Hello,

I have a 2004 LS430 and the front left and right corner sensors go off by themselves when in drive but they work find in reverse. I tested them several times in reverse getting close to the house.

I measured the resistance of the sensors, they are both 10K. The sensor connector has only 2 pins so I don't think the sensor would know if the car is in drive or reverse, right? this is leading me to believe the problem would be in the wiring harness or ECU, does that sound reasonable?

I had the dealer look at it (for $179) (in Plano TX) they told me they think the sensors are bad but they did not replace them with known good ones for troubleshooting purpose. Hmmm. They won't let me talk to the tech. They want $1300 to replace both ($650 for 2 sensors and $650 for labor). Wow.

-jason

 

The front outside sensors are enabled when reversing because if you turn when reversing the front of the car swings and could hit something whilst you are looking over your shoulder.
This is normal behaviour and is mentioned in the Owners Manual.
The sensors are fine, it's the Computer that controls them that is misbehaving.

The easiest way to test the sensors/computer is to have someone approach each sensor in turn whilst in Reverse/Drive with your foot on the brake and see what happens.

 

I checked them this morning: When in reverse and the steering wheel cranked the front corner sensors warn me when I'm getting close to something. Good! When I put the car in drive the front corner sensors go all wonky when I'm far away from anything. All other sensors are working fine.

I doubt it's the sensors but I will replace them (with aftermarket) anyway since they are easy to get to, then look into the ECU/harness. Thanks.