Dave209

I've been having an increasing problem with my 07 RX350. This happens with both keys (my wife's and mine). You put the key in the ignition, turn it and it will crank and crank but won't start. So, if you pull the key out, put it back in then it starts. It's been happening about every third time we try to start the vehicle. Any ideas on what it could be? Starter sounds fine, and since it happens with both keys I'm pretty sure it's not the FOB. I would appreciate any assistance.

Audiqv8

Is the anti-theft light on while cranking when it doesn't start?

Dave209

I haven't noticed it but when my wife gets home with it I'll check and let you know.

Dave209

Well, it didn't start when I tried it. (No security light). I tried starting it again without removing the key and it still just cranked. Once I took the key out and tried again it started right up. Getting more frustrated as it's happening so often now. (It did it once several months ago and then did it two or three times a couple weeks ago.)

Mesquite77

Had that happen to mine once after a night of heavy rain. Was because of so many leaves in the plenum, that water got into the engine bay during rain, and caused shorts on wiring, near as I can tell. By repeatedly trying to start it it, by leaving the ignition on, the current eventually dried things out enough to allow start. I then later later soaked that car repeatedly with water, and can never duplicate the "crank but no start" problem again. After 2 years since then, never had the problem repeat, but I keep the leaves out of the plenum.

Dave209

I'll check it in the morning. We have had the trees dropping a lot of "helicopters" and such over the past couple of weeks. I keep the engine bay clean along with the filter box etc. but haven't checked it in about 3 weeks. It's worth a look for sure. Thanks for the suggestion!

DennisMik

Another possibility could be that the contacts in the ignition switch are wearing out. The ignition switch screws on the back side of the ignition lock where you put the key in. I don't know how to test this other than put another ignition switch on. The switch costs between $20 & $120, depending on where you buy it. The Lexus part # is 84450-12200.

Here are some photos. The first one is from a thread on how to replace the ignition lock itself.( http://www.clublexus.com/forums/rx-2...placement.html ) It shows the ignition switch. The second one is the ignition switch itself.

Dave209

Very helpful Dennis! Thanks for posting the information and the photos. I'll add this to the "work list" of things to look into. It may be worth it to at least pull it and clean the contacts first and make sure everything is tight and has a good connection too.

DennisMik

I don't know if you can clean the contacts on the ignition switch. It seems to be a sealed unit. If you do try to work with the switch, maybe you can remove the ignition switch without taking the lock assembly out of the dash

Dave209

Hopefully I won't have to remove the lock assembly. I'll take a look at it tomorrow and see what I can accomplish. Thanks again for the input!

Nad1370

If its cranking, its not going to be a contact issue.

Do you have anything "electronic" in your key chain?
I seem to remember the old Mobil speed pass would create transmitting problems upon starting.
Or maybe a remote starter in the vehicle?

Insert just that one key in the slot,
Wait like 5 sec and see if starts.
Take note when the security light goes off.
It should go off as soon as you insert the key without even turning it.

Dave209

Interesting. I spent the morning cleaning the throttle body and Mass Air Flow Sensor and checking various connections under the hood. It failed to start first time on 3 out of 5 times throughout the rest of the day. I don't have anything with my car key. Not even a key ring. (I hate having a ton of junk hanging from my ignition). I'll try inserting the key and waiting 5 or so seconds before turning the key to see of that alone may make a difference. Thanks for the suggestions.

DennisMik

There are multiple contacts in the ignition switch, six I think it is. While the contact for the starter solenoid is OK, one of the others may be flakey. But I still don't know if the ignition switch is the problem.

Dave209

Yesterday evening I went out and checked things over again. Security light goes out the second I put the key in the ignition. If I wait at least 5 seconds then turn the key it started every single time. I tried it 10 times. Even drove it a short distance and tried some more. That is the first time in days it has started right off every time without fail. More confused than ever. I don't know if it's the waiting 5 seconds that's doing it or if something in the contacts just happened to be lined up correctly right now. I did order a new ignition switch on eBay. I want it here just in case and I'm wondering if it may be worth it to go ahead and replace it anyway. Just don't want to have to pull the entire key cylinder to do it.

Nad1370

^^^
Thanks for confirming the checks.

Seems like you have a transmitter delay issue here.
To start the vehicle ( immobilizer side )
Key transmitter (in the key) ---> Transponder Key amplifier (Key coil, 7 pin connector around the ign cylinder ) ---> Transponder Key ECU ---> Engine ECU to start the engine.
Any of these could be your issue or a communication line in between those.
Once the security light goes OFF, it means the Transponder ECU see's the registered Key on the ign cyl.
Therefore in my opinion, the engine ECU gets a communication delay to start the engine. (my theory of course)

If you have access to an able scanner, it can check if there are codes stored in the Transponder KEY ECU.
Or have an able shop try to:
Re-register the ECU communication ID between the transponder key ECU assembly and ECM.

If it was me, i'd be happy waiting 5 secs to start it.