Hi,

I've been running a 2001 JDM Hiace Super Custom (2RZ-E engine, A45DL transmission) 2WD (RZH101G) for about a month. It has 100k miles. The transmission fluid dipstick shows the the right level but clear light brown, not red. No idea if/when the transmission fluid was changed. I'll be getting it changed in a week. The A45DL is a 3+O/D - no diagnostics or much in the way of electrics. It's in a 2001 van but I think they were generally in older vehicles.

It was driving fine, but after the first long drive, and after sitting in stop-start traffic for 30 minutes, it misbehaved when we got going again. Twice it dropped out of O/D back into 3rd when we were at about 60mph. It only did this for a few seconds before engaging O/D again. We were at out destination at that point, and when we went back home a few hours later, it was fine.

Since then, it's done this a few mores times. Usually when in the 50-60 mph range. Usually when not under any acceleration or great load. Just out of the blue. I think it's happened briefly when decelerating from 50mph. When it happens the RPMs jump about 1500, so it's not the lock up. The O/D off light does not come on when this happens, so I don't think it's an issue with the switch - but happy to be corrected.

Looking at the wiring diagram I have, I believe the petrol RHD vans have an O/D relay to control the O/D solenoid, rather than all the other models which have an ECU. But I've yet had the dash out to confirm that.

I'm hoping it's the relay, wiring or O/D solenoid but was hoping of some guidance. I'm in the UK where automatic transmissions are uncommon - so specialist shops are few and far between. And as it's a JDM import, not many places know much about it. So any ideas and suggestions are very welcome. Would pulling the cable from the solenoid help diagnose - if it stays in O/D? Could the solenoid still be the issue if the cable is off and it still happens (physical issue)? Or does it sound like expensive wear to the internals?

Thanks

 

how did you sort out this issue?

 

Yes, I did. Of all things, it was the ECU temp sensor?!?

For some reason, when it was up to temp and running a bit hot - say sitting in traffic - and then cooled slightly as the speed went up and the airflow into the radiator increased - then the temp sensor would send a signal that it was -20 deg C.
So the ECU thought the engine was cold and disabled overdrive (which it does to keep the revs up and warm up the engine and transmission faster). It started off doing this very infrequently - but then more often. To the degree that it was difficult to start the engine when it had been parked warm, but allowed to cool down for 15 minutes. The sensor was saying cold, so the ECU would flood the engine and it wouldn't start. That's what made me identify the issue.

A new £20 sensor fixed it. If you're getting the same issue, if you unplug the sensor, then the ECU defaults to think the temp is 80 deg C and overdrive should work.