I thought I would share my story of the successful DIY PDM replacement on my 2013 Nissan Leaf with about 70K miles, only occasionally fast charged. This was back in March, so memory of details is fading...
Here are the highlights. Remember: possible high voltage, don't try this at home unless you have proper tools and training. at your own risk if you try this. i.e. don't be dumb like me and leave it to the pros.
The Problem: After brief charging session at a Evgo charging station which seemed to go normally, the car would not go into drive. Dash lit up like christmas tree. Since 12V battery was iffy, and that can cause various problems, I replaced with a new/charged 12V battery. Still no go. Had car towed home.
Diagnosis: I tried clearing codes with LeafSpy pro. Removed 12V for several minutes, etc. No go. Had car towed to dealership which diagnosed (correctly) bad PDM.
Repair options: First quote from Nissan dealership to replace was $4400 (San Jose, California). I talked them down a bit -- can't remember final price but north of $3500 for sure. I found another place in town that specialized in hybrids and EVs which quoted around $3K. New PDM from Nissan was $2250. I found used PDMs for sale online (car-part.com) and ebay, ranging from $300-$1000. Decided to replace myself with used PDM and had it towed back home.
Finding Used PDM: This took a while, and some luck. In general the used-parts databases don't handle EV parts like PDM well. They standard used-parts databases seem to be used by all the salvage yards, and they don't have category for "PDM". So this creates a lot of confusion. I would often find the part listed as "inverter" (which is not the same part), and would need to go by photo or part number given. Further confusion because of the various versions and revisions of the PDM. The original part was 28C20-3F3A. Current replacement part from Nissan is 28C20-3F7D, which is listed as replacing 3C, 7C, 3A, 3B, 7A, 3D and 3E. Does that mean all of those are compatible ? who knows ? After many wild goose chases I found a place that would ship to the door of residential house a PDM, with all the HV cables, for $430! I could not get the exact part number, the the car serial number was for a 2013 SL (which means fast charging) and they sent some photos that looked OK, but not 100% clear. I rolled the dice and ordered it... but when it arrived the car serial number did not match, and it came from a base (not SL), but it did have fast charging, and it came with all the HV cables attached. It was a 7B version -- would it work -- only one way to find out... I thought I would be able to swap out without opening the PDM (later found this was wrong due to heater cable, more details below).
PDM Removal: Disclaimer: Don't try this at home, risk of electrical shock. Found some PDFs of nissan repair manual online and watched some youtube videos. I removed it (without opening PDM) along with the HV cables. Quite a bit of work. I don't remember now, but my shade-tree mechanic work/tools/experience took me probably all day. Disconnect 12V. Pulled the HV plug. Checked no HV anywhere. Removed Hood, cowl, wipers, under car plastic covers, carefully drained coolant to reuse, and much much more. Used mityvac to suck out as much coolant as I could. Working alone and I did find I needed to use an engine hoist to get it out.
Replacement vs Original PDM: The bad news... After comparing replacement to original, I realized I would have to open the PDM (sigh). This is because since they did not send me the PDM from a 2013SL as I ordered, but instead a base car, the heater cable was different (my car has heat-pump setup, which uses different cable). At least I was lucky that it was a fast-charge PDM. If I would have known I was going to have to open the PDM, it could have saved time on removal, because I could have left HV cables in car. I had to open the replacement PDM (take off sealed top cover) and swap the heater cable -- again luckily the hook-up was the same internal to the PDM. Swap went well but added work because it was difficult to remove cover due to sealant -- needs to be done carefully to not crack aluminum while prying. Then carefully removing old sealant without contaminating PDM guts, and then re-installing cover with new sealant. Hours of work.
Installing PDM: as I recall pretty much reverse of removal. The PDM needs to be installed carefully so as not to bend the bus bars the connect to PDM to inverter, again I doubt it could be done without and engine hoist, especially with one man. I improvised some guide pins that went into the bolt holes on the inverter to guide the PDM into place as it was lowered. Tried to get the bus bar bolts torqued per manual specifications. Then just reversing the process of the removal. A lot of tight access for the HV cables clips and some of the bolts accessed between PDM and firewall, but I managed to get them in. Remember to refill the coolant -- I was able to reused (filtered through paper towel) the coolant that a drained during removal.
Start-up: Memory a little fuzzy, but I think I cleared all the codes one more time with leafspy pro, and car worked! I've been driving for several months now. I have briefly fast-charged a couple of times.
