LS 400/LS 430 Electrical Questions & Problems

lsbrasillsbrasil Member Posts: 1
edited October 2014 in Lexus
I have a 91 LS 400....running great, but I have a small issue I need answers to. When I apply the brakes the reverse light indicator on the dash lights up. Also, the car automatically downshifts as soon as the brakes are applied. I think it is electrical posibly to do with anti-lock brakes. Brake lights and reverse lights operate perfectly but, just wanted to see if anyone knows how to fix this problem


  • wwestwwest Member Posts: 10,706
    Sounds as if some previous owner has modified the shifter electrical circuits to cause an automatic downshift upon braking. Probably not a hard thing to do/undo and not altogether unreasonable.
  • cneumancneuman Member Posts: 55
    With this new set up, I'm not sure where to post this. But here goes. I have a 2002 LS that sometimes will not start. So far it's always been in the morning, after sitting all night in the garage. Sometimes after it sits for a half an hour or so after the first try, it will start up on it's on. It has started right away with a jump on two occasions. It's not the battery. That was the first idea I was given, so I bought a new battery. Does anyone have any idea what the cause might be?

    Thanks for any help given.

  • patpat Member Posts: 10,421
  • brichwallbrichwall Member Posts: 2

    What was the outcome to this issue. I am having the same problem. Please let me know as soon as possible.


  • patpat Member Posts: 10,421
    Hi - welcome! Check the Lexus LS 400/LS 430 - Startup Questions. If you don't see anything helpful, post your problem there. Explain what's happening in your post. Good luck.
  • seanc1seanc1 Member Posts: 1
    Recently tried to charge a cell phone via the cigarette lighter in my 1994 Lexus LS400. Result - blown fuse - lost all heating/ventilation. Replacing the fuse does not solve the problem - tried it.
    Any ideas??
  • dsteinerdsteiner Member Posts: 2
    1991 400 LS--6 weeks ago the traction light came on and the dash lights would flicker. Then the car jerked slighly when driving. then there was an odor like a electical fire. Then the car would not stop running when the key was turned off. We have replaced he starter, fuel injectors ( the cylinders on one bank were ful of gas) and he brain box. The porblem still exits where the dash lites flick off and the car wont shut off. hte lex dealer cant find the issue and my mechnic commited suicide trying to find this issue. SAVE ME! -signed $1500 later and no peace
  • rouge69rouge69 Member Posts: 1
    I'm trying to locate all the fuse boxes on a 95 Lexus LS. The dealership told me that the third one is on the passenger side of the vehicle but i cant find it.Can someone please help me in locating the third?
  • movinonoutmovinonout Member Posts: 1
    I have a 91 LS 400....running great, but I have a small issue I need answers to. When I apply the brakes the reverse light indicator on the dash lights up. Also, the car automatically downshifts as soon as the brakes are applied. I think it is electrical posibly to do with anti-lock brakes. Brake lights and reverse lights operate perfectly but, just wanted to see if anyone knows how to fix this problem

    Look for a wire bundle on the drivers side trunk hinge that flexes and breaks. this cause your reverse indicator to light up when the brake is applied and also feels like the transmission is disconecting or downshifting. Fix that wire, and your car will not jerk anymore when touching the brake.

  • rhoulerhoule Member Posts: 1
    Thanks for the wire bundle recommendation. I have a similar proble with my warning light that a bulb is burned out when there is none. Now when I apply the brakes the reverse light goes own and the transmission downshifts and the panel light goes completely off or flickers. Something is shorting out badly and hopefully it is only in the trunk.
  • bluesindbluesind Member Posts: 1
    I have developed a problem with my 1992 LS 400. The battery seems to have been in a bad state, slow to start, sometimes needing two or three tries to turn over (this happened over several months). Toward the end, all the warning lights on the dash came on - radiator, battery, oil - the whole shebang. The battery was so low while going down the road that the radio only worked while the heater was off!

