curiousB

Maybe air pockets in coolant? Is coolant low? Maybe a leaky or damaged head gasket is letting coolant into the cylinder and being vaporized out the exhaust. Otherwise I'd check thermostat.Maybe just change thermostat. They are cheap enough and simple to swap out. I doubt the fan would be a big factor as when you are driving airflow is fine. Fans solve the issue when your standing still in traffic. If the needle is bumping around while driving at a contant speed ignore the fan issue for now.

Overkill in my mind. I just change pads if the rotors aren't unusually scored.Once rotors gets scored up (actually more commonly warped) I just replace them with new ones. In 130k miles I've changed pads 3-4 times and rotors once on each wheel. What I saved in dealer labor to machine the rotors more than paid for the new rotors over the past ten years. Maybe if I was driving on a track at 150+ MPH and hard braking into turns I'd want pristine rotors milled in place to null out any stackup error of tolerances. I don't know about you but my lumbering comfy couch LS doesn't get a lot of track time...

Richard, Some really terrific work here and to the benefit of others down the road. Nice job!!!!

Shes a beaut but she's a senior citizen too. Don't be surprised if she needs a knee or hip replacement down the road. Without health insurance you'll be footing that bill and deciding repair value vs. value of car tradeoffs. Don't get overly emotional, its just a car.

..."This all started after the alternator died and I had it replaced. "... It happened when? immediately as you picked it up? Within days,weeks, or months of hacving it done? First option is to take it back to guy who "fixed it". Is belt on? Is charger wire bolted firmly on side of alternator (disconnect negative post of battery before you get down there with tools)? Battery post clean and tight?

7 V across 22Ω resistor is 318mA which is very excessive key off current. You want to be down under 50mA. You should read 1.1V or less across the resistor. If you have tried all the fuses maybe the alternator is at fault try the procedure here: http://us.lexusownersclub.com/forums/topic/75789-1999-ls400-and-obd2/?p=461626

A couple comments to add to the story. Battery current drain (called key off current drain) should be well under 100mA and probably under 50mA. The issue is when to measure it. Many of the car circuits stay powered up for several minutes after shutting car off. Also opening a door or hood can restart the delay sequence. Lastly an open hood can also defer ECU from dropping into lowest power state. So I would suggest connecting your Ammeter in series with the battery. Close all doors. No key in ignition. Spoof the hood switch to think it is closed and then wait half an hour to take a measurement. That is likely the true key off current and the one you want to see quite low. Now if it doesn’t measure well under 100mA try popping out fuses one at a time to localize the rogue current drain. Be patient. Each time to open a door you likely reset the power down sequence so need to wait to take a new measurement. Lastly power drain can be due to a failing alternator. The stator diode array can become leaky and when that occurs it becomes a current drain on the battery that is not behind a fuse or a switch. Simple check for this is to disconnect the charge line of the alternator and see if key off current drain noticeably drops. Happy sleuthing. These electrical problems can be tricky and subtle. Be patient. Just try one variable at a time and move step by step.

I'm guilty of not changing brake fluid in 40-50k miles. How much of a pain is it to do this? I bought fluid 2 years ago to do it with (still sealed closed). Should I throw away and buy new?

1. When I remove the coolant from the engine block do I have to jack up the car? - not to drain the coolant, but I found it easier removing the alternator, then loosening the PSPump. The procedure says the other way around but I found it much easier with Alt out of the way. 2. In order to access the flywheel area does the car need to be jacked up? - No but I don't think you can do this easily without jacking car.Why the big hesitation? That is the least of your worries. 3. If so when working on the timing belt do I jack the car back down so that it is on level ground? - I did the entire procedure on ramps. Had to stand on a small box for some things. 4. The service manual mentions removing the camshaft pulleys? I don't see why this would be necessary? - This is to change the oil seals under pulleys. Since you are 95% of the way there many recommend doing it for good measure. I didn't do this and haven't had a problem. You should seriously consider a new water pump while in there. Not too expensive and just a good idea. Be sure to get the gaskets, FIPG material and new WP o-rings for this before or you won't be able to finish. One tip, be organized, bag parts and write on them where they go. For things with multiple bolts of various length draw a picture of which goes where. Saves time on assembly. Take pictures along the way as your digital bread crumbs. I have 35,000 miles on my TB now so I guess I did it properly....

