JusB

General Hi folks, I be new here.
I have an RX350 2007 model that cranks but no start. The codes all point to 6 bad ignition coils, but I find this hard to believe. Also, there was a code for crankshaft sensor, but I replaced it, and that code is gone. Now I get a code for camshaft sensor, P0340, so I pulled the plenum or intake, and swapped the difficult one that's supposedly bad to a more easily accessible location. The code changed from 0340, to tell me bank 2 sensor A. While I had the intake off I pulled the spark plugs, to clean and check, and I found one had a bent electrode. No scars or obvious signs of impact, so I regapped it and moved it to a more easily accessible spot.
My question is how to determine if there is a problem with timing chain/belt before I shell out money for new sensors. If I know the chain/belt is ok, then I will proceed and likely replace all 4 sensors before I put the wipers back on.
Any help would be greatly appreciated.

JusB

Thanks anyway.
Can anyone here point me in the right direction for some guidance? Please?

Mesquite77

Sounds electrical, see here (and the links) for options:

https://www.clublexus.com/forums/rx-...agnostics.html

and it might be helpful to be more descriptive in your subject title, just saying...

JusB

Thanks for the tip, I'm new to this forum stuff.

JusB

Thanks. I didn't want to start out saying that I suspect the ECU, but that's my belief. Also, I don't hear the fuel pump. I removed the seat and used a jump wire and it does work. I've checked all fuses, and verified that the circuits are getting power. Can I unplug a coil, and with the key on probe the coil harness for power?

Again I thank you for your input. I will look for grounds when the rain stops. I do hope that the alternator isn't the culprit ( sending dirty power, or leaking A/C into the system). It's a serious pain to remove...again. It had to come off, along with the compressor to replace the crank sensor.

Margate330

​​​​Did you just buy the car like this or have you owned it a while?

When did the problems first start happening and please describe the details of how it ran, etc.

JusB

We bought it like this. Actually it belongs to my friend, but it's parked outside my door. It turns over but no start.
The codes I have listed, Initially the codes were all 6 coils and crank sensor.. I can't accept that 6 coils went bad at once, so I changed the crankshaft sensor,
I cleared the codes and gave it a try, this time it says all 6 coils and P0340. Had to take the top off to get to that camshaft sensor, so I decided to check the plugs.
One had a bent electrode, but no signs of impact, no scarring etc. but it made me wonder about the timing chain or belt. I moved the bad sensor to the easiest spot to get to and put it all back together, with the exception of the wipers, and the P0340 changed to p0390, so I have a bad camshaft sensor, but still no power to the coils or the fuel pump.
Before I shell out more money for the sensors I wanted to determine if the chain or belt may have broken. If so there's no point, and I'd be wasting money that I don't have.
I did pull the seat and ran a jumper wire to the fuel pump, and I do hear it come on.

Thasnks for the help.

Mesquite77

Car should start without an alternator, disconnect it if you think it is bad, and try to start. Fuel pump is quite, to hear it, open the gas cap and listen at it while someone turns on the ignition.

Yes, you can pull a coil and plug and probe it out of the cylinder, good start. Compression check to see if valves are ok, try on the easy front ones, although all plugs should be out normally, just to see if in time enough to give compression.

Finally, has it been sitting in the rain? I had a crank, but no start once 6 years ago, never happened again, but my daughter had parked it under a tree with a million leaves and an all night rainstorm, I think leaves in the plenum directed water into the engine bay harnesses, still don't know.

JusB

OK, will try that, but why would there be no power to the coils?

JusB

OK with the ignition ON, I probed the coil connector, and there is only 5 volts. Is that enough?

Margate330

​​​​​​I will check on my car tomorrow and let you know

I believe there is +12v common wire for all the coil packs. There is also a signal wire that goes back to the engine Ecm so it knows the coil fired, this wire should be low volts and pulse hi logic when the coils fire, if I remember correctly.

If you can get your hands on a logic probe, you can see the coil feedback pulses. Must be an led logic probe and not an incandescent bulb type tester. They are dirt cheap.

A scope is better like posted above but a logic probe can give basics.

JusB

I would be eternally grateful if you could let me know about the 12 volts.
If one of the coils is shorted, it may be that the ECU is halting power to coils AND fuel pump.
That would explain alot.

JusB

Can anyone here, or should I say will anyone here give me some advice?
I suspect that this is a bad ECU. Likely a coil shorted and fried it. This means I need ECU and 6 coils.
That's a heap of cash to waste, with no guarantee that it solves the issue.
So, I was wondering...since I don't have access to sophisticated test equipment, can I unplug all 6 coils, clear the codes, and see what codes pop
then? If there is 12 volts at this point I just replace all 6 and be done with it.

JusB

Is there an ignition relay on this car?

fortitude

Invest in the Lexus repair manual

https://techinfo.qa1.toyota.com/tech...a.com%3A443%2F

or
Dave Graham one
https://www.rockauto.com/en/catalog/...r+manual,10335

Its covers detailed diagnostics, wiring diagrams, torque specs, etc..

As for electric parts such as crank positions sensor, cam sensor, vvt solenoid sensor, etc, stick with OEM (from a reputable source). When the aftermarket one fails, you will end up buying the OEM. Now your out the cost of the aftermarket AND the OEM