    I replaced the battery and the car starts fine now - but all the warning lights (as mentioned) stay on. What could this be - and what needs replacing?

    Dallas TX
  • ckennedyckennedy Member Posts: 82
    My passenger side view mirror on my 2001 LS 430 does not retract fully when I shut the car off but will extend out completely when I start the car. The driver side works fine. The mirror stuck another vehicle while driving a ways back according to my wife. Any ideas as to what is involved? Is this a dealer or regular mechanic issue?
  • brem15brem15 Member Posts: 1
    I left my lights on the other day and when I tried to start my car, the battery was dead. What is strange is that the first time I tried to start my car, nothing electronic worked. The steering wheel didn't come out and nothing else worked. However, when I went out later the lights came on when i opened the door and the steering wheel came out like usual, but the battery was still pretty dead.
    I hooked up a charger and let the car charge for a while and the car started right up, but nothing electric worked. The steering didn't come out, the dashboard didn't light up, the windshield wipers didn't move. I checked a few of the fuses and changed the interior dome fuse and now the interior lights work, but the dashboard doesn't work and I checked to make sure that the dashboard fuse is ok and it is. What could be the problem. I obviously need electronics. Also, I had a garage check the batter and they said that it was ok, not great, but fine.

    Also, once the car was started I tried to put it in gear and the gear shifter was locked. I pressed the Shift Override button or something, but nothing helped.

    Thank you for your help.

    Springfield, IL
  • golfguy1golfguy1 Member Posts: 4
    I have a 97 Lexus LS 400 with a blown fuse. I have removed the screw on the outside of this fuse but can not determine how to get to the inside screw. I removed the screw from the top of this line of fuses but can not remove this "line of fuses" to get to the inside screw.

    I don't want to break anything. I would appreciate your help.
  • payrodpayrod Member Posts: 1
    Hello, i have a 1991 Lexus LS400. The panel lights are out. The lights for the heater/AC, radio and clock are out. I don't know if i can change the lights/bulb are does the whole panel needs to be changed. Please let me know, they do function but the lights on them just don't work....Thanks!!
  • ahaithahaith Member Posts: 1
    A friens of mine has a 92 LS400... the start runs great, but the oil alternator, battery,and coolant lights come on when I start and stay on constantly! Other than those lights, the car seems to perform flawlessly. Is this an easy fix? Should I buy it?
  • vguthrievguthrie Member Posts: 2
    Just today I experienced the reverse light indicator and downshifting issue when the brakes were applied. I read the response to check the wire bundle and found a white wire completely cut. In the event I have to replace this bundle is there an official name for it? Also...I've been trying to figure out a surge issue I've been having on acceleration especially on a grade. Could this all be related to this cut wire in the trunk????
  • j7wildj7wild Member Posts: 14
    Hi JL,

    did you ever find out the cause of your problem?

    I am experiencing the same thing on my 1992 L S400 and I have a brand new battery, the oil is full, the radiator is full and the engine is not overheating, etc

    It seems to come on when I'm going slow (under 30mph) or stopped but when I speed up, it goes off.

    It drives fine too.
  • damien15damien15 Member Posts: 1
  • j7wildj7wild Member Posts: 14
    like I did but it no longer works, it should be in the trunk after you remove the CD Changer:

    anyway I found the cause of my problem; the Alternator was going out; it's all fixed now.
  • wwestwwest Member Posts: 10,706
    There is for certain an amp under the front passenger seat but I seem to remember another one, bass speaker driver(??), in the trunk.
  • j7wildj7wild Member Posts: 14
    yes it's in the trunk, you will need to pull the trunk carpeting off... did you see my link above?
  • darinhdarinh Member Posts: 1
    Hi Damien15,

