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All other parts are SOLD OUT and won't return, including the LS400 and SC400 turbo kit, rebuild kits, supercharger and performace torque converter. We're not an auto parts supplier and I can't respond to inquries for random Lexus and Toyota auto parts.

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Lexus Won’t Start But Has Power: How To Diagnose Starter Problems

Here are some possible diagnoses why your engine won’t start but has power.

Battery and Associated Cables

It is possible the battery is weak and causes the engine not to turn.

However, if you turn on all the lights and blast all the fans and still having trouble turning the engine, then it’s most likely not the battery.  Charge the battery and try again.

If charging the battery doesn’t help, its most likely not a battery or cable problem.  If the battery is weak, the starter will still engage but very weak or slow.  If the battery is really bad, you might hear the click, click, click, click, click sound.

Anti-Deterrent ECU

This is also a possibility, especially someone else drive your car.

This is very common if you lend your car to someone.  The symptom of this condition is “No noise or sound at all” when ignition key is turned.  If this is faulty, the symptom will be the complete ignition kill.  Therefore, you will not heard and clicking sound or engine turning at all.

If this is the problem, you can easily reset the Anti-Deterrent by using your key.  Stand out side of the car and close all doors.  Insert the key into the driver side door and turn the key to clockwise and counterclockwise for three four cycles.

Basically, you lock, unlock for 4 times and this procedure will reset the anti-deterrent ECU.  If this happen to you, it’s quite scary at first, but the solution is very simple.

Faulty Starter Relay

The easiest way to find out if the starter relay is bad is to open up the engine bay fuse box. You can use a flat screwdriver and take out the cover.

Have a friend try to start the car for you.  If you hear a click sound right at the starter relay (Green Color Square Type Relay) then the relay is good.

Second thing you can do is to borrow a starter relay from a friend.  If the working relay installed and the engine still not turning, then its not faulty relay.

Neutral Start

Believe it or not, the transmission shifter plays a role in starting your car too.  As your car ages, the transmission shifter linkage doesn’t give good contact to the starting system and your engine will not turn or click at all.

Here some signs of this problem.

  1. No P (park) or N (Neutral) indicator light while key on.  Even with P & N indicator lights come on but that still doesn’t it has good contact.
  2. When you turn on the key, you should not hear anything at all.  No turning or clicking at all.

To test this out, the best way is to push forward on the shifter until you see P while trying to start the car.  Or you can turn the key into on position and hold it there while pushing on the transmission shifter.

Remember this is a very common problem with older cars.

Bypass Starter Circuit

There are many reasons why the engine won’t turn.  It is possible the circuitry might be faulty.

However, you can test your starter without taking it out.  You can bypass the circuitry and use a positive (+) into the fuse box.  Here are the procedures:

  1. Open up the fuse box with a flat screwdriver.  The fuse box is located near the battery.
    2. Use a 10 mm socket and loose the fuse/relay module.
    3. From there you need to use the same 10 mm socket and loose the plug.
    3. Once the plug is out, look for a large black wire right under the Green Relay (Starter Relay) See starter diagram below.
    4. Supply the black wire with a power source.  Please be careful do not touch this hot wire to anywhere else.
Use a flat screw driver and loosen the bolts.
This is a typical picture of a LS400. SC400 is very similar too.


This is how it looks like when the cover is removed. Use a 10 mm socket and loosen those two 10 mm bolts.
The green relay is the starter relay.
Loosen the bolts and the whole module comes out.
Turn the module upsidedown and use the same 10 mm socket to unbolt the plug.
Once the unplug, you will see the starter relay wire as marked by the red arrow.
This is how you bypass the electronic circuitry.

When you supply power to the black (a large black wire right under the green relay) wire, you are pretty much bypassing ECU, relay and connectors.  If your starter is good, it should turn.  Then the problem might be somewhere before the wire or the starter.

If it doesn’t turn, then the starter is almost 100% faulty.You might hear a click sound but doesn’t turn.  This means the starter is engaging into the flexplate, but not turning.  You might hear only one click sound and that is it.

If bypassing didn’t cause the starter to turn, then it’s time to spend the money and time to replace the starter.I believe this is the easiest way to find out if the starter is bad or not without taking the starter out.

