Can chips be found and replaced by user?

No, it's not realistic. Don't you think that the witnesses at the crash will notice him switching the chip? I am sure the trail of blood in the engine will help the police find the new chip. Plus, the lack of dust and dirt on the chip and the marks where he had his fingers on the chip, too. Plus, the chips probably have a date/time stamp with the recordings. The police will find it a little odd that the last recording was two years before.

This is a stupid idea. Besides, if it is a bad crash, he will probably be too injured to make the switch (or at least his underwear will be).

Jeff

My exact thoughts also. Are the chips even accessible with ordinary tools - my understanding is they are hidden under layers of steel? Ray O tell us please. jl

It's part of the memory bank in the ECU. You can't pull the chip without removing the ECU, and then pulling the proper chip, and then your car won't function.

A year or two ago, there was a guy here with a Celica that ruined the engine. He was upset because Toyota wouldn't honor the warranty and replace the engine. Fact of the matter was, the ECU disclosed the engine was run up to about 9,500 or 10,000 RPM, well over the redline!

IIRC, the ECU records road speed through the speed sensor, engine RPM through the tach, air bag deployment and a few other parameters. So, yeah, with the proper tool, these parameters can be read from the ECU, and I believe it's done through the OBDII port.

The computer thing that hte OP is talking abojut is probably not the ECU thing, but rather, a different device, like the black box here:

Your friend probably has no idea what he is doing and is unlikely to fool any investigating agency. There are no user replaceable "chips" in a Toyota. The chips are part of the various electronic control modules (ECM) and are soldered in place. One would have to replace the powertrain management ECM and the supplemental restraint ECM at over $1,000 apiece, and the ECM's would have to have events recorded that at least came close to matching the crash evidence. An experienced investigator can look at a wreck and make a pretty good guess at the vehicles' speed at the time of impact. If your friend programmed his "chip" at 30 MPH and the accident occurred in a 50 MPH zone, and his "chips" did not record brake application but an examination of the braking system indicated that the brakes were applied. IOW, one would have to pre-program ECUs for every possible permutation of events, like road speed, transmission gear engaged, steering angle, brake application, angle of impact (you would need 360 degrees), and whether there is one or two front passengers. Recording events would also involve deploying air bags because an event recorder that did not indicate air bag deployment when they deployed would also raise questions. Trying that move would probably get someone prosecuted for evidence tampering.

Will Toyota read the ECU database when requested by the customer? e.g. before buying a used vehicle, when you suspect your ex wife who borrowed your car just redlined your engine at cold start? how long is the data stored in the database?

"Toyota" will not, but I imagine that a dealer would if you paid for the technician's time.

My guess is that the ECM stores about most recent 5 seconds, 30 at the most, of operating parameters.