George Z.

I recently had my alternator go bad and whenever I'd run my A/C for a long period of time (i.e., 1 hour or more), my charging system was getting low. Long story short, I changed my alternator with another 100-amp one and my A/C and charging are just fine now. I also went ahead and changed both distributor caps & rotors with "O.E.M." dealer-parts from the local Lexus dealership. Now, my Check Engine light has turned on and it's Code # (P0340) -- DTC P0340: Camshaft Position (CMP) Sensor CKT Malfunction. I purchased a NEW Camshaft Position Sensor #1 (Bank #1 - Driver's side) & installed it, and the Check Engine light returned with the same exact code - P0340 (Camshaft Position Sensor #1 Malfunction). I checked the actual "connections" on the Camshaft Sensor and all the wiring seems to be perfectly normal & fine. The "symptoms" of the car are as follows: At idle in park after the car warms up and the idle drops to between 650-700, the idle has a little "play" in it and it moves up and down a bit. It's not surging badly or anything, but the idle is not smooth. Also, if you're in drive and stopped at a light with your foot on the brake, the idle does the exact same thing. When driving and moving down the road, the acceleration feels normally smooth and without hesitation. It's just at a complete stop or idling in park or neutral, it does this...? Any suggestions or ideas as to what can cause this? Could it be that when the initial alternator was going bad (with the A/C running) that it possibly "shorted-out" a section of the computer or ECM and it's not correctly reading this signal? Thanks a lot in advance for any help you can provide or suggest to me.

I just bought a '97 LS400 a few months ago with 147k miles on it. The car was in excellent (not quite perfectly-mint) condition but mechanically-speaking, it was and still is amazing!!! It's throttle response is definitely a bit "reserved" upon take-off, but mash the gas pedal and get the RPM's high enough (about mid-way), and the torque and horsepower will pin you in your seat and pull for a very long time. The car's ride is ultra-smooth and it's power has a sense of "finesse" to it. It pulls smoothly, its torque seems to be never-ending, and the gas mileage & fuel economy is excellent considering the weight of the car and all. I would definitely recommend this car to anybody. It's a great value and amazingly-engineered. I now have 151k miles on it and I couldn't be happier. I've done a few maintenance issues - but nothing out of the ordinary. I've also heard and been reading that these cars are very well-known to last up to 300k miles with no problem - assuming you keep up with common maintenance procedures and routine oil & filter changes - whether you use conventional or synthetic motor oil. Hope this helps!!! I can possibly help address your concern of "reserved" acceleration. Part of that may simply be due to the conservative ECU throttle calibrations these cars received. Seems the initial travel of the throttle pedal doesn't generate a whole lot of action, making this gem of a V-8 engine possibly feel weaker than it actually is. You'll get accustomed to it quickly. The truth is, this soft calibration also contributes to a smooth driving experience which was clearly of paramount importance to the engineers. No one wants a Lexus with a 'herky-jerky' on-off type of throttle response. Rest assured though, if you continue to ring up the engine room and step down further, hitting the transmission kick-down point, the car WILL get up and GO! (assuming it has no issues of course). My '92 LS, while in excellent running condition with no mechanical problems, was notably sluggish feeling until about mid-throttle. Smooth? Yes. Incredibly responsive? No. Now, the 99 model is a whole 'nother ball game. It has variable-valve timing, drive-by-wire throttle, lower internal trans gearing for off-the-line snap, plus the engineers spec'd significantly more aggressive overall throttle calibration, at least in direct comparison to the first-gen car. I can't comment specifically on 1997 as a model year because I've never driven one, but you're still talking 260HP which should be enough to Git-'Er-Done for all but the most addicted acceleration junkies. Now, I will say if you mash the gas on a 1998 - 2000 model they just plain fly. 290 conservatively rated horsepower, and 300 lbs. of torque. I basically grew up and spent most of my early life on the drag strip so I have a very good understanding of physics as is pertains to acceleration. Also spent many late nights on chassis dynamometers. We're talking 0-to-60 in the 6's, and the potential for mid-to-high-14 second quarter mile times at almost 100mph for a strong running example (search these forums for confirmation... and you'll definitely find it). Not too shabby for just about 2 tons of leather-lined living room being hurled down the road. My 5.7 liter Corvette-powered Trans Am honestly isn't much faster (mid 13's... and a whole lot louder), and we won't even discuss the difference in ride and overall build quality. I'm sure others will also share their opinions regarding your noted observations, but hope this 2-cents worth helps. Overall they are definitely some of the finest automobiles ever built - I doubt you'll be disappointed.

