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Lexus LS: Problems & Solutions

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  • edinphilaedinphila Member Posts: 11
    When I start my 93 LS400 cold, the low coolant warning light comes on after a few seconds and then goes out anywhere from 10 to 30 seconds later. My AF level is fine. Any ideas?
  • sooners44sooners44 Member Posts: 1
    check the left hand trunk harness in the left trunk hinge the wires will stretch then break you need to add more longer wires and sodder together no butt connecting
  • pj2323pj2323 Member Posts: 43
    on my 1992 ls, the speedometer has suddenly stopped working on cool mornings. after the car warms up, and you drive it a few miles , it works again. is this the circuit board, or another problem?
  • pscmjpscmj Member Posts: 7
    I read in earlier postings about a problem with the cold idle speed on these vehicles. Did anyone come up with a solution? My 1994 LS400 with 77K miles wants to idle at between 1400-1600 RPM until it is good and warm. I bought the car used last April. When I took it to the local dealer service department to have them take a look at it they said this was normal and there was nothing they could do ... the fast idle speed is computer controlled. This is a very annoying problem and can actually be somewhat dangerous (my wife recently had an accident partly because she wasn't used to driving this car while it was cold), not to mention the wear and tear on the brakes and the drive train. Does anyone have any input on this problem? With as much detail Lexus put into the design of these vehicles I can't believe that this is normal.
  • geofeltgeofelt Member Posts: 2
    I recently bought a certified 1998 lexus ls400.
    After a couple of weeks, I heard the horn alarm honking at 10 pm. Going outside(on the middle of a rain storm) I found the lights were blinking,horn honking, all windows down, and the sunroof open. Theory was a one time lightning related event.
    A week or so later, I came out in the morning and found all the windows down and the sunroof open. Local lexus dealer checked it out and found no codes or problems.
    A week later, In the morning, I found the same thing, is windows down,sunroof open. Took it to the dealer, he ordered aa replacement control module. As an interim he gave me a loaner car, a lexus rx300. Part needed to be shipped from japan, it's been a week.
    Today, I go out, and find the windows down, and the sunroof open on the rx300!!
    What can be going on? There is no way I could hold down the open button on the key for the ten seconds or so to open all the windows without knowing it. I suspect some kind of local radio transmission. What is the mechanism that the key uses to open all the doors and sunroof? Is there not some security unique to the key? Any other theories? HELP!!
  • stripedcatstripedcat Member Posts: 10
    Do you have a cell phone in the car ? This could be the case.

    In my previous car (not an Lexus), the alarm used to go off as well. Apparently, the cell phone and the alarm system share the same frequency.

    If you do have a cell phone in the car, turn it off or take it out. Calling the cell phone will not help, as apparently, when the cells make the contact with the phone, this phenom occurred. Good Luck !!
  • geofeltgeofelt Member Posts: 2
    An idea to pursue. I don't own a cell phone, but my neighbors might. Does anybody know what frequency might be used in the car? It would be an awful design because any thief who knew the frequency could cruise the streets, opening any car that responded. I always thought that all signals from the key to the car were unique to the key. When the alarm went off in the original occurence, I think it was a normal alert that the sunroof was open and it sensed the rain. The problem, I think, is the windows opening, and not the alarm system.
  • alcanalcan Member Posts: 2,550
    Another possibility, my neighbor A's garage door opener will activate neighbor B's remote starter.
  • q45manq45man Member Posts: 416
    To minimize cold start emissions [EPA requirement] the engine computer sets idle speed based on coolant temperature. This helps heat the catalytic convertor faster to normalize emissions.
    Generally it is not a good idea [to prolong engine/tranny life] to crank and drive away on a cold car the fluids need time to reach [or at least get close to] their correct operating temperature.
    The designers assummed owners would be familiar with this requirement and let the car idle 3-5-10 minutes [depending on temperature] before driving away when ambient was below 60F.
    Not doing so decreases the life of components.
  • lbalestrilbalestri Member Posts: 2
    I need tires for a 95 Ls 400. Can anyone suggest which brand is best.
  • fxashunfxashun Member Posts: 747
    Driving away as soon as the car is running smoothly to speed up warmup, decrease fuel consumption and emissions.
  • marktnguyenmarktnguyen Member Posts: 1
    Does anyone have directions on how to clean/repair/replace the buttons? They sometimes work, but they have to be pressed REALLY hard.

    Is there a way to remove and inspect the buttons without having to take apart the door? I can't seem to figure out how to start taking the door apart. What tools would be helpful?

