Possible BCM issue??
#1
09-01-2023, 07:45 AM
Possible BCM issue??
Hello all,
I am currently going through quite an issue with my new to me 06 MCS. I will try to lay out everything as clearly as I can.
I purchased this car a few months ago in Charlotte to serve as my (fun) commuter for work. Previous carfax was fantastic; One owner from purchase to 132k miles. Services performed regularly. Seals replaced, clutch, oil, tires, you name it. Clearly garage kept as well by looking at the paint. Checked all the boxes for me to purchase it. Second owner had it for less than 6k miles and needed a truck, but was reluctant to sell it.
Fast forward about a month or so and I begin to have issues directly related to rainfall. The car would crank endlessly but not start. All interior and exterior electronics would work except one thing; the drivers side (left) tail light. I would notice that if the car would fail to start, the tail light would not work as well as the turn signal indicator. While the key is in accessory, if I pressed the brake, the brake light would come on, but with a rhythmic interruption. Should I turn on the parking lights or the headlights, the brake light would turn off. As soon as the brake light and turn indicator acts normally, the car fires right up. No CEL. I have a new battery, I can safely say that is not the issue.
I suspected it is the BCM giving me issues. The antenna was removed and I cannot speak as to why. It had body tape over the hole. I took it to a european specialist shop close to me (Hendersonville NC) to diagnose what is going on. They did some diagnostics and did find water in the BCM, albeit a drop or two. They dried it out as well as the entire car over a hot weekend, and let me know the antenna hole was the cause of water ingress. They quoted me a new antenna at $1k, to which i declined. They had no issues starting the car 22 times during its stay at the shop. I went to pick it up thinking the issue was resolved, and when they went to pull it around the car would not start. I left it with them for another week for the problem to arise again.
It did not have any issues for that week, so I picked it up and drove home. Fast forward two days later, same issue arises. Cranks, doesn't start, tail light malfunctioning. Called a tow truck. While waiting for the tow, the tail light acted normally and it fired right up. when the tow came, the issue presented itself again. The issue persisted at the shop, thankfully, so they could see it first hand.
Spark was confirmed, but no pressure at the fuel rail. The shop confirmed power at the harness to the fuel pump, insisting that the fuel pump, assembly, and filter needed to be changed and that it was the source of the issue. When asked about the tail light, they say it is completely unrelated. Their quote to change the fuel pump, assembly, and filter was for $2300.
In my opinion, the fuel pump has no issues. It is original and stand to be replaced in due time. To me, the BCM is the issue. I want to send it off to get tested. If that comes back well and good, I can replace the fuel pump myself. Given the indications, it cannot solely be the fuel pump causing this issue.
Does anyone else have thoughts about this?
Thank you in advance.
I am currently going through quite an issue with my new to me 06 MCS. I will try to lay out everything as clearly as I can.
I purchased this car a few months ago in Charlotte to serve as my (fun) commuter for work. Previous carfax was fantastic; One owner from purchase to 132k miles. Services performed regularly. Seals replaced, clutch, oil, tires, you name it. Clearly garage kept as well by looking at the paint. Checked all the boxes for me to purchase it. Second owner had it for less than 6k miles and needed a truck, but was reluctant to sell it.
Fast forward about a month or so and I begin to have issues directly related to rainfall. The car would crank endlessly but not start. All interior and exterior electronics would work except one thing; the drivers side (left) tail light. I would notice that if the car would fail to start, the tail light would not work as well as the turn signal indicator. While the key is in accessory, if I pressed the brake, the brake light would come on, but with a rhythmic interruption. Should I turn on the parking lights or the headlights, the brake light would turn off. As soon as the brake light and turn indicator acts normally, the car fires right up. No CEL. I have a new battery, I can safely say that is not the issue.
I suspected it is the BCM giving me issues. The antenna was removed and I cannot speak as to why. It had body tape over the hole. I took it to a european specialist shop close to me (Hendersonville NC) to diagnose what is going on. They did some diagnostics and did find water in the BCM, albeit a drop or two. They dried it out as well as the entire car over a hot weekend, and let me know the antenna hole was the cause of water ingress. They quoted me a new antenna at $1k, to which i declined. They had no issues starting the car 22 times during its stay at the shop. I went to pick it up thinking the issue was resolved, and when they went to pull it around the car would not start. I left it with them for another week for the problem to arise again.
