acmc415

I have a GX 470 2006, purchased it with 70,000 miles now has 130,000. I replaced the belts, water pump bearings, plugs and so on at 120,000 miles.

Present Issue is.... Six months ago the original key with three buttons broke. The metal portion from the plastic housing. I then ordered an EBay key and had it cut, I installed the button system from the original key into the new and all was well until just recently. We notice the traction control lights had come on Sunday, this had happened once before and we just removed then reinstall gas cap, lights went out. However this time we tried the same with no results but car still running fine... Monday my wife drove to work, (no issues) left work and went to pick up our daughter, vehicle would not start. It would turn over and act like it was catching then stop. I went to her with the second key in hand,(no buttons on this one but a factory Lexus key that came with the vehicle. I tried her key and it would turn over but not start, I tried the second key I brought with me and it started as usual. We had also notice the battery in the key my wife normally used was going dead, (having issues locking/unlocking doors with key. I have replaced the CR1616 in it. Tuesday wife goes to work no issues leaves work no issues goes to pick up our daughter and same thing, it would turn over but not start with either of the two keys. I come over with the key in the plastic card and vehicle starts and we come home. Today we went to doctor with all three keys on hand, left office and vehicle would not start. Tried all keys and finally it started with the key in the plastic card. We are now home, I have disconnected negative battery wire and left for five minutes. I cannot get the vehicle to start now, it turns over but doesn't start. (((( Yes, the red car shaped light with key shape in it does go out when I insert any of the keys))))
What in the world?????????

acmc415

OK more info....
I have been dealing with this more. As I stated above, the red security light does go out with all keys and it was acting like it was trying to catch or start.
Well I was cranking the engine over and playing with the gas pedal. I noticed the engine seemed to almost start more. I was able to get it started with two different keys within just a few minutes messing with the throttle pedal.
What now????
Anything???

lesz

Perhaps, someone with more knowledge of how the engine immobilizer operates will chime in, but I believe that, if the vehicle doesn't recognize the key that you are using as belonging to that vehicle, the engine immobilizer is activated. When that happens, I think that fuel flow is cut off to the engine, which sounds like what you are experiencing. According to the manual, when the engine is immobilized because the vehicle doesn't recognize the key, you need to wait a bit before trying again. I also seem to recall having read (a long time ago), that, if you make repeated attempts to use a key that the vehicle doesn't recognize, the engine immobilizer will eventually remain active for some extended period of tim e. Thus, it sounds like one or more of your keys is not being recognized as a key belonging to the vehicle. In the manual, it talks about how a key can be damaged resulting in it no longer being recognized by the vehicle. If one of your keys is a replacement key, there could also be a problem with its programming.

My guess is that, if you made a call and talked with a service adviser at a Lexus dealer, he/she would likely be able to immediately know what is going on.

acmc415

At this point it seems the keys are being recognized. The red light does go out and when trying the flat key and not placing the card close to the ignition switch there is a completely different sound but while cranking if I place the card close the sound changes to (not getting enough fuel)
At this point I am leaning more towards a fuel delivery issue.
I was able to get it started twice with two different keys within just a few minutes by adjusting how much I was pushing down on the gas peddle.

Crazy???? Yes

acmc415

Maybe throttle position issue????????

chiph9

I think it isn't an immobilizer issue, since the light is going out.

Seems to happen when you restart when the motor is warm. So possibly vapor lock (fuel pump, vacuum leak, etc). Or something else (of course!)

Chip H.

acmc415

So what we figured out at the dealership ... The sorry lowdown no good guy who replaced the timing belt, water pump and other stuff (ME) didn't secure one of the cam sensor wires and the belt wore through that wire or partially at least. They replace it and all was well...:

chiph9

Doh!

Glad you were able to get it resolved, anyway!

Chip H.