Wisely Automotive Facebook Post from June 14, 2024
This page is a cut & paste from the original Facebook post so that I can reference it for those who don’t have access to Facebook content.
A few weeks ago we were tasked with investigating why a BMW i3 wouldn’t charge at all when plugged into any power source. As promised, here is the full story. 📖👇
The car was recovered to us to conserve what little charge remained. It was confirmed the car wouldn’t charge on multiple 3-pin domestic or 7kW Type 2 AC chargers (no DC charging option fitted).
All HV cables were assessed for damage/rodent bite marks but nothing was found, so we moved to diagnosis using BMW’s workshop system ISTA. Several error codes were showing. We worked through these and determined that multiple error codes indicating an internal fault in the EDME unit were caused by the car being recovered to us with free-wheeling front wheels, so these codes were cleared. It’s important to note, an i3 should always be recovered with all 4 wheels off the ground!
A new ISTA vehicle test presented no relevant error codes. From experience, we suspected the charging cable locking pin actuator was faulty. We could not hear it trying to engage nor could we force it to operate using the test procedure in ISTA. We also know no relevant codes are generated when this component fails making it quite hard to trace if you haven’t seen these symptoms before, therefore we advised the customer this should be replaced.
Unfortunately, the issue remained and no new helpful error codes were generated. The i3 seemingly does not appear to acknowledge that it is refusing to charge.
Our attention moved to a small amount of thermal damage on the L1 pin of the charging port, which could either be the cause or the result of the charging failure. Therefore, and with no other helpful input from ISTA, we advised the customer that we should replace the port as the thermal damage should not be there and that might be why the car does not recognise that a charging attempt is being made. A new charging port (which only comes as part of an entire harness) was fitted, but the fault remained.
Further tests carried out with ISTA confirm the car knows that a charging cable is plugged in but the function state in the LIM for the actuator remains “unlocked” at all times even if the actuator is manually forced into the closed position.
The LIM is a separate “Charging Information Module” which handles the communication during charging sessions between the various high-voltage and low-voltage components involved in the process. ISTA is reporting that there are no faults with the LIM.
With the charging cable inserted, the EME returns a “standby” status which indicates normal operation but the charge readiness remains persistently in “not ready” mode. The EME is unaware that any attempt to charge is being made.
The root cause of the charging failure is now suspected to be either the LIM module (£242 part) or the KLE charger (£1,315 part). The latter was the more logical candidate for replacement as is a known component to fail without logging obvious error codes in ISTA. Also, we found a near-identical case described on an online forum which also featured a burnt-out L1 pin – the poster resolved the issue by replacing the KLE.
Before proceeding, we took advantage of our access to BMW AG Technical Support in Germany by raising a support ticket (sometimes referred to as a TSARA case) with them at a cost of 25 EUR.
After accessing/reviewing all our diagnostics data, BMW’s advice was to replace the LIM and re-assess if necessary. The customer was informed and the decision between us was made to order a new LIM module, unfortunately on back-order with BMW.
A few days later the new LIM module arrived and was plugged in, but the car still wouldn’t charge. ISTA requests programming of said module, however with the HV battery now being so discharged the inverter is offering the 12V systems no support and the car is struggling to stay “alive”, therefore a battery voltage regulator is connected providing just enough power for the car to accept coding. Programming is then carried out and, finally, success! The cable locking pin actuates, the charging port LED ring starts flashing blue and the vehicle starts charging!
Once the battery reached 1% SoC and the car would move again we drove it outside to our 7kW charger where it also started charging without issue. After reassembling everything and checking/clearing any remaining codes, the customer was contacted with the good news.
The total cost for this work was £1,494 consisting of the 3 replaced parts and 5.5 hours of labour – like most of our more involved bookings, much more time was spent in reality.
Most diagnosis work is simpler and more clear-cut than this example, but by working through the issue methodically and by having the ability to reach out to BMW AG for advice meant we managed to get it resolved in the end (albeit 3 weeks later). Some reading this may question why 2 parts were replaced seemingly unnecessarily before the eventual solution was found and, while we wish that wasn’t the case, we don’t have the benefit of hindsight so we have to follow logical patterns and use our intuition – often this will save our customers money, on occasion it will mean extra expense. On this car, our first step, which was the replacement of the cable locking actuator, was a logical first step but turned out to be completely unnecessary. This part cost £90. The next replacement was the charging port harness (£427 part cost) and while this may have not cured the issue either, there is a strong possibility that the burnt-out L1 pin on the port is what initially caused the LIM to fail, therefore not replacing this may well have meant the fault reoccurs.
If we had to put a figure to it, we’d guess that less than 2% of parts we have ever replaced did not ultimately result in a fix and in hindsight would be considered “unnecessary”. We’re pretty happy with that and can recall dozens of examples where we DIDN’T replace expensive components which the customer had been advised to replace next by other workshops before coming to us. In the case of this customer, for less than the cost of replacing the KLE (which the internet would have had you believe was at fault), we found the issue and, importantly, the root cause.
Wisely Automotive
i3 Specialists
🗺️ London, SE16
📞 0208 050 7600