Brake issues after towing, then...poof?

NorwegianBlue · 07-01-2023, 03:41 PM

I put my 20' bowrider into the water yesterday, using my 2022 X5 45e as my tow vehicle. It was a short tow -- only about three to five miles and the weight of the boat and trailer is well within its rated capacity.

While I'm backing into the water -- admittedly very slowly because I've only done this a couple of times -- I started to get a series of brake fault messages.

One said something about regenerative braking -- I don't know exactly what, because I was backing down the ramp when it appeared. When I pulled forward, I got a message saying braking assistance is reduced, but it's safe to drive. On the way home, I got a message saying I had a parking brake fault. On my BMW app, I got a message stating "Urgent brakes check up: the brake boost of your vehicle is malfunctioning. Increased pedal forces is requited for braking. Please drive moderately." Oh, and the check engine light came on, too.

Of course this happens on a Friday and I didn't get home until the local service center closed for the weekend.

But the next few times I started the car, the pop-up warning messages started to disappear until it was just the check engine light on. Now that has turned off. You wouldn't have known anything had happened. Poof.

I'm going to call the dealer Monday morning and see what they say, but in the meantime, has this happened to anyone? Any reasonable explanations?

jad03060 · 07-01-2023, 07:44 PM

Do you have the OEM towing package, or an aftermarket hitch?

The 45e uses brake by wire...only during a fault does the pedal directly affect the hydraulic piston, so if that functionality is broken, you won't have brake assist, so it will take more pressure to stop. The OEM towing package comes with upgraded front brakes.

NorwegianBlue · 07-01-2023, 09:01 PM

Quote:

Originally Posted by jad03060

Do you have the OEM towing package, or an aftermarket hitch?

The 45e uses brake by wire...only during a fault does the pedal directly affect the hydraulic piston, so if that functionality is broken, you won't have brake assist, so it will take more pressure to stop. The OEM towing package comes with upgraded front brakes.

Got the towing package.

jad03060 · 07-01-2023, 09:55 PM

What was the weight of the trailer with load? I'd have to look to verify, but if it's more than 1650#, unless the trailer has surge brakes, you need an electronic brake controller, otherwise, you'd be overloading the vehicle's brakes.

NorwegianBlue · 07-01-2023, 09:59 PM

Quote:

Originally Posted by jad03060

What was the weight of the trailer with load? I'd have to look to verify, but if it's more than 1650#, unless the trailer has surge brakes, you need an electronic brake controller, otherwise, you'd be overloading the vehicle's brakes.

It has surge brakes. Total weight is in the neighborhood of 4K.

Di3s3l_Power · 07-01-2023, 10:42 PM

Quote:

Originally Posted by NorwegianBlue

It has surge brakes. Total weight is in the neighborhood of 4K.

I might be wrong but surge brakes don’t work in reverse by design, so all that weight had to be stopped by tow car and might have triggered some overload sensor.
Take it slow while backing in.

Others towing boats should chime in.

NorwegianBlue · 07-08-2023, 11:01 AM

Well, the "poof" part went... poof.

On subsequent drives the check engine light came on, but not every time.

When this first happened, I called the local dealer and made an appointment, but they can't see me until July 12.

Then a couple of days ago, after a 30-mile drive to visit a cousin in very rural upstate New York, I turned the car on after dinner and the dash lit up like a Christmas tree with all the brake warnings again, including a new one saying something about brake booster failure, and a message saying stop, do not drive, call driver's assistance.

At 9pm in rural upstate New York in a restaurant parking lot that wasn't an option.

I drove my cousin home a short distance anyway, very carefully, and could feel the brakes definitely weren't right. When I restarted the car after dropping him off I got a message saying it was safe to drive but to do so moderately.

The brakes definitely were very sketchy -- pressing the brake pedal felt like pressing on a 2'x4' and stopping power was significantly reduced. Made it home with white knuckles, parked the car, and got a rental because the dealer can't see me until next week and I don't trust it.

Anybody else experience brake failure on their car?

jad03060 · 07-08-2023, 03:32 PM

As I mentioned, when the brake system detects a failure, the master cylinder reverts to unpowered brakes...so, it would take a lot more pressure to stop the vehicle. Otherwise, all of your braking is by wire...the pedal just becomes an input to the computer, and the computer decides how to apply the brakes with a combination of regenerative braking. It could be as simple as a loose connector, since it's all electronic. It could be a failed module(s). If you had a BMW OBD II reader, you might be able to narrow it down some, but that's what a warranty is for. Just keep in mind unless you press the brakes very hard, it will not have the same capacity as when it's working properly...you still have brakes, though.