I tested the car's charging & battery with a volt meter and with the car off, it's right around 12 volts. With the A/C fan level on level 1, the charging is in the high 13's and almost 14 volts. However, with the A/C fan level on level's 2-5, the charging system is back down to around 12 volts. The interesting thing here is the fact that I can turn the A/C off, but turn ON the headlights, radio, wipers, dome lights, etc...and the charging is perfectly fine at around 14 volts or a hair-shy of 14 volts. I have done the following today: The cabin air filter has been changed. The one it had in the car was terribly worn out and filthy. The problem has not gone away though. I am going to try to install a used blower resistor / relay from a local junkyard. I will then run the car for more than an hour on a high level on the fan motor of the A/C and see if the problem will get taken care of. Also, I have replaced the serpentine belt with a brand new Gates belt from O'Reilly. The belt that came out of the car looks like new, so I am now starting to think whether or not the accessory belt tensioner (which is "spring-loaded") could possibly be allowing the belt to "slip" over all the pulleys...? I should have an update for us all by this coming Monday. Thanks again for your replies and helpful advice!!! Let's keep this wonderful forum site going strong...

I have a 1997 LS400 and I've had a problem whenever I drive the vehicle for more than approximately 45minutes to 1 hour, the A/C blower motor weakens and doesn't blow through the car's vents "accordingly." What I mean is that when it's on "level 3" (out of a high of 5), it barely feels like a "level 1" (and when it's on "level 5" it'll barely feel as if it's on "level 2"). When this happens, the air coming out (albeit it's a lot less) is still cold and it NEVER gets hot...just the speed and strength of the blower motors WEAKENS. When the car is turned off for a little while (between 30 minutes and 1 hour), and then restarted, the problem goes away and the A/C system functions perfectly with normal fan speed and strength accordingly. That being said, I had the alternator checked today and when the A/C is on "Level 1", the alternator is putting out full charging strength. However, if the A/C fan is put on any level between 2-5, the charging is very weak (barely at 12). I went ahead and replaced the alternator as it was determined to have gone bad, and I replaced it with a new alternator. The problem still remained!!! Nothing changed. Now, with all this being said, my "battery light" in the dash (the one to let you know the charging is on the WEAK side) has NEVER come on. Nor has the car stalled or done anything out of the ordinary. My overhead map light did flicker last night when I drove the car, but neither the headlights nor any other lights have been flickering in the vehicle. I was told this could possibly be an A/C blower motor "resistor" that's going "faulty" and when the fan speed is higher than level 1, it's pulling too much current from the charging system, hence draining the alternator and showing the charging level to be on the low side. Does anybody have any experience with this similar problem in the past? Any help? Please either reply or call me (713-459-6411) as I'm needing to fix this by tomorrow (Saturday 5/23/09) withOUT taking it to the dealership. Any help you may be able to offer or throw my way is greatly appreciated !!!!!

the 3000mi oil change is a myth. i run ~8k mi between changes, bosch filters and Mobil1 full syn. 5w-30 (switching to 10w-30 due to the weather in my region). I guess my question is more regarding whether starting to use Mobil 1 synthetic oil in my '97 LS400 is a good idea if the car has never been used to synthetic oil and it's already got 147k on the clock?

I am new to the forum and I just purchased a 1997 Lexus LS400 with 147k miles. The car is in excellent shape and runs like a champ. I've already put 2500 miles on the car with no problems and I'm also getting excellent gas mileage. I have traditionally used Castrol GTX 10-30 (conventional) oil in all of my cars - both domestic and imports. My questions is as follows: would you guys recommend me switching to Mobil 1 (full synthetic) motor oil & going 5000 miles between oil changes or sticking with the conventional Castrol 10w-30 and changing it every 3000 miles? When a vehicle has this many miles, and assuming it's always had conventional oil, is it harmful to change it to full synthetic? Are there any possible ramifications or repercussions in doing so? I am very pleased with this LS400 as it's my first Lexus to ever own and drive. It's truly a pleasure to drive and travel in. I will soon be in the market for one of the newer '07 LS460 models. Any help will be greatly appreciated. Thanks in advance for all of your help. PS - I live in the Houston, TX area where our summers are brutal with lots of heat and high temperatures. Thanks again.

I just wanted to follow-up on this thread and let you know that I changed the "3rd-tail lamp" light bulbs (which are bulb #921) and when I put 2 Sylvania bulbs from AutoZone and I started the car and depressed the brake pedal, the light no longer stayed illuminated in the dashboard. Apparently, the 2 bulbs which were in the 3rd tail lamp brake light were very cheap ones (that were still working, might I add) - but they seemed as if their design had very thin wiring or elements that were sending an inaccurate signal to trigger the light to remain on in the dashboard. Hope it helps & thanks for all of your replies !!!! George

I have a 1997 Lexus LS400. I recently had the "Lamp Failure Sensor" trigger the light that turns on in the dashboard and I found out that it had 1 brake light and both license plate light bulbs burnt out. I changed out all 3 bulbs and I confirmed that there are NO more light bulbs that are not functioning or turning on in the car when examining it in the night-time. However, every time I turn the car on (which is only in the night-time) and I have the "automatic lights" turned on, as soon as I depress the brake pedal, this Lamp Failure Sensor triggers the light in the dashboard every single time. Any suggestions as to whether this light keeps returning? Do I need to swap out & change this "Lamp Failure Sensor" which I found it is located in the left side of the trunk compartment. Or is it possible that some of the brake light connections are possibly corroded and sending out this signal to trigger the light to come on in the dashboard (even though all the lights are working properly in the car). Thanks in advance for your help. George