I have a 1990 LS400. The check engine light and trac off light are both on. The owners manual says only on california models can I run a jumper wire to see whats wrong. Is this true, or does this work on all models??

 

Go to an Auto Zone, Pep Boys, Advance Auto, or whatever your local auto parts chain is. They will have something to pull the diagnostic codes for you. My guess is your oxygen sensors, common cause of this symptom. Post back and let us know what you find out.

Good Luck!

 

Not true.

Go to SC400 site and search on the subject. I posted the procedure on how to retrieved the code last year. You have to know the code before trouble shoot the problem. Post back the result and someone will help you on the code

Good Luck

 

Also make sure your gas cap is on tight. Had a loose cap cause mine to pop on in my LS a month or so ago.

 

I too have an 1990 LS and I diagnosed mine by just using a "jumper" wire (paper clip).

 

My Check Engine light is also on.......the TPS(throttle positioning sensor) failed......$250 to replace it.