07-01-2023, 03:41 PM	#1
NorwegianBlue Private 29 Rep 60 Posts Drives: 2022 BMW X5 xDrive 45e Join Date: Feb 2022 Location: NoVa iTrader: (0)	Brake issues after towing, then...poof? I put my 20' bowrider into the water yesterday, using my 2022 X5 45e as my tow vehicle. It was a short tow -- only about three to five miles and the weight of the boat and trailer is well within its rated capacity. While I'm backing into the water -- admittedly very slowly because I've only done this a couple of times -- I started to get a series of brake fault messages. One said something about regenerative braking -- I don't know exactly what, because I was backing down the ramp when it appeared. When I pulled forward, I got a message saying braking assistance is reduced, but it's safe to drive. On the way home, I got a message saying I had a parking brake fault. On my BMW app, I got a message stating "Urgent brakes check up: the brake boost of your vehicle is malfunctioning. Increased pedal forces is requited for braking. Please drive moderately." Oh, and the check engine light came on, too. Of course this happens on a Friday and I didn't get home until the local service center closed for the weekend. But the next few times I started the car, the pop-up warning messages started to disappear until it was just the check engine light on. Now that has turned off. You wouldn't have known anything had happened. Poof. I'm going to call the dealer Monday morning and see what they say, but in the meantime, has this happened to anyone? Any reasonable explanations? Last edited by NorwegianBlue; 07-08-2023 at 11:03 AM..
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07-01-2023, 07:44 PM	#2
jad03060 Major General 3190 Rep 6,846 Posts Drives: X5 45e Join Date: Aug 2018 Location: NH iTrader: (0)	Do you have the OEM towing package, or an aftermarket hitch? The 45e uses brake by wire...only during a fault does the pedal directly affect the hydraulic piston, so if that functionality is broken, you won't have brake assist, so it will take more pressure to stop. The OEM towing package comes with upgraded front brakes.
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07-01-2023, 09:55 PM	#4
jad03060 Major General 3190 Rep 6,846 Posts Drives: X5 45e Join Date: Aug 2018 Location: NH iTrader: (0)	What was the weight of the trailer with load? I'd have to look to verify, but if it's more than 1650#, unless the trailer has surge brakes, you need an electronic brake controller, otherwise, you'd be overloading the vehicle's brakes.
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07-08-2023, 11:01 AM	#7
NorwegianBlue Private 29 Rep 60 Posts Drives: 2022 BMW X5 xDrive 45e Join Date: Feb 2022 Location: NoVa iTrader: (0)	Well, the "poof" part went... poof. On subsequent drives the check engine light came on, but not every time. When this first happened, I called the local dealer and made an appointment, but they can't see me until July 12. Then a couple of days ago, after a 30-mile drive to visit a cousin in very rural upstate New York, I turned the car on after dinner and the dash lit up like a Christmas tree with all the brake warnings again, including a new one saying something about brake booster failure, and a message saying stop, do not drive, call driver's assistance. At 9pm in rural upstate New York in a restaurant parking lot that wasn't an option. I drove my cousin home a short distance anyway, very carefully, and could feel the brakes definitely weren't right. When I restarted the car after dropping him off I got a message saying it was safe to drive but to do so moderately. The brakes definitely were very sketchy -- pressing the brake pedal felt like pressing on a 2'x4' and stopping power was significantly reduced. Made it home with white knuckles, parked the car, and got a rental because the dealer can't see me until next week and I don't trust it. Anybody else experience brake failure on their car? Last edited by NorwegianBlue; 07-08-2023 at 12:14 PM..
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07-08-2023, 03:32 PM	#8
jad03060 Major General 3190 Rep 6,846 Posts Drives: X5 45e Join Date: Aug 2018 Location: NH iTrader: (0)	As I mentioned, when the brake system detects a failure, the master cylinder reverts to unpowered brakes...so, it would take a lot more pressure to stop the vehicle. Otherwise, all of your braking is by wire...the pedal just becomes an input to the computer, and the computer decides how to apply the brakes with a combination of regenerative braking. It could be as simple as a loose connector, since it's all electronic. It could be a failed module(s). If you had a BMW OBD II reader, you might be able to narrow it down some, but that's what a warranty is for. Just keep in mind unless you press the brakes very hard, it will not have the same capacity as when it's working properly...you still have brakes, though.
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