Faulty starter is rare, but due to the aging  process, its very common problem for the first generation 1UZFE cars.  This article is intended to rule out starter problem.  It’s much easier to change other parts associated with starter, than changing the starter itself.

The opposite side of the bypass plug is the back wire as marked in the picture.

Do you have any questions? If so, please head over to the forums to get a quick answer or share your experience!

Cash App (user: $lextremeparts).
This is a freelance site with no support by huge companies.  I have been doing most of the R&D and technical write-ups by myself with my personal money and literally thousands of hours of my time.  I have taken extra steps to demonstrate in details how things are done.  Currently I am one of the few people doing Lexus V8 research and performance enhancement.  This effort comes from my personal love for this wonderful engine.  Most of the modifications are from trial and error. There's no cookbook for 1UZFE mods and its unknown territory for much of supercharger performance.  The parts, labor, web development and site hosting are 100% paid from my personal hobby money.  If you feel my efforts help you in any form, please do not hesitate to donate any amount of money to support this site. You have no idea how much I and the entire Lexus and Toyota community appreciate it!

28 thoughts on “Lexus Won’t Start But Has Power: How To Diagnose Starter Problems”

  1. Checked the battery relay fuse both okay alternator should be good has power dash board lights up windows work ac comes on head come on but start won’t turn over turn the key nothing no sound no clicking nothing

    • I have Lexus GX460 2012 and it has starting issue from last 2 months. At first I thought it’s a starter but after some time the battery goes dead after 2 to 3 attempts to get the car started. Then I realized that may be battery is draining. I take the car to Lexus dealership they check charging system, starter, battery and all is good but daily I have to jump start the car and Lexus dealership have no solution to this problem. I am totally helpless. Do you anything about this issue.

  2. Hi I have a Lexus ES300 1996. So this is the forth no start issue. I’ve had my car for 3 months but it has over 398,000 miles. Each time this had happened all my mechanics say it has to do something with my circuit control relay (aka the fuel pump relay which is not really called fuel pump relay which is located under my glove compartment). Can someone tell me why this keeps happening and how I could further resolve this issue to never have this problem again?
    PS. Everything else seems to be fine but because I can’t get to mechanic right now the only thing I’ve ruled out that it’s not is my starter relay and my battery.

    • Hi Reg. I would highly recommend that you check our forums for an answer to your question. If you can’t find it, please post a new thread there.

    • The lexus is an exstremely finicky battery system. It has two cables that hook to positive side of battery with the lead positive on the top terminal. I first tested a failing system that was identical on a mitsubishi montero sport. Thought it was dirty cable so i cleaned and reattached. The next day the owner of the vehicle, called me and said her car did not have enough power to turn it over. I did a field test and while i was monitoring the multimeter, i was thrown by the different readings i was getting at various positions in where the small cables attached to the main. From the alternator it was testing 14.5 while running, but when i tested at either small cable it wass not even reading 12 volts. I new by the various readings that cables were oxidized in various places of contact and would not let the proper current through to charge the vehicle let alone add additional current to the battery. Well what noticed today is my lexus 600 has the exact same setup as the mitsubishi montero sport and i remembered what a pain in the ass it was to fix the mitsubishi properly. Went back four time. What was happening is the way they have the two additional cables attached seemed to be attached with a cheap pot metal that oxidizes and fails to keep the car starting and charging properly. I cleaned up the original and then cleaned and buff brushed the two cables coming in from the side. After cleaning and buffing what seemed like a perfectly clean two additional battery cables on the side and reattaching them i put my multimeter and tested down the side of the cables i had cleaned and had hit pay dirt cause it was charging on meter at 14.5 everywhere i tested as it should. The moral to the story is test in various places while running and be sure charge is reaching its destination, never assume that just because your getting 14.5 coming out of the alternator that it is reaching its intended destination. Saved her from the purchase of a new battery, starter and alternator.

  3. I have a 2004 Lexus gx470 that has starting issues. I have replaced the ignition sensor and that didn’t help. Had the battery checked out and is good. Your Ecu reset seem to work instantly by turning the key in the door 3 to 4 times and after it started 4 times consecutively it decided not to start again. When it does not want to start with the key in the on position I hear a slight humming noise coming from where the starter is located. Not sure if it the ecu or the starter going out ?

