DIY: Roadster 2.5 PEM cleaning - step by step

[PV-EV]

25 cycles is the mechanical specification of the connectors' durability. Current would be zero.

http://rhu004.sma-promail.com/SQLImages/kelmscott/Molex/PDF_Images/987650-2181.PDF

 

[slcasner]

25 cycles is the mechanical specification of the connectors' durability. Current would be zero.

Right, so that is just specifying that the tin plating can stand 25 insertion/removal cycles before it wears off. That's not a lot, but shouldn't be a problem unless the PEM is removed many times. That spec should be unrelated to how much current the connection can handle.

 

[dhrivnak]

Right, so that is just specifying that the tin plating can stand 25 insertion/removal cycles before it wears off. That's not a lot, but shouldn't be a problem unless the PEM is removed many times. That spec should be unrelated to how much current the connection can handle.

But at a recommended cleaning of once a year we are talking about 25 years. Less than most cars I see at the local car shows.

 

[PV-EV]

Right, so that is just specifying that the tin plating can stand 25 insertion/removal cycles before it wears off. That's not a lot, but shouldn't be a problem unless the PEM is removed many times. That spec should be unrelated to how much current the connection can handle.

I'm not sure where you get the idea that the tin is wearing off. It is more likely due to the fit between male and female parts becoming sloppy after multiple insertions. This leads to a higher resistance connection which would cause more heat and potentially burn the contacts. The amount of heat is proportional to the current squared. Take a look at the photo I posted. My connector was cycled approximately 8 times. The spec sheet says 25 MAXIMUM, it doesn't list a minimum number. What would you expect from a pair of connectors that cost less than $10? And the consequences of failure? My wife was stranded on her way to the OR. The service center said NEW PEM. That's $9700 plus labor in case you haven't been paying attention, not to mention loss of all good husband points recently accumulated. Replacement female contacts cost $.92 for 4 plus shipping. That's 92 pennies. I will be changing out the female pins on mine and applying electrical antioxidant before reassembly each and every time I pull my PEM. The cost of another failure is just too high and the cost and effort of the preventative maintenance ridiculously low.

 

[slcasner]

I'm not sure where you get the idea that the tin is wearing off. It is more likely due to the fit between male and female parts becoming sloppy after multiple insertions.

I don't dispute the fit problem, but the metal underlying the tin plating is the same in the version with gold plating. Since the gold plating is rated 100 cycles, that must mean that excess distortion of the underlying metal does not occur in 25 cycles.

 

[hcsharp]

I'm not sure where you get the idea that the tin is wearing off. It is more likely due to the fit between male and female parts becoming sloppy after multiple insertions. This leads to a higher resistance connection which would cause more heat and potentially burn the contacts. The amount of heat is proportional to the current squared. Take a look at the photo I posted. My connector was cycled approximately 8 times. The spec sheet says 25 MAXIMUM, it doesn't list a minimum number. What would you expect from a pair of connectors that cost less than $10? And the consequences of failure? My wife was stranded on her way to the OR. The service center said NEW PEM. That's $9700 plus labor in case you haven't been paying attention, not to mention loss of all good husband points recently accumulated. Replacement female contacts cost $.92 for 4 plus shipping. That's 92 pennies. I will be changing out the female pins on mine and applying electrical antioxidant before reassembly each and every time I pull my PEM. The cost of another failure is just too high and the cost and effort of the preventative maintenance ridiculously low.

I would think the fit between contacts is established with spring-loaded female contacts. I'm not sure that would become sloppy as a result of repeated matings. I would be more inclined to suspect the cycle rating is based on the plating they used, like it is with most connectors. But I can't claim to know for sure.

I think you're right that the current is a little high considering the capacity rating. Personally I doubt the plating is wearing off or the fit is becoming sloppy after so few cycles. I suspect it's dirt and/or corrosion. When cleaning a PEM there is dirt blown everywhere. Compressed air is pretty much required to do a good job. Some of that airborne dirt no doubt gets into the connectors and severely compromises their capacity.

Are you going to replace your PEM or attempt to repair it? That circuit board with all the connectors requires that you dismantle almost everything to get to it.

 

[ML Auto]

It would be much easier to solder extension wires directly on the PEM terminals and use a better connector. Probably good preventive maintenance next time my PEM is out.

 

[PV-EV]

Are you going to replace your PEM or attempt to repair it? That circuit board with all the connectors requires that you dismantle almost everything to get to it.

I soldered a pigtail on the PEM for now. I agree that the connector is buried too deep for easy repair. Hope to put it back together this weekend and try her out.

 

[Rolf68]

Good morning everybody.

Thanks a lot for this interesting tutorial. I might give it a try this summer, but I'm puzzled by the first step. How do you go in the "diagnostic mode" ? I never saw anything like that in the roadster menu. I have a 2.5 if that helps.

Thanks

Enter the "Diagnostics menu", go to "Controls" and select "Inhabite APS". Confirm with YES. You should get the message "APS: APS power inhibited".

 

[hcsharp]

After disabling APS, make sure you don't close the door.

 

[wiztecy]

After disabling APS, make sure you don't close the door.

If you do, all you need to do is insert the key into the key slot located underneath the door. When you turn it the door will open even though power is cut.

 

[ElectricLove]

I usually leave my key on the seat of car or in dash... So if you do disable the APS and close the door and have the top on and have the key inside; you are going to panic... for a moment! then you will recall that opening and closing the charge port door ~7 times in succession reboots the VMS and will also consequently uninhibit the APS, handy feature to know about in this scenario where you would otherwise be completely screwed...

 

[ML Auto]

If you do, all you need to do is insert the key into the key slot located underneath the door. When you turn it the door will open even though power is cut.

If you didn't leave the key in the ignition. And only have one key.

 

[Rolf68]

Thanks for the extra tip to let the door opened If you just leave the windows open can you manually open it from inside or do you need tu use the key under the door anyway?

 

[dhrivnak]

Yes if the window is down you can reach in and open the door.

 

[Rolf68]

Yes if the window is down you can reach in and open the door.

Thanks for the answer.

 

[mckee]

Good morning everybody.

How do you go in the "diagnostic mode" ? I never saw anything like that in the roadster menu. I have a 2.5 if that helps.

Can someone please clue me in on this little bit as well? The PEM on my roadster has been running warm while driving through hills and my guess is its about time to give it a little TLC.

 

[scotty2541]

Awesome.... and timely. My service is due.

 

[thefortunes]

So...I did this self-service PEM/motor clean last night.

After 4 hours and the removal of a lot of dust and some shredded leaves and grass my PEM and motor are both happier. The PEM temp is running 10degC lower, I'll have to check the logs for motor temp improvement. Both were at the 4th indicator prior to the service, they are now running 2nd-3rd indicator after the service (same commute, reasonably close ambient temp).

I would agree with m0rph's assessment - it is not a difficult task (thanks to his excellent instructions) as long as you methodically follow instructions and don't drop any nuts .

The only thing I would add is that I blew compressed air through the fans (and therefore through the duct) when everything was out and it sent some additional dust/leaves skyward. Can't hurt to get as much as possible out of that duct before you put it all back together.

 

[Perrin21]

Very nice instructions and pics. I also removed the 4 screws from the small plastic cover that sticks up on the bottom of the PEM. You can see this cover in step 31. It has an air duct under it and mine was full of dirt. It would also be nice to see a pic of the small PEM mounting screws and the larger ones in front. Thanks for doing this.

I wonder if that cover would benefit from being deeper and larger? it gets really blocked up. Maybe someone with a 3d printer could make a bigger one.