Failure analysis: While I had the PDMs out, and since I had to take the covers off to swap the heater cable, I was able to do some inspection/analysis. I found that both of of the HV contactors to the fast charge cable were stuck closed (shorted). I compared to the replacement where both contactors were open as expected. I suspect the only problem with the old PDM were these two contactors. I was surprised that _Both_ were bad. I suspect that when the car boots up it checks that there is no HV at the connector side of the fast charge connector. My guess is this check will only fail if both contactors have shorted, as was my case. I have dismantled one of the contactors and the internal contacts did not look too bad, but I suspect they must have arced enough to get stuck shut -- IMHO some type of design problem that this would happen, especially considering the car had not been fast charged much.
In hindsight: Since it looks like the contactors were the problem, a potentially easier repair would have been just to replace one or both of the contactors, although Nissan doesn't sell them nor did I find them for sale on ebay, so probably I would have had to bought an entire PDM anyway. Another possible fix (untested) would have been to simply disconnect the bus bars from the relays inside the PDM -- this would have kept HV from reaching the fast-charge connector, which I suspect would have allowed the car to pass the startup self tests -- of course this would also mean that fast charging wouldn't work, but that might have been ok for me -- I rarely ever fast charge anyway... if I ran into this problem again I might try testing/disconnecting the contactors as an at least short term solution.
Final overall cost: Probably around $1000. Car towed 3 times (home, to dealership, from dealership) : $450 total. $430 for PDM -- delivered! Nissan shop diagnosis cost ($250?). New 12V battery (around $200?) -- probably not needed, but it was about time anyway. I already owned the $1000 in tools, hoist, jacks, etc used. the car was down for probably about 3-4 weeks. I probably put in two weekends doing all the wrenching work. plus numerous hours researching and tracking down replacement PDM.
Anyway, that is my story. I thought I would share in case it might be useful or interesting to anybody out there. I've summarized the experience above, but if somebody wants more details let me know and I'll try to respond. I do have some photos I took along the way if anybody is interested.
Thanks to others that posted their PDM stories here on mynissanleaf.com, which helped in the process. Also thanks to Dala of Dala's EV Repair on youtube -- Dala's videos were especially helpful, and he even responded to a question I sent him.
Here are the highlights. Remember: possible high voltage, don't try this at home unless you have proper tools and training. at your own risk if you try this. i.e. don't be dumb like me and leave it to the pros.
The Problem: After brief charging session at a Evgo charging station which seemed to go normally, the car would not go into drive. Dash lit up like christmas tree. Since 12V battery was iffy, and that can cause various problems, I replaced with a new/charged 12V battery. Still no go. Had car towed home.
Diagnosis: I tried clearing codes with LeafSpy pro. Removed 12V for several minutes, etc. No go. Had car towed to dealership which diagnosed (correctly) bad PDM.
Repair options: First quote from Nissan dealership to replace was $4400 (San Jose, California). I talked them down a bit -- can't remember final price but north of $3500 for sure. I found another place in town that specialized in hybrids and EVs which quoted around $3K. New PDM from Nissan was $2250. I found used PDMs for sale online (car-part.com) and ebay, ranging from $300-$1000. Decided to replace myself with used PDM and had it towed back home.
Finding Used PDM: This took a while, and some luck. In general the used-parts databases don't handle EV parts like PDM well. They standard used-parts databases seem to be used by all the salvage yards, and they don't have category for "PDM". So this creates a lot of confusion. I would often find the part listed as "inverter" (which is not the same part), and would need to go by photo or part number given. Further confusion because of the various versions and revisions of the PDM. The original part was 28C20-3F3A. Current replacement part from Nissan is 28C20-3F7D, which is listed as replacing 3C, 7C, 3A, 3B, 7A, 3D and 3E. Does that mean all of those are compatible ? who knows ? After many wild goose chases I found a place that would ship to the door of residential house a PDM, with all the HV cables, for $430! I could not get the exact part number, the the car serial number was for a 2013 SL (which means fast charging) and they sent some photos that looked OK, but not 100% clear. I rolled the dice and ordered it... but when it arrived the car serial number did not match, and it came from a base (not SL), but it did have fast charging, and it came with all the HV cables attached. It was a 7B version -- would it work -- only one way to find out... I thought I would be able to swap out without opening the PDM (later found this was wrong due to heater cable, more details below).
