JimKing

iTrader: (2)

I picked up a 150k mile 2002 IS a little while back for a daily driver. It was a very good price.... because it was throwing a bunch of codes. The EVAP, catalyst efficiency and O2 codes are not a problem, but the main thing was the throttle motor. When that stops working it's major PITA.

I replaced the motor with a NEW one. Yet in the past two months the it has stopped working twice, with the ECU reporting P1126 and/or P1128. Turning the engine OFF and restarting gets it working again... for weeks at a time. I've checked the wiring - it's OK. Only other thing mentioned in the factory trouble shooting manual is the ECU itself. I've opened the ECU box cover - and it seems to be running pretty hot. Too hot to touch for more than a moment.

Has anyone else run into this?
What about the ECU temperature? Could internal components be degrading such that the throttle motor current draw monitoring circuitry is fooled?
Has anyone every tried ventilating the ECU box better or adding an additional headsink to the ECU?

daddystop

Is the throttle you used an OEM one or is it "rebuilt"?

It would seem to me that there's no need to vent the ecu box. If it's getting too hot it's because something is causing it to get too hot. Also, the manufacturer accounted for the fact that the ecu is going to get hot and I believe there is a vent coming from the radiator fan shroud going right into that ecu box..... so it's already "cooled".

Your check engine codes indicate a problem with the throttle body. What does "check the wiring" mean to you? Have you tested the resistance of all wires that dictate the operation of the throttle?

JimKing

iTrader: (2)

Thanks,
The motor was new-in-box from Toyota. I ohmed out the 4 wires going to the ECU. All good. Only thing left is the ECU

daddystop

I wouldn't count on the ECU being bad. I've been messing w/ cars for a long time and haven't seen ECU's just fail. What I have seen though is people replace expensive ecu's and expect their problem to be fixed and it's not.... and they're out of the money for an ecu.

There are other things that will cause the DBW throttle to behave badly. I believe leaks in your intake and exhaust are two of those. All I'm saying is I'd rule as much out as possible before buying an ECU, that'd be like my absolute last resort since they typically do not fail unless someone has done something to them to cause a failure.

JimKing

iTrader: (2)

I'm just living with it for now. The engine/tranny is ticketed for swapping into my 1990 Cressida anyways. If the problem persists after that, I'll dig into it further.