Crazed Idiot Lights

2002 Sienna, 50K miles - one day, the brake and ABS light illuminate. Mechanic does complete brake job (bleed lines, adjust and clean), lights pop on two days later. Then they go off again. Then the engine light comes on. Then the tire pressure light glows. And they fade. And a few days later, the check engine, brake, ABS, and tire pressure light glow. Then stop glowing. Then the speedo dies. And then comes back to life five minutes later. And when the speedometer is not working, the cruise control does not work.

Took car to another shop, mechanic said all connections are connected as they should be. The problems are intermittent, with no discernible rhyme nor reason - wet weather, dry weather, full tank of gas, half-tank of gas, city streets, freeway, cold start, warm start, sometimes all lights burst on in the middle of driving.

Bad computer? Ideas?

There may be a ground connection that is not making good contact. The negative terminal on the battery is connected to the chassis, and the power returns through the chassis. If a ground connection is intermittent, the power may feed back through another path. There may be a chassis ground behind the dashboard that isn’t always making good contact. Your best bet may be a shop that specializes in elecrical repairs.

I agree. 100%. You need a specialist in vehicle electronics/electrical systems. Your local Toyota dealer is unlikely to have such a specialist.