    Mine was located in the trunk, drivers side, just left of the gas tank. Of course I had already found the site " carstereohelp" and pulled my CD changer out before I realized that mine wasn't under there. Still a good site and will go there for info. again.
  • rbb50rbb50 Member Posts: 1
    I Have a 1992 Lexus ls 400 with @ 270,000 Kilometers on it.. The engine occasionally shuts down if I use anything electric on it ... For example, If I touch the brake peddle, use the turn signal, open / close the window, the car will stall out and usually restart immediately. It doesn't happen al the time, just occasionally but I cannot find any common factor. Also, whether it is related or not, the gear shift lever will jam and the release button has to be hit hard to release it.. If the car shuts down, the lever must be jiggled to get the car to restart. Other than the electrics problems its a great little car and runs fine.. any suggestions ... thanks...
  • j7wildj7wild Member Posts: 14
    if you go back to my previous post #19 on page 2 , my problem was caused by the alternator starting to short out so I had it and the battery replaced.

    Everything ran fine for about a month and then I started having a problem SIMILAR to yours and to #10 on page 2.

    Same thing: car will jerk like it's downshifting when I apply the brakes and the Reverse indicator on the dash will come on and the whole instrument panel will fade out.

    Also if I turn the headlights on and I'm going faster than 30mph, the speedometer will drop to 30mph and it won't go any faster and the engine rev meter will go up to 4 or 5 and it sounds like you are driving in neutral.

    The first time this happened I was driving home from a friend's house at 3 am , 16 miles away, and I pretty much limped home at 25 mph max.

    One more thing is the O/D indicator will flash saying it's off and then it disappear.

    I took it back for repair and they replaced a cable in the taillight that was shorting out and it caused a brake light to go out.

    After that, it's working fine now and I hope it stays that way.
  • vguthrievguthrie Member Posts: 2
    I own a 1993 LS400. I had a similar problem but not as crazy, found that there is a cluster of wires in the trunk hinge on the drivers side. Constant wear from opening and closing the trunk one of the wires had been cut. Everytime I applied the brakes the reverse light on the panel would lite up and the car would "clunk" as if it was trying to go into reverse. Don't know if this will help but there are alot of wires in that cluster something could be cut and causing your car to go haywire!
  • j7wildj7wild Member Posts: 14
    yeah I'm gonna check it out because there light out warning light on my instrument panel keep lighting up and I had my wife stand behind the car while I use the turn signals, the hazard, step on the brake, turn the lights on and she can't see a single light that's out

    thanks vguthrie
  • acco20acco20 Member Posts: 211
    I will soon need a new battery for my 2001 LS430. I have checked the battery itself and I have checked all the manuals and can not find any numbers or discriptions that would lead me to buy the right battery. I mean what size, cranking power etc. I am concerned when I do not know exactly what I am looking for. Can anyone help??? Thank you. wwest...are you out there by any chance...
  • wwestwwest Member Posts: 10,706
    I have been buying my replacement batteries at Costco of late and simply rely on their cross-reference catalog.
  • j7wildj7wild Member Posts: 14
    for my 1992 LS 400 was a 430 cranking amp battery and that's because the guy at Auto Zone told me I needed something that big for such big car
  • wwestwwest Member Posts: 10,706
    The biggest "challenge" for your car battery is in cranking the engine. These days most starter motors are reduction geared and therefore require less cranking amps than in days gone by. Additionally with all the electronics in control, especially EFI, engines simply start a LOT quicker.

    I would wager that a small garden tractor battery would supply enough AMPS to start an LSes V8 but accordingly would not have a very long life.
  • j7wildj7wild Member Posts: 14
    Wwest, so the guy at Auto Zone conned me then?

  • wwestwwest Member Posts: 10,706
    No, just good salesmanship...

    Except for lightening your wallet slightly more than necessary he did you no harm.

