EME assembly

[RP67]

I'm in the progress to assemble the EME on a project car I have. I found some perished insulation on cables what I'm going to repair. Just out of curious anyone seen this kind of "corrosion" perhaps anyone knows what caused it? Also I'm not so sure what these connectors/cable for, but I'm sure the insulation is there for the reason...
The connectors part of the A/C and PTC heater connection.
What I'd like to know, what are these connectors, and what issue they could cause?

 

[alohart]

I would guess rodents, but these cables appear to be inside the sealed EME. Was the EME left open without its cover where rodents might have eaten the insulation?

 

[RP67]

No wasn't open for that long. Also the wire in the cables is tin coated, under the un-damaged insulation. As you can see on the picture the wire itself is dark, not shiny. It looks like overheated... not sure whether it's possible or not.

 

[mojo]

In the last of your photos you can clearly see cracking in the insulation, both along and across the wire. Overheating of the wire could be a possible cause, but I guess it's also true that the manufacturer may have (inadvertently) bought a bad batch of cable - I have seen Far Eastern made cables which have extremely unstable plastics used for the insulation, and they can fail in that way (and in other ways, such as degrading to a sticky mess).

Sorry, but I don't recognise the type of connector.

 

[RP67]

Yes, that was my thought as well, luckily the rest of the cables are fine, they seem to be "silicon" cables with a very soft and flexible insulation. I wonder what these cable do.

 

[Neil]

I would add couple of things.
1. Already noted crappy quality cable insulation which would amplify the other possibilities on this list
2. Insufficiently specified cables for the design.
3. Temperature due to environment or high current in cables.
4. Partial discharge damage of the insulation over time due to exposure of high voltages.

I also noticed the dark area on the PCB area possibly indicating heat exposure damage. The string of resistors is possible evidence of high voltage circuitry or power sharing due to higher currents. Of course, it could be due to a heat source beneath this PCB.

Not sure what's being indicated in the connectors.

 

[RP67]

Good spotting with the PCB. I hope that is the part which allows the AC charging. That is the initial fault of the car, what I try to ignore. I can live with DC charging only, and according to the garage who tried to fix it, it will not throw any fault code as it is. Just found another pair of the same cable, at the top of the unit quite far from these two pair of cable. I'm tending to leaning towards the substandard component...

 

[RP67]

Just an update, I assembled the car, and it drives and charges on DC. Tried to read fault codes, they are inconclusive. Trouble shooting procedure in ISTA listing up several component to replace from the "wall charger" to the EME. I'm leaning towards the EME (at least the charger board). ISTA test shows AC (green) in to the EME but no DC (yellow) out...
View attachment 20240924_114346.mp4

 

[Gonville]

From everything on the groups in the UK that would seem to be the EME inverter failure. There is some suggestion that it is a fuse in that sub assembly and some folks think replacing that would if they could result in a great deal less expensive solution to this somewhat common problem. Be interested to see how it goes from here.

 

[RP67]

I think the fuse is in the heating circuit, so I would be surprised if it would have any effect to AC charging. Second hand EME is coming, so I'll start to make some progress on the replacement. The problem is, the car is perfectly usable as it is... except home charging, which would be the best way to live with a small battery.

 

[13bi3]

Just in case you haven't figured out what the black wires are for.. It's the safety interlock circuit.

From bmw:

12.1. High voltage interlock loop The high-voltage interlock loop is used to protect individuals when working on or at the high-voltage components. Via the high-voltage interlock loop it is identified whether one or several high-voltage plug connections have been disconnected. If a high-voltage plug connection has been disconnected, the entire high-voltage system is shut down automatically. A square wave signal with alternating current direction is sent through the line of the high-voltage interlock loop by the battery management electronics SME. The SME and the electrical machine electronics EME evaluate this signal. The line of the high-voltage interlock loop runs through each connector/plug of the high-voltage components, which are able to generate high voltage.

 

[RP67]

... yeah, I've got it now thanks. I should have mention that in the "update" post.