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DIY: Roadster 2.5 PEM cleaning - step by step

Based on what Mark did and other pieces of information I could find on this forum, I decided to clean my PEM. Enjoy and use at own risk.

  1. Open your doors and windows. After you shut down the systems, none of them function.. I had to open the door via the bottom :)
  2. Enter the "Diagnostics menu", go to "Controls" and select "Inhabite APS". Confirm with YES. You should get the message "APS: APS power inhibited".
  3. Disconnect the APS 12V connector from PEM. This is the black connector in the picture below.
    19827211785_1b75e880f0_c.jpg
  4. Remove 4 screws securing the access panel to PEM. These are Torx TT20.
  5. Remove panel and lift up the safety label. You might want to take a picture here for later reference.

    19819948462_19b925e86a_c.jpg
  6. Check for voltage between the "B+" and "B-" labelled cables using a multimeter. I can't stress enough how important this step is. Residual voltage of 1 or 2V is to be expected. In doubt, do not proceed!
  7. Remove the EV inlet pilot connector (purple cable with white connector, most left in picture above).
  8. Remove nuts and washers from "B+" (13mm) and "B-" (10mm).
  9. Remove nuts and washers from "B+ GND" (10mm) and "B- GND" (10mm).
  10. Remove black plastic insulators from "B+" and "B-" cables.
  11. Loosen cable gland nut and remove rubber grommet from the 2 upper cables.

    19206387893_0ee4ca5347_c.jpg
  12. Withdraw the 2 upper power cables.
  13. Collect the Toroid choke and put aside. Don't forget this when you put everything back together!
  14. Remove nuts and washers from the 3 charging cables (Black and Red are 13mm, Green is 10mm). You might want a picture of this too for when you put it back together.

    19640713859_fdeb5fb40e_c.jpg
  15. Loosen cable gland nut and remove rubber grommet from the last cable.
  16. Release the cable from PEM.
  17. Remove the bolt securing the coolant tank (Phillips screwdriver).
  18. Disconnect the ground strap from body, 10mm nut located just under the coolant tank.
  19. Remove 4 screws securing the trunk access panel to PEM (Phillips screwdriver), then remove the panel.
  20. Remove 4 screws securing the warning panel, then remove the panel. The screws stay in the panel.

    19832175951_6bc5ef3bb7_c.jpg
  21. Remove 2 nuts securing the cable clamp (7mm). In the middle of next picture:

    19206406683_8d03e2abcc_c.jpg
  22. Remove the front of the cable clamp and put 1 of the nuts from previous step back to secure the back of the clamp.
  23. Remove 3 cable terminal screws and washers (6mm Allen key) as seen in following picture. Note the cable colors, mine were pink-black-blue. Then slide the cables out and pay attention to the shape of the rubbers.

    19827350885_1cb2865382_c.jpg
  24. Remove 3 bolts on both sides, securing the PEM to the body (8mm).
  25. Now you can position something between the PEM and rear bulkhead to prevent paint damage. We were careful enough not to touch anything, but better be safe than sorry.
  26. Remove the bolts securing the RH side of PEM to body, then the bolt securing LH side. Both are 13mm.
  27. Lift the RH side of the PEM and support on a block of about 7cm high.
  28. Working through the trunk and from RH side of PEM, remove the 4 connectors from under the PEM. Note that the first 2 connectors (from left to right) have a lip that you need to lift before you can remove them, and the last connectors have the same mechanisme as the APS connector from step 3.

    This is how they look like installed:

    19204720864_4c898f68ae_c.jpg


    For reference, this is how they look like cleaned up:

    19640757729_d22e3bf13e_c.jpg
  29. Lower the RH side of the PEM, then lift the LH side of the PEM. Support again on a block of about 7cm.
  30. Pull the clip, located at the rear left corner of the PEM, and simultaneously slide the PEM cooling duct intake inboard to release the connecting tabs. Once the PEM is out, have a good look at how this works as you'll need that info for reassembling.

    19640764659_34525c4372_c.jpg
  31. Now lift the PEM out and start cleaning. I had the best success with an air gun and some 45 minutes of hard labor. Then another hour to clean the motor and bay. I also opened the 2 screws on top of the motor and sucked as much dust and leaves out as possible.