PDM Removal: Disclaimer: Don't try this at home, risk of electrical shock. Found some PDFs of nissan repair manual online and watched some youtube videos. I removed it (without opening PDM) along with the HV cables. Quite a bit of work. I don't remember now, but my shade-tree mechanic work/tools/experience took me probably all day. Disconnect 12V. Pulled the HV plug. Checked no HV anywhere. Removed Hood, cowl, wipers, under car plastic covers, carefully drained coolant to reuse, and much much more. Used mityvac to suck out as much coolant as I could. Working alone and I did find I needed to use an engine hoist to get it out.
Replacement vs Original PDM: The bad news... After comparing replacement to original, I realized I would have to open the PDM (sigh). This is because since they did not send me the PDM from a 2013SL as I ordered, but instead a base car, the heater cable was different (my car has heat-pump setup, which uses different cable). At least I was lucky that it was a fast-charge PDM. If I would have known I was going to have to open the PDM, it could have saved time on removal, because I could have left HV cables in car. I had to open the replacement PDM (take off sealed top cover) and swap the heater cable -- again luckily the hook-up was the same internal to the PDM. Swap went well but added work because it was difficult to remove cover due to sealant -- needs to be done carefully to not crack aluminum while prying. Then carefully removing old sealant without contaminating PDM guts, and then re-installing cover with new sealant. Hours of work.
Installing PDM: as I recall pretty much reverse of removal. The PDM needs to be installed carefully so as not to bend the bus bars the connect to PDM to inverter, again I doubt it could be done without and engine hoist, especially with one man. I improvised some guide pins that went into the bolt holes on the inverter to guide the PDM into place as it was lowered. Tried to get the bus bar bolts torqued per manual specifications. Then just reversing the process of the removal. A lot of tight access for the HV cables clips and some of the bolts accessed between PDM and firewall, but I managed to get them in. Remember to refill the coolant -- I was able to reused (filtered through paper towel) the coolant that a drained during removal.
Start-up: Memory a little fuzzy, but I think I cleared all the codes one more time with leafspy pro, and car worked! I've been driving for several months now. I have briefly fast-charged a couple of times.
Failure analysis: While I had the PDMs out, and since I had to take the covers off to swap the heater cable, I was able to do some inspection/analysis. I found that both of of the HV contactors to the fast charge cable were stuck closed (shorted). I compared to the replacement where both contactors were open as expected. I suspect the only problem with the old PDM were these two contactors. I was surprised that _Both_ were bad. I suspect that when the car boots up it checks that there is no HV at the connector side of the fast charge connector. My guess is this check will only fail if both contactors have shorted, as was my case. I have dismantled one of the contactors and the internal contacts did not look too bad, but I suspect they must have arced enough to get stuck shut -- IMHO some type of design problem that this would happen, especially considering the car had not been fast charged much.
In hindsight: Since it looks like the contactors were the problem, a potentially easier repair would have been just to replace one or both of the contactors, although Nissan doesn't sell them nor did I find them for sale on ebay, so probably I would have had to bought an entire PDM anyway. Another possible fix (untested) would have been to simply disconnect the bus bars from the relays inside the PDM -- this would have kept HV from reaching the fast-charge connector, which I suspect would have allowed the car to pass the startup self tests -- of course this would also mean that fast charging wouldn't work, but that might have been ok for me -- I rarely ever fast charge anyway... if I ran into this problem again I might try testing/disconnecting the contactors as an at least short term solution.
Final overall cost: Probably around $1000. Car towed 3 times (home, to dealership, from dealership) : $450 total. $430 for PDM -- delivered! Nissan shop diagnosis cost ($250?). New 12V battery (around $200?) -- probably not needed, but it was about time anyway. I already owned the $1000 in tools, hoist, jacks, etc used. the car was down for probably about 3-4 weeks. I probably put in two weekends doing all the wrenching work. plus numerous hours researching and tracking down replacement PDM.
Anyway, that is my story. I thought I would share in case it might be useful or interesting to anybody out there. I've summarized the experience above, but if somebody wants more details let me know and I'll try to respond. I do have some photos I took along the way if anybody is interested.
Thanks to others that posted their PDM stories here on mynissanleaf.com, which helped in the process. Also thanks to Dala of Dala's EV Repair on youtube -- Dala's videos were especially helpful, and he even responded to a question I sent him.