My 2003 LS430 ultra all of a sudden no longer can play cassettes. It started when the adapter ( cass w/ aux wire ) just popped out. I bought another and it did the same thing. I tried a few cassettes and they too all popped out. I have about 100 tapes and over 200GB of MP3's. I cleaned the inside w/ alcohol, blew w/ air also. Any ideas? AK47 on standby... Maybe it dislikes your choice of music?

Common problem on these cars. Check the coils. That is 80% likely the problem. As Landar and SRK suggest, it is not too hard to self test. The car will continue to run rough when you disconnect the bad coil (since its not doing any good already) but when you disconnect the good coil the engine will die. Put a new coil in and you're back on the road, no gas smell, no red hot catalytic converters, and all the power you need to secure a handful of speeding tickets.

The car was running with me applying a little gas. I was doing so to keep the revs up to stop the car stalling. Once it was warm it ran fine. This is why I thought to replace the IAC valve and coolant temp sensor (to stop the cold stalling). A damaged ECT sensor is typically open circuit or infinite resistance. The ECU will see that as cold engine and adjust fuel mix to richer to get it running and warming up. A warm sensor is more closer to a short circuit (100-300 Ohms reading). So the symptom I would expect for you is that it starts easy when cold (since ECU thinks engine is cold when it is) but starts very poorly when warm (cold ECT reading makes ECU send too much fuel to warm engine and floods it). You have the opposite which is strange. Maybe by some fluke you have a shorted temp sensor although the typical failure mode is to blow like a fuse and go open circuit. http://www.autozone.com/autozone/repairguides/Lexus-GS-SC-1998-06/Coolant-Temperature-Sensor/Testing/_/P-0996b43f80382b2a A voltage reading on an unloaded battery doesn't mean too much. What is voltage under some load? Turn on headlamps with engine off. Does battery sag to very low voltage? That can mean weak cells and/or poor connections. Undo battery connections and clean up all mating surfaces with wire brush. Reconnect and ensure clamp bolts are good and tight. If you can wiggle the connector then they aren't tight enough. Starters draw a couple hundred amps, you won't pass that kind of current on a loose connection. If the connection cleaning doesn't help any it points to the battery. Anyway worth a few minutes effort to try the clean up connections before dropping $100+ on a battery. No harm in an ECU test if it is free. I just wouldn't buy one yet given the preliminary state of diagnosis so far.

Belt noise is likely either AC bearings or maybe the AC clutch mechanism. Clutch may be repairable on its own but it may be hard to source since that part as it is often sold with the compressor as a complete unit. Not sure about the ticking but since its a '98 maybe you just live with it.

Firstly I began by replacing the coolant temp sensor. It still ran after this but still stalled when cold. Got given a replacement IAC valve (with a different part number but was assured it would be okay) so I installed it. The car would not start with the new IAC valve in and just clicked like a flat battery but I had loads if juice and even tried jump starting of another vehicle - no luck.>>> can you start it with a light foot on the gas pedal? The IAC just allows some air to pass throttle plate to idle the engine. You can simulate this with a light pressing of the pedal.<<<< Replaced the IAC valve with the original one. Tried to start but still clicked like flat battery. >>>> you have either a dead or weak battery or loose/corroded connections to it. You need to fix this under any scenario. You shouldn’t need to jump start it. I would get this resolved and start knocking off issues rather than dealing with them all concurrently<<<<< I hooked it up to another car and managed to get it to jump start. Took it for a spin around the block, parked back home and then it wouldn't turn off. I removed the coil pack to kill it.>>>>>why did you do this?!?!?! Couldn’t you just turn the key off? Seems like you broke a connection doing this or have a loose/dirty wire/connection. I’d get some contact cleaner spray and clean up connections and retry. Back off on the MacGyver methods and get a little more organized<<<<< Since putting the coil pack back on it will not start. I bought a new IAC valve (with the correct part number) and installed it. Car will still not start>>>>The IAC isn’t the reason you aren’t starting. That is a red herring. IAC modulated idle speed. Try the light pedal approach and get it running before you dive into the IAC issue<<<<< I checked the codes and came back with a 51 - switch condition signal but don't really think this is the cause of the issue. Where to now? I thought perhaps that because I put the incorrect IAC valve in that I possibly have done something to the ECU? Can this happen >>>>>>>>>>>not likely, I would park this theory to the side for now<<<<<<<<<<<< My next best guess is to replace the ECU but I would like to know if anyone has better suggestions to try first? >>>>>>>>>>>bad guess. Try the items above first. Fix battery, get engine running by sorting out the coil pack problem, then go after IAC issue. ECU is expensive and you haven’t done any diagnosis that suggests it’s a good candidate to change out.No need to drop a lot of $$$ on a hunch. Be patient and methodical. Report back once car cranking reliably and if engine starts or doesn’t with a light foot. We can take it from there. My guess is you aren’t getting spark on at least 4 cylinders due to your coil unplugging mishap.<<<<<< Any help is greatly appreciated. You may have a fuel problem too but you have to get it back to at least starting for a moment before jumping into that one.