    This was the result:

    19206430523_f320f28760_c.jpg


    19206425363_78ef7f3616_c.jpg


I would rate this difficulty: 5/10. It's just following a procedure and making sure you don't drop any nuts :)


Mod Note: One of our other members posted a YouTube video on the process, which is a good compliment to this procedure. See Roadster Rear Blower Maintenance - Page 7
 
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I will update the images later, also before and after of the cleaning. The most dirt came out of the cooling banks, the problem is not the inlet getting blocked, but the overheating starts when the start of a cooling bank gets blocked. Then the whole bank gets isolated. I will document this too. Last but not least, I inspected the tube between fan motor and the PEM cooling duct. It's a poor design and I will upgrade it next time.
 
I believe this post with Mark's video also belongs very well here!

Hi everyone.

I have prepared a video to help those of you wanting to do your own PEM clean. We did ours last week, and while it was a bit more than changing a bulb, it was nothing crazy. I suspect I could get the job done in a couple of hours in the future.

Tesla Roadster V2.5 PEM Cleaning - YouTube

Hope this helps you all.

It didn't just fix the power limit issues but it also managed to improve performance mode in so much as the word "Performance" is almost always in white now. It hasn't been that way since the first year!

When it comes down to things, I suppose I am willing to spend hours cleaning the PEM if that is what it takes. I can only imagine that the Tesla service giuys are running to a schedule and can't be so rigorous.

Anyway, good luck to you if you are doing this and let me know if there are any mistakes I made.

Cheers

Mark
 
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hcsharp

Active Member
Jun 7, 2011
3,485
1,604
Vermont
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 believe this post with Mark's video also belongs very well here!

Indeed! He has been very influential ;)

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.

Now I keep thinking: Why on earth did I not open that cover myself? :D
 

dhrivnak

Active Member
Jan 8, 2011
4,639
4,184
NE Tennessee
I just cleaned my 1.5 PEM and while similar it is different. The high voltage connectors have a nice twist connector, which is good. But they are not easy to get to, bad. This one is about 8 inches in under the PEM with very little clearance.
PEM_Cleaning_06.JPG
There are two 13mm nuts you have to remove from the underside with a 24" extensions, so it really helps for the car to up on ramps or jack stands.
PEM_Removal (1).jpg
Then I saw one ranger use some wood block "jigs" that you can use to get the PEM up so you can reach the connectors as you do not have a little door to reach into from the trunk. It gives just enough space to reach in and twist off, assuming you do not have large hands. The wood blocks are from a 2x4 cut 6" long.
PEM_Removal (4).jpg
It took me 4 hours, so while it saved me money it was not easy. I got very little dirt from the PEM and motor so I could likely go two years between cleaning as my PEM seems to stay quite clean. My baffles to keep the dirt out seem to be working well.
 
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The 1.5's for sure take in very minimal dirt. Did you wash / clean the motor fins while you were in there? I know you fabricated a custom shield which limits how much dirt your blower pulls in, so you should be ok there. On the 1.5 I feel that is the main component that'll take in the most grime & debris since its fed by the lower blower unit. As we know the 1.5 PEM has a fan up high that pulls relatively clean air into the PEM's cooling fins. Pulling air from down low is bad and the 2.x's have shown.

Note, when anyone does maintenance such as the PEM and motor cleaning, take PEM and motor temps after its been cleaned. Also take down the ambient temp, this is key. Then use these temps as a gauge as when you need to do your next cleaning but target a day when the ambient temps (as well as humidity) is the same or close to your initial benchmark. I suggest a reading when everything has been warmed up but at highway speeds, not pushing the Roadster. Then another reading when you hammer the Roadster getting things to spike. As cooling / components gets restricted, you'll see these temps rise. If you do your own service, you can then use what you see in terms of dirt / build up to relate when you need to address the next service and so on.

I'm at the 2 year mark I believe since I did my last cleaning, temps are looking good. I drove on one dusty dirt road, drove very very slow so I would minimize the amount of dust being pulled into the PEM/Motor. Temps haven't risen, so I should be still good. I may push out to 3 years for my next cleaning unless I get bored and some free time. I don't see a need to take things apart right now.

Also with the 1.5 connectors, I recommend taping the CF that's around the connector. The connector since its a bear, will bang / hit the CF and chip it. If you put tape there it absorbs the shock.

Lastly should we merge your PEM cleaning, rename the title to "1.5 PEM cleaning" and combine my as well as your PEM how-to's together? I feel we should leave this one as a 2.x PEM cleaning so people can stay on track with what they have.
 
