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.