    Thanks.
  • roddmod11roddmod11 Member Posts: 55
    Well here I am again, if you open the hood and look at the throttle body and you will see the TPS is is a black round unit with one cable coming out of it,if you have TRAC you will have two of them, the one on the right is the one to adjust, to fix the high idle problem take a marker and draw a line on the TPS to the throttle body this will mark the spot where it is adjusted now, then loosen up the two screws that hold it on just about one turn, then rotate the TPS and 1/4" from the mark ccw, tighten up the screws and give it a day to adjust, it took my idle from 1400 to 1600 down to 1100 and lower quicker. Good Luck
  • roddmod11roddmod11 Member Posts: 55
    I have seen many post about the Trunk wiring and the wires breaking, here how to do a little preventive maintence on your cars, find the wiring harness on the left side of the trunk hinge and pull the wires out of the plastic holders unwrap the tape around the wires and you will find you can pull the wires to the left now take a cuter and cut away the covering in that area so the wires don't get hung up in that area, there you are done wires are nice and free no more sharp bends no more worrys about that problem.
  • fxashunfxashun Member Posts: 747
    with no blown bulbs?
  • deacon1984deacon1984 Member Posts: 10
    I don't know about the 1990 LS400, but on my 1991 the plastic piece around the door handle and the memory buttons comes out without tampering with the rest of the door. The piece is held in place by plastice tabs and snaps in and out. The biggest tab is actually in the center of the piece.
  • pj2323pj2323 Member Posts: 43
    do you have any idea about post #404?
  • darren15darren15 Member Posts: 1
    Hello everyone,

    I have a 1991 LS 400 that im very happy with However, over the past few weeks my "low oil pressure" light has been coming on.
    This indicator only seems to come on when I get on the freeway or travel at high speeds and will only stay on for about 6 to 15 seconds. The car runs perfect from what I can tell; and this "oil pressure light" concerns me. I've checked the oil levels and there fine, I've also replaced the "oil pressure sending unit". Nothing fixed the problem. Does anyone have any ideas as to what might cause this light to ignite? could this be a serious problem or something minimal? I spoke with a friend and he informed me "it's probably an electrical problem since replacing the "oil pressure sending unit", didn't correct the problem it in the first place."
    Any ideas or suggestions would be appreciated. darrenlake@yahoo.com.

