RX300 Won't start At Times
 

My wife's 2000 Rx300 refused to start the other day. It cranked over but wouldn't start. I had it hauled home on a roll-back. I replaced the 5-year old battery and tried to get it started again, but no luck. I called the tow-company again to have it hauled to the dealer. When I told the driver that it cranks over but won't start he asked me for the key, got in and it cranked right over and ran. He said it had something to do with the anti-theft system. My wife called me tonight from work because it happened again. It cranks over but won't start. Does it really have something to do with the anti-theft system , the master key, or what? It's driving me crazy! Do I have to have it hauled to the dealer to be repaired? I sure could use some ideas. Thanks.

If it is cranking at a good speed, then problem has to be with the ignition (spark) and/or fuel-air.

The anti-theft kills the spark. You can try removing all other keys/magnets from your key ring (to avoid interference) or try starting with the spare key [master/valet both should work].

Actual spark plug problems usually manifest in rough idle and loss of power (typically one plug at a time goes bad).

Fuel problem occurs when injectors get clogged or when you are out of gas.

The air problem is typically due to some sensor causing the ecu to mess up the air ratio.

For diagnosis, I would recommend a visit to the dealer. It is lot better /cheaper to drive it to the dealer on its own power.

It seems like "cold" start problem. Has it ever given you problem when the engine is hot?

Salim

happens to me this summer, a friend of mine is a long time mechanic at toyota and he said its common issue with toyota/lexus that it wont start or the engines wont stay on, it has to do with idle control valve<ICV I think he kept saying it> so he did me a favor by take it apart and clean it down and reassemble, and I have no problem with it since. only charges me $40 for labor, its worth it compare to change out the ICV which cost about $200 I belive. so maybe this is something you should check. Typically if you trigger the anit-theft it wont even crank.

Most of the time when a RX is cranking good but wont start it's the Idle Air Control Valve (IACV). Next time it wont start, try working the gas pedal while cranking. If this gets it going it's the IACV.
If it's cranking good it's not the battery. Spark and anti theft are possibilities, but long shots.
To check key and anti theft system, notice that when you enter car security light is blinking about once every second. Insert key in ignition. Blinking should stop. At this point you know your car is recognizing your key and turning off the engine imobilizer.

I would clean the resistor sensor wire in the intake tube. I had this problem and 10 cents worth of alcohol and a qtip fixed it. I think it was called a mas air flow sensor.

Good advice:thumbup:
Salim

I once used one of my old keys that had a broken plastic end to it, thus the electronics in it were dead, when I used this key the engine would crank over,,,but no spark was present and the engine would not even pop, when I changed to a good key it started right up...(fooled me for quite a while !!)

So I had the 2000 RX300 hauled to the dealer on Saturday. Today the dealer rep calls and tells me I need a new master key. I say OK, I'll pick the car up this afternoon. Then he calls to tell me the car won't start and that they have to look deeper into the problem. Then he calls to tell me that the ECU is bad, gets mixed signals to/from key. New ECU costs about $1600.00 but that dealer will ONLY charge me $800.00. I guess it's because I'm such a swell guy! Has anyone ever experienced this problem? Car only has 69,000 miles. Isn't electronics great!

I thought for sure this would be another case of IACV needs cleaning but I guess not. Lexus dealer has the car and he should be the expert. I have never heard of another ECU failure of this type but I guess it is possible. It would be nice if you had the car to actually see if the ECU was reading the key (security light stops flashing) but at this point I would be inclined to go with the dealer. Anyone else??

Dealer must have found out that "kill ignition" is preventing the run condition. The thing in the path are "sending key", pickup around the ignition key, ecu and all the wires/connectors in between. At this time they are simply going through swap and check.

The pickup can be confused by other magnetic sources around the sending key. [that is what I suggested in my first response.]

Dealer has the best equipment and know how on this.

Was there any work done in an around the steering column?

Salim