It did not have any issues for that week, so I picked it up and drove home. Fast forward two days later, same issue arises. Cranks, doesn't start, tail light malfunctioning. Called a tow truck. While waiting for the tow, the tail light acted normally and it fired right up. when the tow came, the issue presented itself again. The issue persisted at the shop, thankfully, so they could see it first hand.
Spark was confirmed, but no pressure at the fuel rail. The shop confirmed power at the harness to the fuel pump, insisting that the fuel pump, assembly, and filter needed to be changed and that it was the source of the issue. When asked about the tail light, they say it is completely unrelated. Their quote to change the fuel pump, assembly, and filter was for $2300.
In my opinion, the fuel pump has no issues. It is original and stand to be replaced in due time. To me, the BCM is the issue. I want to send it off to get tested. If that comes back well and good, I can replace the fuel pump myself. Given the indications, it cannot solely be the fuel pump causing this issue.
Does anyone else have thoughts about this?
Thank you in advance.
#2
09-01-2023, 10:28 AM
Electrical gremlins can be frustrating to track down.
It's certainly possible the fuel pump is bad given the age and mileage of your car. But, the coincidence of the lights acting up points to other possibilities.
Two things I would start with:
1. Do a full vehicle scan with a BMW/MINI specific scan tool. It's possible there's error codes that could point you to the root cause (CAN bus communication errors is my guess) without triggering the CEL.
2. The next time it won't start confirm there is/isn't voltage at the fuel pump. It's easy enough to access and all you need is a cheap multimeter.
It's certainly possible the fuel pump is bad given the age and mileage of your car. But, the coincidence of the lights acting up points to other possibilities.
Two things I would start with:
1. Do a full vehicle scan with a BMW/MINI specific scan tool. It's possible there's error codes that could point you to the root cause (CAN bus communication errors is my guess) without triggering the CEL.
2. The next time it won't start confirm there is/isn't voltage at the fuel pump. It's easy enough to access and all you need is a cheap multimeter.
The following users liked this post:
noquartr (09-01-2023)
#3
09-01-2023, 12:12 PM
Electrical gremlins can be frustrating to track down.
It's certainly possible the fuel pump is bad given the age and mileage of your car. But, the coincidence of the lights acting up points to other possibilities.
Two things I would start with:
1. Do a full vehicle scan with a BMW/MINI specific scan tool. It's possible there's error codes that could point you to the root cause (CAN bus communication errors is my guess) without triggering the CEL.
2. The next time it won't start confirm there is/isn't voltage at the fuel pump. It's easy enough to access and all you need is a cheap multimeter.
It's certainly possible the fuel pump is bad given the age and mileage of your car. But, the coincidence of the lights acting up points to other possibilities.
Two things I would start with:
1. Do a full vehicle scan with a BMW/MINI specific scan tool. It's possible there's error codes that could point you to the root cause (CAN bus communication errors is my guess) without triggering the CEL.
2. The next time it won't start confirm there is/isn't voltage at the fuel pump. It's easy enough to access and all you need is a cheap multimeter.
I do have a fluke at home, I need to check the pump when the problem arises again.
Its definitely frustrating, but luckily I have another vehicle to use in the meantime. Hopefully I can get this issue resolved quickly and get back to motoring.
The following users liked this post:
ECSTuning (09-01-2023)
#4
09-05-2023, 08:03 AM
Got an update for anyone reading!
Apparently there was a loose ground near the left rear of the car. The ground didn't even have a nut on it! Squared that away with a new nut and all the issues have not presented themselves again. I do plan on replacing the fuel pump and assembly at some point, but it works great as of now.
Apparently there was a loose ground near the left rear of the car. The ground didn't even have a nut on it! Squared that away with a new nut and all the issues have not presented themselves again. I do plan on replacing the fuel pump and assembly at some point, but it works great as of now.
#6
09-12-2023, 10:39 AM
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