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LS 400/LS 430 Electrical Questions & Problems

lsbrasillsbrasil 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 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 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 Posts: 10,421
  • CN,

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


  • patpat 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 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 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
  • 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?
  • 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 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.
  • 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
  • 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?
  • 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
  • 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.
  • 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 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 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 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 Posts: 1
  • j7wildj7wild 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 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 Posts: 14
    yes it's in the trunk, you will need to pull the trunk carpeting off... did you see my link above?
  • darinhdarinh 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.
  • 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...
  • 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.
  • 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!
  • 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 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 Posts: 10,706
    I have been buying my replacement batteries at Costco of late and simply rely on their cross-reference catalog.
  • j7wildj7wild 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
This discussion has been closed.