Checking of Isolation Resistance between the stator to Chasis use Megaohmmeter
https://alflash.com.ua/2019/to_rav4ev/isolat_resist.png
https://alflash.com.ua/2019/to_rav4ev/isolat_resist.png
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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?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 . . .
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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.
It is impossible to measure the actual active resistance of the stator windings using a conventional DVOM tester.... I am getting continuity on all three leads of the stator(1-2, 1-3,2-3). Is this normal?
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