Gen 5 Rav4 Hybrid High Voltage Wiring Corrosion

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We are thinking of replacing my wife's Outback with a Rav4 Hybrid. I came across this article (it's in french, but google will translate):


It speaks of some serious wiring corrosion issues with the high voltage wiring to the rear motor. To replace this harness is somewhere north of $5K! Toyota has issued a TSB for 2019-2020 models, which the newer Hybrids have an updated connector design. I am not sure if the new design is a long term solution as it still appears corrosion could be an issue with time. I also came across this thread on a RAV4 forum which has some good pics and shows the old connector vs the new connector and reports of others with the same problem.


It seems this is an issue on Rav4 Hybrids in areas of inclement weather and the use of road salt. The replacement of the harness is only covered under the basic 3 year 36K warranty not the longer hybrid or powertrain warranty. My wife previously owned a Gen III Prius, that was pretty bulletproof, but the Rav4 Hybrid has me somewhat concerned as we live in an rural area with lots of snow, salt and sand. Toyota replaced the frame on my friend's 16 year old Tacoma last year, so it seems odd that they are not stepping up to the plate on this. And it also is disappointing that they haven't come up with a better designed harness connector to replace the original design.

This is the early design connector used on 2019-2020 (or so) Rav4s

Rav4 Connector 1.jpg


This is what happens after water, sand and salt get into the connector leading to harness failure.

Rav4 Connector 2.jpg


Here is the updated design, which is open. I guess the idea is to ensure no moisture builds inside, but I still see this not being a good design in the long run as the wiring strand is still exposed to the the elements.

Rav4 Connector 3.jpg
 
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ugh bad design there.
I already know how those will look after 5 years of salt here.
 
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Oldswagon

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ugh bad design there.
I already know how those will look after 5 years of salt here.
I agree, it is a bad design. It has me seriously hesitating on buying one, especially since we keep our vehicles for at least 5 years. Ever since these 5th gen Rav4 Hybrids came out if figured they were a good option for us. I have wanted to move my wife back into a hybrid for a while, and the Rav4 seemed like a good option after our positive experience with the Prius. I don't really want a straight gasser Rav4, as the fuel economy is probably marginally better than our current Subaru Outback.

Does anyone here think there is anything you can do to prevent this problem? I typically rust proof my vehicles with Krown, but I know Toyota doesn't recommend it with Hybrids. I am not sure if the Krown spray would help protect it, or maybe it would just cause excess dirt build up. We did rust proof our old Prius with no issues for the 5 years we owned it.
 
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I’d consider potting it - fill the entire back side cavity with epoxy.

or surround it with a shield, soup can!
 
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That updated part looks like it’s missing something but supposedly that is how it is installed? There is that slot thing on the bottom and the upside down U that looks like a holder for a hose.

If it’s not near anything hot would a piece of rubber work?

That exposed wiring is definitely waiting for problems to happen.
 

Oldswagon

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I’d consider potting it - fill the entire back side cavity with epoxy.

or surround it with a shield, soup can!
The epoxy idea might work, the only issue I see is it could void the warranty. I wouldn't want Toyota to extend coverage on this and then be not eligible due to my modifications. So I think making something like a surround or shield that is easily removable might be a better option. Toyota does have some underbody cover that is near it, but I guess it is ineffective. See this pic below:

20220318_170106.jpg



That updated part looks like it’s missing something but supposedly that is how it is installed? There is that slot thing on the bottom and the upside down U that looks like a holder for a hose.

If it’s not near anything hot would a piece of rubber work?

That exposed wiring is definitely waiting for problems to happen.

No I don't think anything is missing. I found the TSB and the picture below shows the old versus new connector. The exposed wiring is just the wire strand, which I assume is used for grounding. It obviously serves some function, because the corrosion does set DTCs and can cause a hybrid system malfunction. If you look closely, you can see the orange/green stipe high volage cables which have a sheathing. I found a the TSB in French. I can upload it, but it doesn't seem this forum will allow me to post a PDF?

New vs Old Connector.jpg
 
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The epoxy idea might work, the only issue I see is it could void the warranty. I wouldn't want Toyota to extend coverage on this and then be not eligible due to my modifications. So I think making something like a surround or shield that is easily removable might be a better option. Toyota does have some underbody cover that is near it, but I guess it is ineffective. See this pic below:

View attachment 96852




No I don't think anything is missing. I found the TSB and the picture below shows the old versus new connector. The exposed wiring is just the wire strand, which I assume is used for grounding. It obviously serves some function, because the corrosion does set DTCs and can cause a hybrid system malfunction. If you look closely, you can see the orange/green stipe high volage cables which have a sheathing. I found a the TSB in French. I can upload it, but it doesn't seem this forum will allow me to post a PDF?

View attachment 96853


It looks like they modified the previous mold to eliminate that section.

It might come down to costs but if the splash shield is in place then some drain holes or slots might work. I’m thinking this is a stopgap measure until they can come up with one that is much better suited to deal with the corrosion and debris.
 
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The epoxy idea might work, the only issue I see is it could void the warranty. I wouldn't want Toyota to extend coverage on this and then be not eligible due to my modifications. So I think making something like a surround or shield that is easily removable might be a better option. Toyota does have some underbody cover that is near it, but I guess it is ineffective. See this pic below:

View attachment 96852




No I don't think anything is missing. I found the TSB and the picture below shows the old versus new connector. The exposed wiring is just the wire strand, which I assume is used for grounding. It obviously serves some function, because the corrosion does set DTCs and can cause a hybrid system malfunction. If you look closely, you can see the orange/green stipe high volage cables which have a sheathing. I found a the TSB in French. I can upload it, but it doesn't seem this forum will allow me to post a PDF?

View attachment 96853
Oooooohhhhh that’s ground strands. Probably suggests that EMI frequencies off this thing are potent.
 

Oldswagon

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Oooooohhhhh that’s ground strands. Probably suggests that EMI frequencies off this thing are potent.
Yes I think EMI is an issue as apparently when the harness degrades, there is a loss of the AM radio signal. I am wondering of the corrosion in the connector also spreads to the main wires. It seems when it gets as bad as the example I posted, DTCs are set and the vehicle becomes disabled.

Use a re-enterable potting compound. It can be peeled away and removed after it is applied, if needed.
Where where you get this product?
 
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Is it that super-sticky clear gelatine-like grease that gets all over EVERYTHING?

No, that's a flooding compound, which is used in cables.

Re-enterable potting compound is usually a 2-part polyurethane with a very low shore hardness. Once it cures it is not very (if at all) sticky and doesn't flow. One such product is known as "high gel re-enterable encapsulant".
 
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Do not buy this car. If you must, get the longest optional factory warranty extension.
 
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