dbatease

I have a 1998 LS400. 221xxx miles. when put in park, on a hard stop, or even rolling from 2nd gear to 3rd gear, my check engine light and vsc light comes on. I am able to limp the car home by pressing the accelerator all the way down. When switching from park to drive or drive to reverse the car jerks into gear, then when back in park it idles up to 2000rpm. I instantly take the negative terminal off and reset the ecu for about 10 min and it automatically goes back to normal. This is been happening too many times (randomly can go from a day to a couple of weeks in between) and I never have a scan tool to catch it.

Has anyone else had this problem? What was the fix?

Yamae

It's one of typical symptoms of the limp home mode. You need to read the code first using an OBDII code reader. You probably will get P112X. Major parts shops have a code reader.

The resetting can be done removing the battery terminal. This simply means that sensors that use variable resistor such as the APPS（Accelerator Pedal Position Sensor） or the TPS（Throttle Position Sensor） is not stable.

Bylan

I would suggest you buy an OBD2 reader, they're like $20 these days. I have used these for years with my 1998 LS400, same as yours. Heres one that bluetooth pairs to your phone, and you can use an app like Torque lite on your phone to read OBD2 codes. This tool is a necessity for any basic troubleshooting:

https://www.google.com/search?q=elm3...hrome&ie=UTF-8

Lets make this simple. The gas pedal in our LS's is both mechanical and electronic. When you press down on the gas pedal, a steel cable that goes up to the engine throttle body is connected to an electronic sensor. This sensor does all of the moving of the actual throttle, instead of the cable, except the last few percent of gas pedal travel. This is a safety measure, since any of the sensors or motors could have a problem for a split second and will shut down (cant risk going full throttle). Get an OBD2 reader and report what your CEL codes are.

400fanboy

According to the internet, there are a lot of fake 327 sensors floating around out there with... limited functionality.

https://www.cnx-software.com/2022/08...ooth-adapters/

I personally bought this one:


Worked instantly out of the box with zero setup. FYI it's Android only, and "the problem" with cheap OBD sensors is really within the app rather than the sensor itself. The apps can really be hit or miss.