I was accelerating to merge into traffic at maybe 30 mph and pressed on the pedal just a little bit to get the car up to speed. The engine and instrument cluster (lighting, needles, etc) cut off for a split second. It is almost as if someone turned the key off/on quickly. This hasn't happened before and I drove the car fairly hard with lots of accel/decel/stop/go for about 30 minutes the following day and there were no troubles.

Since the instrument cluster turned off I suspect some power or ground problem. Could an ecu issue cause the instrument cluster to turn off?

 

sounds like a bad ground somewhere, did you go over a bump?

 

There were no bumps at all. I've also run over some bumps and have not noticed anything like it. I haven't removed or installed any ground or power wires. The clamps arnd posts on the battery are clean and solid. Are there certain connections I should check out? I had an early 80s vw scirocco with ignition switch problems that would cause hard starting and interrmittent engine cut outs. Is the ignition switch ever know to cause trouble on the ls400? There are no related issues I can think of...

 

Interesting problem... have you checked the rear connections behind the dash?

Could also be faulty sash lights?

Id try another dash cluster if it persists.

 

my ls400 ran just fine without the dash cluster installed (drove the car for a week when I sent it out for repair), so I don't believe that would cause the engine to cut out.