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dhrivnak

Active Member
Jan 8, 2011
4,639
4,184
NE Tennessee
Also with the 1.5 connectors, I recommend taping the CF that's around the connector. The connector since its a bear, will bang / hit the CF and chip it. If you put tape there it absorbs the shock.

Lastly should we merge your PEM cleaning, rename the title to "1.5 PEM cleaning" and combine my as well as your PEM how-to's together? I feel we should leave this one as a 2.x PEM cleaning so people can stay on track with what they have.

Thank you Wiztec and you are absolutely correct about the tape on the carbon fiber by the connectors. I did do that and did do that but forgot to mention and yes it would be nice to have two threads as the PEM removal is a good bit different. I agree it seems the design of the 1.5 keeps the PEM much cleaner. While I did get a little dust out of the PEM and motor it was quite minimal for a year and 8000 miles. I think ever 2nd or third year would be fine and save wear and tear getting the PEM out as it is quite a tight fit.

On the motor fins I am not sure what you are talking about as it seems my motor has a shroud and like the Rangers before me I just cleaned it out with compressed air.

PEM_Cleaning_09.JPG
 
The pic you have above, the bronze looking thing is a *very* fragile cover that helps direct the airflow from the lower blower unit up to the bottom side of the motor which exits left at the gearbox area where all the perforations / holes are. Note no perforations are on the right, so its forced out the left which has the least resistance. The bronze cover is brittle due to poor choice of materials / plastic that breaks down with heat, and we know the motor generates that and the shroud is to capture and help create a forced directional air-flow to exit the heat with the induction of airflow with the blower's help.

The cowl comes off by loosening/removing the large SS hose clamps in the middle there and cutting a few zip-ties which some wires / grounds are hooked onto as a means to keep things tidy, and popping out the black round securing nipple that's in the right side of your pic.

I'm a huge fan of keeping things clean when its all apart, so sponge down / take the time to wipe the dirt/dust off. Dirt/dust will cling to clean surfaces (static bond) of things rather than getting pulled into the PEM, if there's a bunch of dirt on the surfaces of things, back side of ESS, gearbox, frontside of the trunk area, it has more chance of floating around and finding a spot to bind or bond with such as your PEM. I always hose off my under-tray and diffuser where the rear blower is for that very reason. Lastly I clean the blower and all the ducts, most importantly inside of them, to ensure a clean and optimal operable environment.


Gearbox side of the electric motor cooling fins, they're the zig-zagged fins on the outside perimeter of the housing.

tesla-roadster-5.jpg




Here is the passenger side view of the motor and fins, take note the black rubber duct. This is a 2.x implementation of the cooling cowl which the 1.5 has in a brittle bronze hard plastic. The 2.x uses a flexible rubber cowl which is overall a better implementation for that it won't crack due to being brittle. Note over-time rubber can dry out and crack, but it takes some time, heat, and typically bad design of the materials as well.

motor-01.jpg
 
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While you have the PEM out I suggest a person visually inspect the connectors and pins for the blower motors. This is the connector on the passenger side (underneath). Mine failed, specifically the PEM blower connection. This generated errors 1144 and 1146. The PEM gets hot and shuts down. Unfortunately, the mating half (male) on the PEM was also damaged by the heat. That one is a right angle connector soldered to a PCB deep in the PEM. The parts are Molex connectors and are readily available from electronic supply houses for just a few dollars. While researching these I found out that they are rated for 18 amps and a max of 25 cycles. I measured the draw on my fan (upgraded single motor) and found it draws 15 amps with a start surge of 45 amps. The old dual motor fans draw 14 amps and the start up surge was 25 amps. Clearly the connector is marginal for this application. The fuse on the circuit is 20 amps and is located just under the cover of the PEM.

image.jpeg
 
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ecarfan

Well-Known Member
Moderator
...That one is a right angle connector soldered to a PCB deep in the PEM. The parts are Molex connectors and are readily available from electronic supply houses for just a few dollars. While researching these I found out that they are rated for 18 amps and a max of 25 cycles. I measured the draw on my fan (upgraded single motor) and found it draws 15 amps with a start surge of 45 amps. The old dual motor fans draw 14 amps and the start up surge was 25 amps. Clearly the connector is marginal for this application.
Please define the term "cycles" as you are using it in your post. I don't know what that means. Obviously it cannot mean "on/off" cycles.
 

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