    thanks in advance,

    -Darren
  • roddmod11roddmod11 Member Posts: 55
    Hi the only way to know for sure is to have a pressure gauge installed to see what the pressure is, there is no other way to be sure, oil pressure is determined by the condition of the rod and crank bearings. Good Luck
  • nunyanunya Member Posts: 4
    My 96 LS400 has some brake noises and I don't know if they are a concern or not.
    When I back up the car, stop, go forward and then stop, there is often a clunk sound at the right front wheel. It isn't loud but is noticeable. Is this the brake pads reseating or something?
    Also when I start driving there is some brake squealing the first couple of times I apply the brakes. It doesn't continue.
    I just had the 30k service done at a Lexus dealer and they didn't say anything about either item and they test drove it. The 30k service includes a brake inspection. I forgot to say anything to them. Now I'm wondering if everything is OK.
    Whatcha think?
  • pj2323pj2323 Member Posts: 43
    has anyone had any problems with the speedometer not working on cool mornings on 1992 LS. after the car is driven 10-15 miles, it starts working.
  • tomj5tomj5 Member Posts: 209
    I had a simular problem on a Mitsy I own. Very diffcult problem to find. Car computers are very dumb and only check a limited amount of sensors.
    I found a shop that really knew their stuff on the modern fuel injected cars. The problem turned out to be the Throttle Position Sensor located on the throttle body. The computer only checks the presence of the sensor not what it is doing. The sensor was putting out a weak signal to the computer. There are slotted screw adjustments on the sensor, but do not mess with it! Let the Pros adjust it! If you move it you can mess up the computer zero settings and wind up with a galloping idle. (Yup, I did it.) I would get on the web and find a local fuel injector specialist. Forget the dealer. Most dealers won't spend the money to hire good mechanics. In my experience.
    Also, Summer fuel (smog additive) can cause idle problems. Good Luck..
  • alcanalcan Member Posts: 2,550
    Engine control computers constantly monitor voltage levels on every input sensor, opening and closing internal circuits as sensor signal voltage levels change. Some, such as camshaft and crankshaft position sensors, are digital (on or off) Others such as throttle position, manifold absolute pressure, mass air flow, air intake temp, coolant temp, etc, are analog (continuously variable). The ECM uses the TPS signal voltage level to determine throttle position. Some are adjustable to provide the correct voltage signal relative to throttle position. TPS signal voltage of about .45 V indicates closed throttle, just under 5 V indicates wide open throttle. It's used for air/fuel ratio calculation, torque converter clutch apply/release, trans shift points, etc, etc. ECM's aren't "dumb" or "smart". They're signal processors.
  • q45manq45man Member Posts: 416
    The 0.4 volt to 4.4 volt range is divided into 5 or 10 segements: 0% [closed]....10.20.30.40 etc 100% WOT. Many have an additional closed throttle and WOT "kickdown" switches. Much of the tranny shift control is related to exact correct percentage of throttle opening {LOAD} vs RPM/SPEED.
    Having a TPS off by even 0.1 volt will raise havoc especially at idle since the ecu is geting 2 conflicting signals.
  • q45manq45man Member Posts: 416
    Common for the LS displays to get intermitent since the car is 9-10 years old, don't worry the flickering problem will go away when they fail completely.
    Have you flushed yor PS system lately they clog [small internal screen] and fail causing leaks which take out alternator and PS pump.
  • fxashunfxashun Member Posts: 747
    do you have to replace the whole speedo? Tat would play havoc in a low mileage Lexus's value.
  • pj2323pj2323 Member Posts: 43
    there is no flickering. the only thing that doesn't work is the speedo needle. when the car is started, it doesn't work. after the car is driven 15-20 minutes, the speedo needle starts working correctly for the rest of the day. the next morning it does the same thing. i thought it may be a sensor. i have recently replaced ps pump, ac hoses, evap core, temp control display, interior electric door lock controls, antenna and motor, timing belt, water pump, and several other things. i bought this for a second car, but it has been expensive to operate.
  • sweetv12sweetv12 Member Posts: 58
    friend's battery went dead and tried to jumpstart...car would start but once jumper cables pulled, car dies...replaced battery and car starts fine...problem now is all electrical is dead...lights, radio, etc. do not work. anybody have an idea what to do and why this is happening? I am a DIY type so will need specific guidance..

    thanks in advance...
  • pscmjpscmj Member Posts: 7
    I tried moving the TPS CCW by the recommended 1/4". Unfortunately I could not move it but about 1/8" before I hit the "stops" for the screw slots. Hoping this would be enough, I tried it anyway. After three days, the cold idle speed is still the same, no change (about 1200-1400 rpm). About the only thing I have noticed is that the change from second to third gear happens much quicker. So, I am going back to the original position for the TPS. From what I gather in the postings thus far, the TPS could need replacing, and/or the coolant temperature sensor. Any thoughts on testing procedures or replacing these components. Also, since this is a Lexus, any idea how much they would cost if they do need replacing?

    Thanks to all those who have responded ... if nothing else, it is helping me understand things a little better.
  • q45manq45man Member Posts: 416
    The TPS voltage is critical in telling the transmission computer and engine how to behave indiscriminate adjustment [AWAY FROM CORRECT VALUE] to try to adjust idle speed is a NO NO despite the recommendations of shade tree mechanic.
    Now you have the problem of resetting it exactly with a VOM.
    The car sets the idle correctly for the coolant temperature assumming the intake track is clean [no build up of crud from PCV and EGR] which is usually the problem with high idle along with dirty injectors.
  • nunyanunya Member Posts: 4
    My 96 LS400 has some brake noises and I don't know if they are a concern or not.
    When I back up the car, stop, go forward and then stop, there is often a clunk sound at the front wheel. It isn't loud but is noticeable. Is this the brake pads reseating or something?
    Also when I start driving there is some brake squealing the first couple of times I apply the brakes. It doesn't continue.
    I just had the 30k service done at a Lexus dealer and they didn't say anything about either item and they test drove it. The 30k service includes a brake inspection. I forgot to say anything to them. Now I'm wondering if everything is OK.
    Whatcha think?
  • q45manq45man Member Posts: 416
    Duh! when you remove the jumper the car dies, NO alternator output becuase you let the PS leak on the alternator too long causing it to fail!

    New Speedometer will be programmed to old mileage by factory on modern all electronic units -- requires dealer certification to avoid Federal tampering charges.
    A real exert can take the new needles off a New Speedometer and replace without changing the unit but you must buy a new speedometer to get needles....saves an hour or two but I would want a whole new unit installed as there are otherthings to go wrong.

