I was recently called to a shop on a 2012 BMW X5 with a 3.0 Liter Engine (Figure 1) that needed a new Engine Control Module (ECM) programmed. The shop had determined that the ECM was internally damaged and needed to be replaced. They purchased a new ECM from the dealer because a used one would not work on this vehicle due to the fact that BMW will not allow it. Most manufacturers have a procedure to overwrite the Vehicle Identification number and realign the module with the onboard Vehicle Security System but that is not the case with BMW. Their Engine Control Modules are a “One-Time” marriage and it is required to purchase a new ECM from the dealer only.
When I arrived at the shop, I needed to see for myself how the shop came to the conclusion that the ECM was damaged. This can usually be determined by a visual inspection or by a simple “smell” test for any signs of a burnt circuit board. Just going on an assumption can be VERY costly if you are wrong in your diagnostic process so I needed to make sure the shop was headed in the right direction. It would be a bad situation if I was hired to program a control module and the vehicle ended up with the same results as the old one. I was hired as a salesman to stuff software and a configuration file into the ECM, and though I wear many hats, my “technician” hat was not the one I was wearing today. However, I could always be hired later to diagnose the vehicle if needed. So I did as I was told and kept my fingers crossed.
This is new!
The head technician in the shop did assure me of his findings by letting me see for myself what he had found prior to me starting the programming procedure. He pointed out a pile of damaged components (Figure 2). I was taken back by his findings and the amount of damage involved on this vehicle. This vehicle uses an electric water pump that had failed. It had basically burnt up and took out components in its path of destruction. By taking a closer view of the water pump (Figure 3) you could see the damage the water pump caused to the water pump connector.
The shop simply replaced the water pump and wired a new connector end to the existing harness but the vehicle did not run very well and was setting a few running codes for Injectors and ignition coils. When the technician did further diagnostics he discovered a burnt connector at the ECM (Figure 4) and he had no other choice but to replace the ECM along with a sub harness for the ECM. What a chain reaction of events for a simple water pump replacement job after the owner of the BMW drove the car to the shop complaining about a CEL lamp on, burning smell from the engine compartment and a vehicle that was not running well.
I liked it better in the old days when a water pump was simply driven by a drivebelt. If the water pump went bad you could easily remove it from the engine and overhaul it on the bench by replacing a bearing that usually failed. That operation now is no longer practical and requires a complete replacement with a new or rebuilt water pump. Then there is this new wave of technology where they want to be rid of the engine carrying too much of a load, driving many components so why not an electric water pump that can be controlled by varying speeds of operation or even turned off when not needed. But I always say that there is always a price to pay for new technology until they get it right.
Okay so now I go through the long process of programming the ECM, making sure I maintain a specific charging voltage between 13-14 volts. On most vehicles if your charging voltage is not maintained within the specification the operation will self-abort if the voltage is too low or too high so it is important to use a qualified battery charger that has a programming feature that will maintain the voltage even if a current surge occurs such as a coolant fan coming on while programming. You don’t want to lose the ECM in the process or it will be your responsibility to purchase another ECM if the parts guy is unwilling to cover you on your mistake. Most electrical parts cannot be returned and it becomes a tug of war with the parts guy who will interrogate you to make sure you claim ownership of that part that will end up hanging on your wall as a memory.
Programmed, but not running?
I finally finished my programming task and I go to start the vehicle and it will not start. This seemed odd to me because I had followed through on all the step-by-step procedures without skipping a beat. The technician was even looking over my shoulder as I was doing the job and we looked at one another in disbelief. Then came these words out of his mouth, “The car was running before with the old ECM.” This remark was insinuating that I did not program the ECM properly but I have done many BMW control module installations and was very careful in the process. So now this vehicle had me second guessing myself and I sat there scratching my head as to why the vehicle would no longer run with the new ECM Installed. Now it was time to put on my “technician” hat and remove the “salesman” hat and go to work.
I scanned the entire vehicle to get a complete overview and recorded the codes in each control module. I next cleared the entire vehicle to see what codes would reappear. Keep in mind that during the programming process it is normal for many controllers to set codes when the ECM goes offline while being programmed. When I attempted to start the vehicle it still would not start after a few key cycles and cranking attempts. I proceeded to communicate with the ECM and scan it for any new codes. The good news was that the ECM was alive and well, but it had a few current codes in memory (Figure 5). The ones that caught my attention were codes 2A61 (Relay, Ignition and Injection system, supply voltage, fuel injection: Line disconnection) and 387F (Power management: Standby current violation). Without even having to read documentation on these codes and using my common sense diagnostics these codes were directing me towards power feed issues for the injectors and ignition coils. I now had to look at wiring diagrams to make sense of it all.
By looking over system diagrams I discovered that these injectors and ignition coils were not feed power directly from a fuse but rather through power drivers internal to the ECM. This Engine Control Module had the ability to control both sides of the injectors and ignition coils but the ECM was fed power supply for these drivers from an integrated relay module assembly that housed the ECM main, Injection/Ignition Coil and Valvetronic Relays (Figure 6). This Integrated Relay Module was not located in an easy access area but rather buried deep below the windshield, in the right side cowl under the passenger cabin filters (Figure 7). I’m thinking that this would be a bad location to stick electrical items especially if any water coming down the windshield would breach its normal travel to the base of the windshield and out the drains provided in the cowl.
I located the Integrated Relay Module at the base of the cowl well (Figure 8) but I needed to remove the module from its location to get better access to testing all the wires. By doing this I unfortunately had to unplug all the connectors and move everything up out of the lower cowl. To my surprise I found that the module connections were all corroded from moisture (Figure 9). This was probably due to a prior water leak by the looks of all the leaves at the base of the cowl housing. This poor BMW owner was not having much luck with his car because now he was looking at another part that had to be added to the list and hopefully the harness connectors could be salvaged without replacement.
But wait! There’s more!
When I removed the module from the vehicle and it was in my hand my human sensors kicked in. I smelled something that I was accustomed to that had that sweet smell to it. I took a closer whiff at the module and it smelled like antifreeze and it was not water at all. All of a sudden a light went off in my head and I cracked the case! This vehicle was exposed to “Automotive Intravenous.” Something I have not seen in years! When the water pump burnt the connector the plastic housing was compromised and allowed coolant under pressure to force antifreeze through the engine harness. The antifreeze worked its way back to the ECM which was located under the intake manifold and caused damaged there and then the antifreeze took another journey down into the cowl and trashed the Integrated Relay Module. Wow!! What a turn of events!
I basically sat there for a moment because I was mesmerized by this whole situation. You just never know what you will come across in this automotive field of diagnostics and all you can do is keep an open mind and be alert. Don’t be the one wearing headphones and listening to tunes while working on a car because you will miss out on all the experiences you need to gain using the sensors you were given at birth. My only hope is that this article has opened your mind and hit home with some of you techs out there.
