Top 10 1991 Lexus LS 400 Questions & Answers

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Where is the computer box in the Lexus LS400

Where is the computer box in the Lexus LS400 located?

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There are 11 electronic control units(ECU) located in the dash area. They are as follows.
Engine + trans. ecu. behind right side of the dash.
Abs + traction ecu. beside the engine ecu.
electric mirror ecu. behind upper right side of dash.
SRS ecu. behind dash at console.
Shift lock ecu. in center console near shifter.
Power seat ecu. under drivers seat.
progressive power steering ecu. behind left dash left of column.
Steering column tilt + telescopic ecu. behind left dash above column.
Anti-theft ecu. behind far left of dash.
Cruise control ecu. just below the anti-theft ecu.
My guess is you are looking for the engine ECU but you may be
looking for 1 of these in the future. Hope this helps.

Posted on Sep 30, 2010

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how to repair code13 - RPM signal no.2 Lexus Ls400

how to repair code13 - RPM signal no.2 1991 Lexus Ls400

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HOW TO FIX CODE 13 1995 LEXUS SC400

Posted on Nov 30, 2010

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radio locked 1991 lexus ls400

i have a 1991 Lexus ls 400.My radio is locked.Does anyone know how to get it unlocked.Tried all combos of my code now permanently locked.Please help

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do you know how to reset radio code lexus ls 400 /1991

Posted on Oct 30, 2009

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car alarm went off while unlocking the door, now

i unlocked to passenger side door with the set of keys without remote and alarm went off. i got my key with the remote to shut alarm off. now car wont start at all. All the electrical stuff works it just wont start.. pls help!

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you need to reset alarm/immobiliser.lock car with remote, hold button down for 30 secs,then press/hold down unlock button,should reset.another way is with key in ignition/turned on, press alarm button down and hold for 30 secs.this resets immobiliser.toyota
systems vary..depending on market.

Posted on Mar 30, 2010

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Car shuts off immediately after starting.

1990 Lexus LS400. The car will start and turn over...but dies literally a second after it starts. I have no clue what it is. I think it may be the fuel pump? Also, there is a light on in the dashboard..that I have no idea what it means. It looks like a tiny little trash can or birdcage maybe..is hard to describe. What is that?(when i bought the car..the owner's manual was missing)

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I think you are on the right track with the fuel. Find your fuel to the engine and disconnect it. Put it in a container and crank the engine over. How much fuel comes out? It should be a good steady flow if not you either have an obstruction in the line or a faulty pump. Hope this helps.

Posted on Sep 21, 2009

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1993 Lexus Ls400 loss of power at 2500-3000rpm

1993 Lexus Ls400 loss of power a 2500-3000rpm when you accelerate
hard on the gas pedel, hower if you press down on the gas pedal slowly the power will increase all the way up to 6000rps with no power lost. The power is only lost when you press on the gas pedal fast all the way to the floor of if you try to accelerate full power from a dead stop.

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Check your MAF and MAP sensor. The first 80% of your throttle signal from the TPS works with the O2 sensor to try to keep the air fuel ratio to 14.7 to 1 with the ECM controlling the fuel injector spray time and timing the ignition. After the 80% to WOT the ECM puts the O2 sensor in to an open loop and takes the Reading form the MAF and MAP sensor to run the engine richer so there will not be any Detonation to the engine and burning holes in the valves for running too lean. That is why it always feel like you get a little more when you ease off on the gas peddle from WOT. Recap check the TPS, MAF,and MAP sensor and wires to those sensors, if you can get the car scanned that would be great and you may find out which sensor may have gone bad, the other thing to is the fuel pressure regulator may be going bad and at WOT the pressure may be to high causing it to run to rich causing the loss of power. Good luck and hope this helps. 

Posted on Jul 04, 2009

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Replace/fix starter on 1991 Lexus LS400

How difficult is it to replace/fix starter on 1991 Lexus LS400?

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Not too bad. Not much room, just enough to drop the starter. It is probably easier to go up through exhaust if you can get your exhaust shield off the manifold .

Posted on Aug 07, 2009

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ls400 indicator lights coming on

my 1990 ls400 low engine oil level, discharge warning, low engine coolant warning lights - all come on at same time like yours.

Have you found a solution. My alternator stops charging when this happens.

Thank you
psieng@bellsouth.net
225-819-6589

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you need a new alternator

Posted on Mar 27, 2009

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how to change the fuel pump on 1991 lexus ls400

how to change the fuel pump on 1991 lexus ls400

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remove rear seat then remove cover in the trunk, you will see a cover remove thatcover and remove 8 bolts holding fuelpump in tank,also dissconnect connector to fuelpump with bolts removed the pump pulls right out.hope this helps.

Posted on Mar 01, 2010

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1993 lexus LS 400 speedometer works sometimes

The sensor was changed but that did not help. Sometimes the speedometer works, and sometimes it does not. It will work for a few hours and then stop working. i have a 1991 lexus ls 400 and the speedometer has stop working. when u are stop the needle is all the way down past 0 but when u get to fourth gear 2,000 rpms the needle rises not all the way too 0 but close? please help

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the plastic gear on speed sensor is broken , replace , this is on transm. rear case

Posted on Jun 18, 2009

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