    Manufacturers of late have become a bit more conscious of weight vs MPG issues so while the higher capacity battery will undoubtedly weight more than the OEM it will also likely last longer.
  • wwestwwest Member Posts: 10,706
    The CD player in my brother's 91 LS400 will not change discs nor open the CD door but will play the CD currently in position. I traced the problem down to a pico fuse in the "head" unit. Does anyone know of a shop that specializes in Lexus radio repair...??
  • j7wildj7wild Member Posts: 14
    that's the Toshiba 6 disc changer in the trunk?

    same I have on my 1992 LS 400?

    same happen to mine, wouldn't open or change disc and I even try the reset on the remote control on the dash

    took it to Lexus, they couldn't fix it

    took it to a car stereo place, they told me don't bother

    so it's still in the trunk, just doesn't work anymore
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    I don't think it pays to fix these old things anymore. I'd just replace it.
  • j7wildj7wild Member Posts: 14
    you are correct; I feel the same way.

    but I wouldn't even spent the money on a new car stereo for a 16 year old Lexus with 200,000 miles on it

    my nephew is turning 16 next year and is going to start to drive - I am thinking how selling the car to him - his first car, a Lexus!!

    my first car was a 1976 beat up old dodge van with no ac and am stereo
  • wwestwwest Member Posts: 10,706
    1991-92 LS400 radio often blows one of the fusible links inside the radio head. Specifically the one that passes the B+ from the dome fuse through the radio and then out to the CD. C21 pin 4 from the dome fuse into the radio and then through the fusible link to C9 pin 6 out to the CD. There is a second fusible link for the acc B+ out to the CD but that one doesn't blow.

    Anyone have experience with this...??

    Radio aways operates even with the fusible link blown and CD works perfectly until the fusible link blows, days or weeks apart.
  • wwestwwest Member Posts: 10,706
    I am in the process of wiring in an external fuse in parallel with the internal pico fuse. Shall I copy you on instructions...??
  • wwestwwest Member Posts: 10,706
    B+ (battery 12 VDC) pin at the CD player connector was shorted to ground. Provided a B+ power bypass around the connector and all is well.
  • wwestwwest Member Posts: 10,706
    CEL on my brother's 91 LS was due to failure of the EGR valve vacuum modulator.

    Over $100 at Lexus of Memphis and needed to order.

    In stock (92 Camry) at Hutton Toyota for ~$70.
  • wwestwwest Member Posts: 10,706
    I'm just finishing up installing replacement aftermarket seat heaters for our '95 LS400. In the process I discovered why the OEM ones failed...POOR DESIGN.

    The OEM seat heaters are designed poorly in that the elements can too easily come in contact with the metal frame of the seat. That's why both front seat heaters had failed.

    It turns out that there is a TSB that covers this flaw for the '95-'00 LS400...5 years to discover and correct an obvious design flaw. The TSB reads that it only applies under specific customer complaints and only while the car is still under the factory warranty.

    So if you own a '95 to '00 LS400 and your seat heater(s) have failed now you know why, TOO LATE...
  • mike425mike425 Member Posts: 6
    I have a 2004 LS 430 and the keyless entry stopped working. I can't lock or unlock the car or the trunk. I have had it to the dealer ( they had it for 2 months ) to recalibrate the remotes to the car, with no success. The car has 56,000 miles on it and the dealer doesn't know what's wrong with it, the Lexus factory technican has checked it out and even been in contact, I am told, with the engineers that built it. They can't get an error code on any of the diagnostic equipment, pin pointing the problem. They think it is something in the wiring harness or a computer that is fastened to the inside of the firewall that requires the whole dashboard to be removed to get to it and that may not be the problem. The dealer has suggested an aftermarket remote to lock and unlock the car, or just live with it ( why did I buy a Lexus, if I have to do that ).
    I have been in contact with Lexus, but unforntunately they were not much help. The dealer suggested that I don't fix the car, because it will cost thousands of dollars to repair. I went back to Lexus and they said take it back to the dealer and the dealer will basically rebuild the car, at my expense. That's a bit scary folks.
    Does anyone have any suggestions or experience with the keyless entry, because I don't really want to give my dealer a blank check to fix it. ( I'm not sure they know how for starters )

    Thank You
  • wwestwwest Member Posts: 10,706
    Metallic window tint film...??
  • mike425mike425 Member Posts: 6
    No, only Lexus original tinting. The keyless entry was working fine, then just stopped.

