Welcome to Tech Talk, where our resident BMW tech Nick Owen answers all your pressing BMW technical questions, frustrations, and issues. Have a question for Nick? Email him at techtalk@roundel.org. Let’s get into it.
Solving the Three Amigos
My 2001 530i’s (E39 manual transmission, M package, 184,000 miles) yellow DSC light came on after a Club dinner back in May. In late August, I took it out for a spin, and the light magically cleared itself. On my way home that day, the yellow DSC light came back on, along with its two buddies: the yellow brake and ABS dashboard lights. The proverbial Three Amigos!
Do you have a good way to diagnose what component in the system is causing this (rather than just firing the Parts Cannon at it)? And if it is the ABS controller, do you recommend new more than having it rebuilt? I have seen the videos from home mechanics who have had theirs rebuilt, and I have seen the eBay places pitching those services. The skeptic in me is not sure that they do more than just closing the circuit that turns on the light before mailing it back to you.
Thanks for any insights.
Dave Oldham
Raleigh, NC
The first step here is do a fault scan to see what exactly the faults are. We need to establish if we have a control unit problem or a sensor of the affected control unit in question. Assuming we have a failed control unit, ABS/DSC to be specific, you are going to have to decide. New or used? When it comes to replacement parts, I would advise that a new part is more probable to work and for a longer period than one that is rebuilt or used. Granted, there may be good rebuilds out there, but there are probably some quick fixed ones that will not last as long. But if you can score a used one for cheap, then that is not a bad deal either. What is it worth to you? My motto has been you get what you pay for.
Nick,
Here is a quick postmortem for you.
Instead of paying the diagnosis fee at my local independent shop, I rolled the dice on a new, upgraded code reader. My old one did not show any codes despite the three illuminated yellow lights on my dashboard. The new reader gave me two codes that pointed to DSC precharging pump and return pump faults. When I put the two codes and my symptoms into Grok, it gave me “a greater than 90 percent chance that the problem stemmed from DSC/ABS controller.” I had read that if you have the existing controller repaired or rebuilt there was no need to have it recoded to car, which would be required if you buy a new one.
It was super easy to access and remove, so I sent it to a shop in Idaho (Module Master) that specializes in rebuilding these and other automotive electronics. It came back inside of 10 days with a five-year warranty. After popping it back in and resetting the codes, I took it on a 500-mile test drive to the BMW M School in Greer, SC (as always, a great time!). Unfortunately, on the ride home after the school, I actually had to engage the brakes hard at highway speed. The good news is that they worked perfectly.
So all in, this was a sub-$500 repair (including the cost of a fancy new code reader) for a 25-year old car, and the new part has a five-year warranty to boot.
Dave Oldham
Confused Lights
My car is a 2012 3 series convertible (WBADX7C57CE745328). When started after sitting for a few hours, the headlights as well as dash lights flash for several seconds. This happens when they are set in the automatic position. When operated in manual mode it does not happen. It does not happen on restarts throughout the rest of the day. The car does not show any faults.
The dealer replaced the footwell module, which did not solve it. Both the dealer and an independent BMW shop are at a loss. One tech guy I spoke to thought maybe a battery/starter issue. The battery is only a year old.
Your thoughts?
Thanks,
John Gierasch
Delray Beach, FL
Based off what you are describing, if this only occurs when the headlight switch is set to the “auto” position then I would look at the rain/light sensor in the windshield. That sensor is what tells the FRM if its night or day to automatically turn on the headlights.
Hope this helps, let me know what you find.
HVAC Stank
I am the original owner of a 2019 X3 M40i and absolutely LOVE my vehicle. About a year or so ago, I noticed a strange odor coming from the AC unit. The odor would almost remind you of a vinegar or egg type smell. It is much worse when running the AC on cold. It does not seem to matter if I have outside air or recirculate on. When I use the heat function, it is much less noticeable.
I took the vehicle to my local BMW center and they “Deep Cleaned” the AC components which helped for a little while. Sadly, after several months, the odor is starting to come back. I thought it was just me, but my family noticed it when they were riding in the vehicle with me.
The dealership said that if the odor returns, they would have to replace some of the components like the condenser, evaporator, etc. and that it would be major surgery.
Have you ever heard of this before? Do you have any advice that I can share with the dealership or are you aware of any Technical Service Bulletins that might relate to this?
Again, thanks for all you do and if you have any questions, please let me know.
Patrick Dougherty
I am familiar with this complaint. The smell is mildew buildup inside the heater box behind the dash. Inside the heater box holds both the A/C evaporator and the heater core. Generally, what happens is that moisture accrues in the heater box and mildew starts to build up, causing the smell. This is mainly attributed to the evaporator as it is constantly, slightly wet (or dripping) when in use depending on the humidity levels of where you reside.
If the dealership did a “deep clean” they probably replaced the cabin filter and did a “smoke bomb” which is an effective cleaner, we use to help with interior smells. But the real way to fix the issue is to remove the heater box and replace the evaporator. I suppose you could use some diligence to clean the heater box in hopes of getting any other sources of mildew but replacing the heater box is the only way to ensure the smell is removed.
I think your best bet right now is to do a smoke bomb every six months. Chalk it up as another maintenance item but it is probably the most efficient way of dealing with the smell now.
