Megohmmeter - Loss of Isolation Diagnostics

Alligator clip, attach it to the chassis and we'll take our meter with the probe tip and test each of the positive and negative leads there, so I'll go in and touch, not pierce or probe the positive. side and then press the button and notice that it shows over 550 megohms with 527 volts applied now let's do the negative side here we go over 550 million ohms with five hundred twenty seven volts applied so if there was a short in either of these two wires to the chassis would have appeared now because if I put this meter probe in the chassis connection and press the button I get zero megohms and then if I have a fully open circuit like now, if I press the button it also gives me the five hundred and fifty mega ohms , which shows us that now we have an open circuit which is just the wiring from the distribution block to the air conditioning compressor module, where it takes DC, converts it to AC and has its Our small three phase motor inside the air compressor conditioned and we can't test that part of the circuit, but you can have the ability to turn it on and off with the scan tool and do some testing that way, very good, my The main point I wanted to show you here with this meter is that you can use it to test using high voltages to test resistances and the specifications in the GM service manual, all other Toyota, will give you a minimum resistance that each circuit, if any.

In good condition you should have it and if it is lower than that then you need to dig deeper and see what the problem is. Okay to conclude this video. I asked at the beginning of the video how safe we ​​are with an electric vehicle if it gets messed up. an accident and some of the high voltage circuits are trapped in the chassis or compressed together and I have shown you what happens or told you what happens in that case, we have analyzed several different resistance values ​​that simulate different levels of short circuits to the chassis from the high voltage systems and I've shown you what a glass of water does, it acts like a direct short circuit and we've talked about keeping moisture in, keeping parts sealed, keeping moisture out of things, especially as they get old.

They become more conductive and can cause

loss

of oscillations. It is important to keep adequate foods and liquids in your vehicle. Additionally, all fluids are not created equal. You need to have the exact prescribed fluids installed, including antifreeze, transmission fluid, air conditioning compressor oil, and So we've seen that we can activate and clear trouble codes. There are some trouble codes that won't go away until you have a special scan tool function to clear them and I've shown you just a little of what the

megohmmeter

can do. I'm going to have a separate video on how to use the megger to perform insulation

loss

diagnostics

and other things, so thanks for watching, have a good day.