    All older 90,91,92,93,94,95 [12-7 years old] will require maintenance and repairs. Japanese parts are expensive. If you buy a used car which was poorly maintained you will have to replace lots of things. AC systems, alternator, water pumps, belts, timing belts, services are just normal wear items around 100k or earlier.

    Lexus has front tension rods and upper A arm bushings which wear and allow movements [noise under braking] these should be checked and replaced when worn.
  • q45manq45man Member Posts: 416
    The TPS voltage is critical in telling the transmission computer and engine how to behave indiscriminate adjustment [AWAY FROM CORRECT VALUE] to try to adjust idle speed is a NO NO despite the recommendations of shade tree mechanic.
    Now you have the problem of resetting it exactly with a VOM.
    The car sets the idle correctly for the coolant temperature assumming the intake track is clean [no build up of crud from PCV and EGR] which is usually the problem with high idle along with dirty injectors.
  • capostolcapostol Member Posts: 11
    I am a second hand owner of a 93 LS400 and had a question about the power antenna? My power antenna comes on when you turn the key to the accessory position - not when the radio is turned on. When does your antenna come on? I'm trying to figure out if this is an aftermarket antenna and there are times I need the antenna to be down and the car still on.

    Thanks.....
  • blkmgkblkmgk Member Posts: 54
    I own a 96 LS400, and I owned a 93 LS400 and both cars antenna went up when i turned on the RADIO.
  • blkmgkblkmgk Member Posts: 54
    What is the correct oil to use in a drain and fill job for a 96 ls 400. The dealer tells me they use TYPE -T. DEXRON.
    The owners manual say TYPE-T-II. The service dept guy I spoke with said he doesnt know about that.????
    the guy at autozone said its ok to use DEXRON III.(they did not have TYPE-T-II like my manual indicates)
    I read a post #385 and he says the dealer tells him to use IV-its ok.
    Can someone please clarify this for me-I am conFUSED!!!
    What is okay to use and what is not?
    My car has 98k and it is 30k over tranny oil change.
  • roddmod11roddmod11 Member Posts: 55
    Don't get all up in there with Q45 man, you marked the TPS so you can always go back to the original setting, the idea is that the switch for idle is a touchy adjustment, keep trying to set the TPS, when you have it right you will know, try the other direction just a tad at a time, don't let them worry you they like to make stuff complicated, I work on Linear Accelerators, they think this car stuff is complicated, this is nothing.I have got the service manuals, I was just trying to give you the easy way, anyone can rap off service manual stuff.
  • roddmod11roddmod11 Member Posts: 55
    The lastest and greatest is TYPE IV no matter what anyone says, get it at you LEXUS dealer if he does not know that TYPE IV is the right stuff get a new LEXUS dealer. Don't worry about the 30K over just have it done the 30K is just a opening of the drain plug and 2 liters out and 2 put back in, do this now and again in 1K, and every 30K you should be OK, or if you want the complete flush fine but only with TYPE IV.
  • blkmgkblkmgk Member Posts: 54
    Thanks a million! That is all I needed to know.
    any details I should follow when doing this?
  • q45manq45man Member Posts: 416
    My choice of the word critical should have given parameters: The tranny/engine ecu divides the TPS voltage into 10 steps: 0.4, 0.8, 1.2, etc to 4.4 volts...something like 0.61 volts might be rounded up to 0.8 volts or 0.59 might be rounded down to 0.4 volts! Every unit varies with temperature and production tolerance.
    Setting the warm idle voltage correctly is the key to normal operation.
    If you still have idle speed problems then you look elsewhere for the solution.
    Qualifications: BSEE, MSEE.
  • blkmgkblkmgk Member Posts: 54
    since this would be the first time I do a drain/fill, can anyone tell me exactly how to do this , since I have never done this. where do I find the drain(dont laugh) and do I need to drop pan?
  • crowbait1crowbait1 Member Posts: 15
    Q45man and roddman11: you guys are both treasures so stop the quibbling. Lots of people have great credentials and many more do great work. So shake hands and know that there are a bunch of LS400 owners who appreciate your expertise and actually enjoy the differences of approach you bring to the table.
  • q45manq45man Member Posts: 416
    There would be lots of people out of work. If owners did all they could [preventative maintenance][within the limits of their pocket books]. Understanding that for most a LUX car is the second most expensive item in their budget...not counting second homes, airplanes, big boats, RV, mistresses, etc.
    Ever wonder why you see so many AC, transmission, and radiator shops, all these people make a good living out of ignorance.
    Preventative maintenance is always less expensive than replacing a component and worse, replacement components may not be of the same quality or capacity as those used in the building of the vehicle since the average replacement warranty is only 12mo/12k.
    When you drive a car as well designed as a LS [or a Q45, MB etc.] you just can't do nothing and let the components fail from YOUR neglect.
    We have many customers [salesmen] who have over 250,000 miles on older LS but they understand the needs of such a car.
  • q45manq45man Member Posts: 416
    When a new model is design a certain extra number of parts are ordered and built to new specs. Internal factory QC may segregate the iffy ones for use LATER as repair parts since they only have to last a little while. When these are gone [due to malfunctions and repairs], the factory may order another round of replacements using further reduced specs to maximize the profits.
    Worse are aftermarket partial rebuilds or remmaned which may be horrible.....especially AC compressors, evaporators, condensers, alternators, PS pumps, and transmissions.
    If a dealer part lists for $600 and and after market part costs half to a third you are getting what you pay for, since the dealer markup is at worst 40%.....if you chose wisely you can get almost the new component life vs a year.
    Most independents must buy from dealer not at cost but a 15-20% markup so they can only make 20% on parts thus they push aftermarket where they can SAY they are saving you money [in the short run] but in reality they are just trying to make the same 40-50% margin on parts sales.
    Think long term!
  • pscmjpscmj Member Posts: 7
    Hey guys, thanks for the information. My aim was not to cause any friction, so my apologies ... but sometimes, differing views can be a good thing, especially for those of us who are new to these vehicles.