good stuff. Strange the sensor didn't trip a code but maybe it was just drifting out of spec rather than failed. 230k, just broken in! Had fun with mine when I rolled over 123456 a few months ago. Wife thought I was nutz....

Hi Billy, No P0115 to go with it? That is a faulty coolant sensor code. Low coolant and/or air bubble at the ETC sensor? Have any O2 sensors been changed lately? I saw one post where a generic (bank1, sensor 1) O2 sensor was miswired, the signal and ground reversed, causing a P0125 code. You'd think that would pop many O2 related codes as well though.

Why do you think this sensor is bad? What codes did you get? I suggest an O2 sensor socket. They are 6 point so the sensor doesn't strip on removal and have a keyway for the cable. They get pretty stiff after many year and thousands of heat cycles. You'll probably need a breaker bar too.

Is the click coming from the starter motor? Is it the solenoid on the starter motor? Is it a single click or a rat tat tat noise as you crank. That could be good news. If that is engaging then problem must be in the high current wiring to the starter. Maybe a loose bolt? Starter motors draw a lot of current so those heavy wires need very tight connections. Be sure battery terminals are torqued down good and tight and metal to metal connections are fairly clean before torquing.

Welcome home Billy. Nice looking condition for a '99 with 228k. You can probably handle a TB and WP in your sleep! While these cars are expensive new I suspect over their full life they are a real bargain.

I lean toward ignition as first item as well. Fuel starvation is more of an engine under load issue. Rev'ing an engine in park is not much of a load and doesn't tax the fuel system much. Ignition on the other hand is RPM sensitive but not much to do with engine load. The simple test is while engine idles. Unplug one side coil. If engine stalls replug and restart engine. Try the other side. The theory is that if one bank is dead or poorly working disconnecting it will make little difference to the idling. A good bank though once detected should be very noticeable. No parts required to try this.

The mirror glass pops out by rotating upward the bottom edge. It's a plastic snap fit so I have been too nervous to force it for fear the snaps will break instead of popping out. Then a well intended maintenance becomes a $1000 Lexus headache... I subscribe to the view, if it ain't broke don't fix it...

I suggest if anyone is having this O2 sensor related problems to pick up an OBDII PC interface (USB) and software to run on your laptop. You can get real time graphs of the sensor output. You can compare primary O2s to each other, primaries to secondaries and so on. I had my wife drive around while I looked at the outputs and different comparisons. I couldn't have solved my problem below otherwise.

Reread the instructions. This only works when neither A nor B trip odo is showing. It will never work with either showing. That is the point of the first instruction: - >> Push the “ODO/TRIP” button to change the (trip) display to blank.

Ah perhaps you mean you want to know how to do it yourself.. To reset the data, perform the following operations: Push the “ODO/TRIP” button to change the display to blank. Turn the ignition switch off. Turn the ignition switch to “ON” with the trip meter “RESET” button held down. Keep pushing the “RESET” button for longer than 5 seconds after the ignition is turned on. After the above operation, the master warning light comes on, a warning tone sounds and the above message appears to inform you that the engine oil maintenance data has been reset. (U.S.A. only)

OK go ahead and do it.