got some homework to do because I know there is lots of info on these already on the network and I can see the dealer running this up to $1000 in no time. Anyone who knows of these are welcome to share their thoughts. thanks

That sounds probable. It was actually the traction light that originally came on - and then minutes later the engine light.... But after a week or so - they both came on together after getting reset each time .... Quick question - I'm pretty hands on - is it fairly straightforward to remove and reposition the new sensor into place... ????? thanks,

Nope - not really. I've been meaning to take it in to the dealer - perhaps in the next day or so .... I got a feeling it's going to be a bit of a cluster whereby they poke and check for some goofy signal and end up with 2 hours labour and who knows what component (or loose wire?) they come up with ... Gee - can you sense my sarcasm and cynicism ... Will share if I get good feedback.

Ok - here's the status. New rear tires - and still have problem. Although now I notice it's the check engine light that comes on first and then the trac light follows... Also, after resetting today, it was gone and then while going down the highway I put the A/C on - and instantly the check engine and trac light came on ... Anybody have ideas how to trouble shoot this (error code 51)?

I had identical effects when putting new ignition cables. I mixed two of them up and the car ran just like you've described... Had any cables changed lately ??? good luck ...

Good morning, Help - C'mon - Any takers on this error code 51?? I've tried clearing this alarm by disconnecting the battery and/or fuse ... but still have the trac and engine light come on after a few minutes of driving. I'm putting badly needed new tires on tomorrow and we'll see what happens then. Is there any point to do a brake line and transmission fluid flush ...? I'm dreading going to the dealer - and you all know why - $$$$

I've got a 92 SC400 with the trac light on and check engine light on. Doing the wire jump on the diagnostics I get a error code 51. From what I can read this indicates a switch condition signal. Note: I've noticed rough cold starts if the car sits for 48 hours. 1. Does anyone know what switch condition signal means? 2. How to trouble shoot the cause any further? 3. Is there any harm in driving for several days with the trac and engine light on? pleeeaaase help, :cries: and thanks in advance!

Hello guys, I guess I'm "joining the club" with the TRAC and ENGINE LIGHT issue. Perhaps some of you can help troubleshoot my problem. The light just went on today - but it occured after I did a rather immature (but devilishly enjoyable!) brake torque with a beauty of fishtale. 1 minute later my lights came on due to some side effect of doing the burnout. Also, my tires are due for changing (which is why I've spun them for fun today) and I was curious if new tires on the front and very worn tires on the back could cause an inaccuracy in the wheel rpms from front to back and if this signals the TRAC and ENGINE LIGHT to come on.. thanks for the help,

Yikes, you guys aren't making this easy on me. The more I read the more I think I should keep that which makes my smile every time I drive it (the SC!...) I've checked the GS400 over a little better and I think the paint on my 92 SC400 is actually in better shape - glossy jet black colour ... and at least I know what I have right now with my car and the good PM done on it ... and it may be 15 yrs old - but it still turns heads when I've got her all washed up! I'm just not sure how much longer this thing will go being at 250,000km ...

Yeahhh I know.... my hearts with the SC - but its coming up on 15yrs old and nothing lasts forever ... The GS is in real nice shape, and being newer with same 4.0L (newer version) it's probably a solid reliable car,,,

Hello, I've got a tough decision to make .... need some input. Have a chance to buy a fine looking 1998 GS400 (1 owner, black, 180,000km) for $13,000. Currently have a 1992 SC400 (2 owners, black, 250,000km) - and in the last 50,000km replaced some key typical items such as alternator, power steering pump, starter motor, antenna, battery, and have used good quality synthetic oil for a long time, and oiled the underside of the car every year. Is the 98 GS400 comparable in quality and luxury as the SC400 - and how much should I be able to get for the SC400 to offset the $13,000 cost of the slightly newer GS400??? You see, if I don't get very much for the '92 SC400 - then I may be better off keeping it for the long haul because of the care I've put into the maintenance of it... Pleeeeeeeeaaaasee share your ideas, and any feedback on the '98 GS400. thanks for your help!!

Okay, I see a solid concencus ..., thanks - and I'm right on it. I'll be taking it in to get it worked on - I'm expecting this to run about $300 - $400 for a proper job (max size is 1" x 5" ...)

Hello, I've got a 92 SC400 with some rust starting in the rear right panel (below the little fuel acces door) and I was wondering is it better to have this rust removed/painted now while it is 1 inch x 4 inch or is it better to let it go a bit and then work over a larger area which is partially corroded but not yet visible ..? might be a dumb question - but thought I'd ask ... thanks

I don't think it has anything to do with the fuel filter... I'm guessing there is unburned fuel getting into your exhaust and then it's cooking in there causing it to get real hot .... JZZ say's check the coils - and if they're not right then you may get what I mentioned ... Try the ignition wire test - while idling pull each one at a time to determine if some aren't working ... this trouble shooting will get you closer to the problem ... good luck ..

I changed my alternator - 92sc400 - did not touch the rad. I only loosend a few items on the fan so it could shift a tiny bit - just enough to orient the alternator the right way to pull it out. Mind you, hanging over the front of the car like a monkey - holding on to the 15 pound weight isn't easy after a while of fiddling!