New Member 2014 Smart ED No Start No Charge
41 - 55 of 55 Posts
(I know the picture with the multimeter reading shows it set to 2M ohms range, that was just a quick picture, it reads open on all settings.)
Joined
·
14 Posts
Wow, you found it, good work. It appears the blown resistor is not allowing the contactors to work, isolating your battery. I can't find any information on a KWA 30040 resistor. If you can get ahold of the smart's electrical schematic, you can see what resistor they call for. On the Leaf Ww were able to find a whole "battery junction box" from a disassembled traction battery. Nissan wanted over $900 for the whole unit. They had revised the unit at least five times so we didn't think a new unit would be compatible so we put in a used one that was an exact replacement and that did the trick.
There should be someone with a disassembled smart battery that has a junction box they don't need. Otherwise you could swap in a replacement resistor, if you can get the specifications for it. The Nissan Leaf takes a 40w 30 Ohm resistor for reference.
There should be someone with a disassembled smart battery that has a junction box they don't need. Otherwise you could swap in a replacement resistor, if you can get the specifications for it. The Nissan Leaf takes a 40w 30 Ohm resistor for reference.
Will this PDF file help? https://www.vtm.co.uk/PDF/Vitrohm/Short form Vitrohm.pdf
So according to this data sheet (HERE) the one I took out has the exact same dimensions as the 30W resistor. I checked and it appears digikey only has the 40W version(HERE), which should work, but i would have to move the mounting hole by ~8mm to make it fit in place. I'm going to keep searching.
dimensions are 19mm W, 19mm H, 75mmL, ~38mm from end to mounting hole
dimensions are 19mm W, 19mm H, 75mmL, ~38mm from end to mounting hole
I went ahead and ordered that one, it appears to be the closest one readily available. It was $11.46 shipped, that definitely beats the 38k Mercedes wanted to replace the full pack.
Joined
·
14 Posts
Again, I think you nailed it, looks like the exact replacement. Well done
So unfortunately replacing this resistor did not fix the issue. I'm receiving the same precharge code, and I suspect the resistor I replaced has blown again. My understanding is that in this case there will be an abnormal power draw from a component in the HV circuit on precharge which is causing the failure. I've already removed and visually inspected the charger and PTC heater and I couldn't see any damaged components on the boards. I have access to WIS but I have very little experience with it and I haven't been able to find a troubleshooting procedure for precharge issues. If anyone has any ideas, I'm all ears, I only attempted to turn the car on 3 times and clear the codes(precharge taking too long) code is still active, so there is a possibility the precharge resistor hasn't blown yet. Regardless, I'm fairly certain the issue lies in a different HV system that isn't throwing a code.
Do you know the expected resistance values for each system and the system as a whole?
Joined
·
323 Posts
Not really but to be honest, if you charge it with for example 12V the capacitors should be fully charged after a few seconds. Means there is for sure some short in on of the systems. This should be detected very fast.
Maybe we also do a wrong thinking. Means maybe the second contactor is not closing and the fully load is handled by the precharge contactor. This for sure could overload the resistor.
Maybe we also do a wrong thinking. Means maybe the second contactor is not closing and the fully load is handled by the precharge contactor. This for sure could overload the resistor.
Joined
·
14 Posts
I wish I could be more help, I haven't seen any information on the smart EV system. Codes would help zero in on the problem. Did you get a chance to see if the original resistor was OK?
There are no additional codes, so the issue is not generating a code. I didn't have a chance to check the resistor again, but i'm keeping my fingers crossed. I did what @Jmk2020 suggested and tested each HV component individually. I discovered that the AC compressor likely has a bad capacitor (resistance reads very high initially and then near infinite.) I'm currently dissassembling the compressor. I'm attempted to repair it without draining the AC system, so hopefully this works out.
While attempting to disassemble the compressor, I managed to damage one of the circuit boards while trying to remove it, or it may have already been damaged, either way I'm going to buy a replacement compressor. I found one from CA for cheap, hopefully it's still available. I also went ahead and ordered 3 more pre-charge resistors so I have a few spares incase I have to do this a third or forth time.
Joined
·
323 Posts
You wrote about high resistance. Did you mean high current means low resistsnce? Because if there is high resistance it will not load the hv line. Only if the resistsnce is very low there could be a short of the capacitors.
By measuring on the connector from hv battery connector to hv line with all ecus attached, you easy could disconnect unit for unit till you see a resistance jump or if you work with a dc supply current jumpt to become less current.
By measuring on the connector from hv battery connector to hv line with all ecus attached, you easy could disconnect unit for unit till you see a resistance jump or if you work with a dc supply current jumpt to become less current.
41 - 55 of 55 Posts