    Thanks for the suggestion though
  • mike425mike425 Member Posts: 6
    Ladies and Gentlemen

    The keyless entry problem in my 2004 LS 430 with 56,000 miles on it, has been solved by Burdick Lexus in Syracuse,N.Y. These people investigated the problem and found two major components at fault, and they only had my car for a week. The first component was the Theft computer assy ($892) and the second was the Reciever door control unit in the trunk ($754), along with labor ($1,100) for a grand total of $2,746 to repair my LS430. The car is working like it should now and is enjoyable to drive again. When I first reported this problem to the Lexus Corporation, asking for some help in paying for some of this, because Dorschel Lexus in Rochester, N.Y. had no clue what was wrong it and didn't even want to try to fix it, and that's after they had my car for two months, Dorschel did offer some lame suggestions that I just live with it, or they can install an aftermarket remote to lock and unlock the doors on my $65,000 Lexus, for only $200. Lexus Corp thanked me for bringing this problem to their attention and informed me that they have sent this issue to the Lexus Headquarters in California, so that they can make a better product. How do you make a better product without the solution to the problem. Well now, thanks to me for paying for their research and development on this problem, they now have the answer. Lexus Corporation dropped the ball on this issue as far as I am concerned. It's too bad that I couldn't sell them the solution to their problem.
    On a very bright note though, for people in Upstate New York. Burdick is an outstanding dealership and they are huge in automobiles not just Lexus. I personally would like to test drive one of their BMW's and they also have Hummer along with too many more manufacturers to mention.
    I thought that anyone that has seen the keyless entry problem that I posted might be curious about the solution to the problem. Well here it is, so if your car has the same problem that mine did, it will cost you a smooth $2,800 to fix and don't count on Lexus Corporation for anything. I should state that my car is out of warranty as the Lexus Representative pointed out to me several times and they did not have to do anything toward helping with the cost of this rare component failure. I'm fine with that, I don't have to purchase another $65,000 Lexus either and neither does anyone else in this country.

    Have a Great Day
    Mike McNeil
  • bebe311bebe311 Member Posts: 1
    I have read postings on various websites that are similar to my problem, but not quite like mines. My interior power will not work at all! Nothing on the inside works (no heat, radio, dash, seats, etc.) nor will my head and tail lights work. I was told I had an electrical problem (which as not been diagnosed by an electrical technician) The vehicle drives fine, but I can not use any electrical devices for the car. I was told the problem is draining the alternator, which I just had one replaced. I did notice that if I turn on the hazard lights, I can see it blinking on the dash and it works outside of the vehicle as well. I tried to turn on the headlights, but they did not work, but I could see where I tried to put the lights on high beams.

    If anyone has experienced this problem, please advise!!

    Thank U
  • flatlanderflatlander Member Posts: 25
    This mirror is not adjusting from the dash controls although it will fold in or out. Is this problem common and/or fixable w/o buying a new replacement mirror?
  • wwestwwest Member Posts: 10,706
    edited June 2010
    Blown fuse or failed relay.

    Most likely the lighting system "integration" relay assembly/module mounted in the dash panel approximately above the driver's left knee.

    Check to see if the "flash to pass" headlight function works and if so the integration relay has failed.
  • lexus401lexus401 Member Posts: 2
    i have 91 ls400 when i drive it after it gets warm i hear a whinding noise sounds like power steering but its not. after driving 15-20 miles noise gets louder then dosent want to shift in 2nd or 3rd gear rpms will rev when accelerating but speedomonitor gets stuck at 20 mph????my lexus has 128,000 miles on it so i dont think its the transmission.issue # 2 ,when i step on brakes reverse light comes on. heater and a/c and clock lights dont light up. i checked fuses their still good. cant lock or unlock door with key....Please help!!!!!Thank You.
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