    With regard to my 1994 LS (I bought used back in April, 77K miles), I turned the TPS back to its original position. Everything is as it was before I turned it CCW to the screw stops. FYI, I am an electronics engineer, and manager of an industrial electronics repair department. So, I am not afraid to do something as long as I know I can get back to where I started. In this case, so far so good. I have volt meter. Where can I connect it to test the TPS voltage levels q45man suggested? Also, is there a nominal resistance range I can check for on the temperature sensor when the engine is cold? If so, what is it, and where can I take these measurements? I don't have the service manuals, so any information you can provide (sensor locations, measurements and test points) would be appreciated. While I'm on the subject, any thoughts on where we can get service manuals other than from a Lexus dealer. I asked, and they quoted me a price of $245. I said thanks, but no thanks (at least for now).
  • rd8ard8a Member Posts: 11
    I bought a 1996 manual for $55 at ebay auctions about a month ago. Give it a try.
  • roddmod11roddmod11 Member Posts: 55
    1.Loosen the two adjustment screws of the TPS.
    2.Insert a thickness gauge (0.040mm/.0157)between the throttle stop screw and lever, and connect an ohmmeter between terminals IDL and E2 (E2 is the top pin IDL is the one under it).
    3. Gradually turn the TPS clockwise until an ohmmeter resistance is gone, then secure the sensor with two screws. page FI-53

    Pretty complicated stuff.

    The temp sensor should have a ohm reading of 10 to 15k omhs at 32F and 3 to 4K at 68F. Code for temp sensor is 22.

    To check for codes (which I would do first)the basic check follows.
    1. Turn ignition on.
    2. Connect a jumper to terminals TE1 and E1 of the TDCL connector (there is one under the dash and one under the hood,the one under the dash is round and on the left side below the gas and trunk releases. On the bottom row of terminals the TE1 is the one on the far right and E1 is the third one over from the far right side on the bottom row.
    3.Read the diag code from the check engine light.

    Write down the flashes there might be more than one code, codes on first gens they are two digit, so flash flash, flash flash = 22 Good Luck
  • roddmod11roddmod11 Member Posts: 55
    The drain for the transmission is right in the pan under the trans, take a look, do not drop the pan unless you have done this before on a car, the dipstick is attached to the pan and should be pulled, if you do the drain of 2 Liters, which is what comes out from the drain after removing the plug, and refilling with 2 liters though the dipstick tube, after you put the drain back in, should be all that is needed, Note Lexus does not recommend changing the Trans Filter EVER!? or the Fuel filter!? EVER, Know Why, I do and will post at a later time as it is getting late.
  • mwiklemwikle Member Posts: 62
    might try http://www.books4cars.com/
  • blkmgkblkmgk Member Posts: 54
    Beautiful. Thanks. Where would i be with out you!?
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