Taking foot off the break pedal disables the vehicle.

[alflash]

Checking of Isolation Resistance between the stator to Chasis use Megaohmmeter






https://alflash.com.ua/2019/to_rav4ev/isolat_resist.png

 

[asavage]

From the Tesla service link I posted above:



Implies using the 500v test voltage for the stator ("all other components").

 

[alflash]

Note. IMO. RAV4EV Cabin Heater not use PTC Heater elements


Unlike what is shown in

 

[tjlee]

Before I forget . . . see the blue oval below? You have coolant corrosion on that wire harness. This is common, and is probably the reason behind the error codes you saw in TPD: the inverter control electronics can't work right. This is why so many LDUs get driven until they won't move, because just rust on the motor side won't keep it from driving, and the increasing noise from rusty parts rubbing or failing bearings won't get most people to look into it, but when the inverter gets wet . . .

View attachment 237



I'm not understanding: there are NO HV contactors in the LDU -- when we speak of "HV contactors", we are referring to the ones inside the battery case, bolted to the bottom of the vehicle.

You are testing the three big stator windings to stator ground. alflash has a short vid of this, but I can't locate it right now. It's easy to do, if your LDU is apart as yours is, and if you have the tool to measure insulation resistance. My repair doesn't require splitting the gearbox (I have NO coolant in the stator wiring "tunnel" nor in the inverter side cover) so measuring mine was more difficult, and I had to install plastic spacers between the stator leads and the inverter leads that they bolt to (under the orange HV cover and T45 screws).

As noted above, a multimeter or std ohmmeter will give a reading, but a megohmmeter actually applies 500v to the windings and is a much more reliable way to measure insulation resistance than a ohmmeter. But you use the tools you have, and testing with an ohmmeter is better than not testing at all.

I paid $382 for my Fluke 1507 via eBay a couple of years ago, but it's a $7-800 tool new. I figured I'd have enough use for it to own one, and this project (coolant leak on my LDU) was the 2nd time I'd had a real use for it. Previously, I'd been using one from work, but I've retired.

Thanks for heads up on coolant corrosion on the inverter. I'll check it out. I do have megohmmeter bought from amazon. Not an expensive one but I think it works. I did test the insulation reisistance on the stator leads and currently getting about 3 mohms after cleaning with water and isoprophyl alcohol. Before the wash I got 9-10 mohms. I used the house garden hose to wash it down and dried using compressed air and isoprophyl afterwards. Used a torch heat to dry more and afterwards left it out in the sun to dry further. Currently resistance test is not getting any better. I am getting continuity on all three leads of the stator(1-2, 1-3,2-3). Is this normal?

 

[asavage]

I don't know how to answer that . . . we don't have a lot of data from the field. Put another way, the information exists, but the people who have it don't share it.

---

I cleaned mine tonight, but my glycol intrusion was minor, with staining of the steel stator bars confined mostly to the outer 1/2 of the stator's length, and I just tilted the LDU to one side and cleaned it with a spudger, Simple green, and a ScotchBrite sponge, followed by a plain-water wipedown. I have no coolant in the "tunnel" nor the inverter side, so I've elected to not split the gearcase. In my case, everything visible cleaned up easily, but I stopped driving it as soon as the first sign of trouble appeared (one HV contactor opening incident and dash warning, "Check EV System"); I didn't wait until it was dead, as many people do.

I have "before" insulation resistance readings (4.7Mhom), and tomorrow I'll take "after"; I've got a fan/heater setup blowing on the wet stator's internals overnight.

Bottom line is that the HV system needs to stay above 1.8Mohms, so if your stator is at 3Mohms, you should be able to continue without further bother.

 

[alflash]

... I am getting continuity on all three leads of the stator(1-2, 1-3,2-3). Is this normal?

It is impossible to measure the actual active resistance of the stator windings using a conventional DVOM tester.
The stator current of RAV4EV (delta windings connection) can exceed 500A, so the resistance of the windings is small (to avoid unnecessary losses) and must be measured with a milliohmmeter.
This result of your this measurement is OK.

 

[tjlee]

It is impossible to measure the actual active resistance of the stator windings using a conventional DVOM tester.
The stator current of RAV4EV (delta windings connection) can exceed 500A, so the resistance of the windings is small (to avoid unnecessary losses) and must be measured with a milliohmmeter.
This result of your this measurement is OK.

aflash have you put everything back together yet. I got everything back together and it ran with no problem until started getting high battery temperature warning. Don't have the exact message but after awhile it puts in a craw mode do to high battery temperature. Just wondering this was do to coolant delete mod.

 

[hokiematt]

aflash have you put everything back together yet. I got everything back together and it ran with no problem until started getting high battery temperature warning. Don't have the exact message but after awhile it puts in a craw mode do to high battery temperature. Just wondering this was do to coolant delete mod.

See this thread: https://www.myrav4ev.com/threads/al...internal-temperature-imbalance-detected.2640/

In short, the motor coolant loop still has air in it. The instrument cluster incorrectly indicates battery temperature instead of motor temperature as the issue.

You need either vacuum fill the system, or use the TPD software to run the air purge routine which takes about 30 minutes.

 

[tjlee]

See this thread: https://www.myrav4ev.com/threads/al...internal-temperature-imbalance-detected.2640/

In short, the motor coolant loop still has air in it. The instrument cluster incorrectly indicates battery temperature instead of motor temperature as the issue.

You need either vacuum fill the system, or use the TPD software to run the air purge routine which takes about 30 minutes.

After complete install I did run the air purge system using tpd however air in the line prevented purge to properly purge. Even though the system saids complete I believe purge didn't purge properly. I've ran the purge once more and disconnected right side of the pump hose. Initially there was no liquid but you can here air venting and sound of the pump changed and realized coolant was finally present in the pump. I put the hose back on and let the purge system to run. I've noticed on the coolant reservoir by the passenger side, air bubble coming out and coolant going down so as it was purging I've added more coolant. After purge was done, went out for test drive and everything seems ok. Will update after more driving. Thanks everyone for your feedback.

 

[asavage]

Yup. As mentioned in the link Matt provided, the "Coolant Air Purge" procedure (32 minutes) is not 100%. For me, I'm blaming my issue on not having the car level, but it may be finickier than that; I've only had to use it for two repairs, and it worked OK for purging after R&R the OBC to replace its fuses. But it did not work OK for the LDU R&R.

 

[califteacher]

Thanks to everyone who contributed to this thread. It was fascinating to read and view the detailed photos. While I know that I could never do this type of repair, it was certainly informative. I can now better appreciate the complexity of these vehicles.

 

[asavage]

The LDU's common failure points (so far) are reasonably well documented, and the Tesla Model S/X crowd are ramping up for thousands of repairs of LDUs, so much information is available.

• Original rotor bearings w/steel balls
• Rotor seal leaks coolant, over and over and . . .
• HV cable gland leaks rain/snow melt

Most of the other issues with LDUs are variations due to the above + time/abuse. Very occasionally someone will break the differential, but no more than other diffs that are abused. They don't just fail in your driveway, as the rotor seal can.

My full tale of the "coolant delete" process, less R&R of the LDU, is here.

Getting the LDU in/out of a RAV4 EV is much easier than in the Model S/X; it can be done with a floor jack, though making a cradle is much more controllable, and I bought a sort of table lift to do mine, that is really not needed, but made an excellent standalone/stowable workbench, as it raises to 33", from 3".

More pics of it in use are here.

Overall, given just a few tools, many LDU repairs can be done easier than replacing a (commonly bad) CVVT gear on a Hyundai Elantra -- a project I may get roped into doing soon for a friend's car.