JAB

1999 RX300, 228K, original owner. Strange problem. In the main fuse box, located on the drivers side of the engine compartment, there are several what I believe to be relays, marked Fan 1, ABS Motor, Fan 2, ABS Sol(enoid?), Fan 3, and A/F Heater. Yesterday I heard a 'chatter' coming from that area. Touching any of them causes me to suspect that one or more of them are chattering, as if they are cyling on and off fairly rapidly, but I can't isolate it to a particular one. It only happens with the engine off and the key completely out of the ignition; inserting the key slightly into the keyway stops the chatter. Yesterday this was simply a curiosity; today the car won't idle - must keep foot on the gas otherwise it stalls. Suggestions? Other than the failure to idle everything appears to be working OK, although two weeks ago the car ran out of gas although there was still an estimated 3 gallons in the tank.

Thoughts? TIA.

salimshah

Have the battery checked and charged if needed.

If the idle problem persists after voltage/battery checks out, IAC would be be culprit.

Salim

JAB

Cleaned the IACV and car runs and idles fine; thanks Salim! The batterty & charging system appear to be fine but the relay (most likely the 'A/F heater') still chatters. Any other thoughts?

JAB

Service advisor at the local Lexus dealer thinks (based on my description) that it is the ignition switch interlock. I suspect he is right. Anyone familiar with the anatomy of that device that can point me to the likely cure?

salimshah

Search on park reverse neutral switch + rx300

How is the gear shift display in the instrument cluster? Flickering or solid On?

Try wiggling the shift lever and see if the chatter goes off.

Does the chatter go away once you move the shifter to N? Be on flat surface and apply parking brake and you can shut off the engine.

The switch has an adjustment range but the contacts can be worm over time.

Salim

JAB

Sorry; I guess I wasn't clear. The chattering stops as soon as I insert the key, even just barely, into the ignitioni switch. So when the key is in, or the car is running, there is no chatter.