    • Hey Neil,

      I’m researching this – I also have a 2004 Lexus gx470 with a starter problem. Diagnosing it now. It seems completely random when it chooses to start (and turn right over like a champ!) or click once and do nothing. I brought to the mechanic, they said I need to replace the starter.

      However! I spoke to the previous owner, they had experienced this a few years back, but in a brand new starter, and it didn’t fix the problem. They believe, but can’t quite remember for sure, that it turned out the be the relay. I’m going to replace mine and see if that helps. I haven’t diagnosed the ECU yet.

      Let’s stay in touch. I’ll let you know if I figure it out, and please do the same!

  4. I have a 1998 Lexus es300. I just got from my boss but the problem is that someone tried to jump the car and put the terminals on wrong which I was told blow out the ECU. I then replace the ECU with a new one and tried start the car and the car won’t start. So far I changed plugs,wires,gas filter and pump, ECU, fuses etc. Can you please help me to diagnose this car. Thanks I’m about to change the starter relay Now because starting system fuse located under the dash isn’t coming on when tested. Thanks

  5. I have a 2010 lexus gx460 & my ignition refused to start it would make a 1 click noise so the mechanic said it was electrical & that he fixed the issues for $80 then the next day my car wouldnt start again i told him it was my starter then he replaced that for $200 that wasn’t the issue now he’s saying its the starter relay im fed up its time to go to lexus

  6. When it is cold sometimes when I try to start my 2012 Lexus IS 350 the brake wont depress and the start button won’t turn green and turn over. If I put my FOB against the ignition light it starts. Any suggestions. I brought it to a Toyota dealer and they couldn’t find anything wrong and of course it started every time but the car was warm then.

  7. Lexus IS350 is a reliable road companion, but its a machine with hundreds of interconnected parts, and like any other machine it sometimes fail to deliver normal operation. 

  8. I have a 2010 Lexus RC350 with 100k+ miles on. When I drive it for long distance then stop, the car won’t start right away until the engine is cool. Already checked starter, battery, relay everything is fine according to mechanic. Anyone has any ideas?

  9. I have a 2007 Lexus IS250 rear wheel drive II pushed the start button and all it does is it clicks the radio light flashes but the – doesn’t light up at all the AC little window doesn’t do anything at all it just everything clicks flashes and turns off and car won’t start start I tested the starter starter’s fine I jumped the relay so I know the starter’s fine the battery is fine all the fuse that seems to be fine all the relays seem to be fine but something is causing it to not want to start Like I said it just when you push the start button everything clicks and does nothing I have no – lights at all the gauges they don’t do nothing at all

  10. I think my rx400h has the “neutral start” issue. When I shift gears all lights (r,d,n,b) show except when I’m at park (no p light). I tried pushing the shifter forward while starting but nothing seems to get the p light to show. Any advice?

  11. I have a 2007 RX350, all instrument lights are on but won’t start, tried a new starter, didn’t work, there is a humming noise from both sides of the engine compartment, tried resetting the anti theft by locking and unlocking the door, tried a fully charged battery, nothing seems to work, any ideas?

  12. I have a 2012 Lexus SE350. A few months back the negative battery terminal came loose and i couldn’t start the engine. I found a procedure online that involved opening and closing the driver’s door several times and I got the car running. This has happened again. I fixed the cable connection, but I can’t find the restart procedure online. Can you give me the procedure.

  13. I have a 2009 250 Lexus that will not start, broke down on the side of the road had it pulled home, tried jumping it off still no luck?? What could it be?

  14. I have a Lexus 300 and am having starting issue. I was driving on a high way when the car automatically went off without a any sign. I called my electrician and he came and checked everything and said that everything is ok. I called mechanic, he said is a timing belt which he checked and said that nothing is wrong with the timing belt and I became more confused
    Please help out.

  15. We have 1992 LS400 we have lost power to the fuel pump mod, Car turns over but no fuel getting through. Thought it may be the fuel pump but now find we have no power to the yellow pump module .. Any ideas folks or do we just sell the car off for the motor..?


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