SOLVED-Trifecta after drivetrain work???
 

At the beginning of this month (naturally just 4 days before our one large snowstorm of the year), my front driveshaft splines let go. Wife accidentally stabbed the throttle to the floor while holding the brake with it in gear while picking up our mail. I had to tow it the 1/2 mile up our hill from the mailbox, and stuck it in my shop until I had the time to sort it out.

On Friday, I received my new front driveshaft with the 1" longer splines, and installed it. Took the car for a quick test drive friday night after I finished, and it worked great! Problem solved!

Until last night... I took it to the gas station to fill it up so it would be ready for the school run this morning. When I restarted it, the ABS/DSC/brake lights were all illuminated. Driving away from the pump I noticed that the speedo wasn't working. Drove it home 2 miles with no speedo, and hooked up my Peake code reader. No codes, but I cycled it to clear codes anyway. Restarted car and everything was fine again. Tokk it for a 2 mile test drive with no problems.

This morning, its acting up again. Trifecta and no speedo all the way to work (35 miles). Tried spinning the steering lock to lock, and no change.

I had similar problems last fall, and had the ABS computer rebuilt in September to fix it. Could this be related to my driveshaft failure, the repair work I did replacing the driveshaft, or should I be looking for something else?

I really like this car when it's working, but I'm getting tired of working on it.

A failed wheel sensor will give you no ABS and DSC since these system requires pulse from the sensor. Still you should have a code, don't know if the Peake can read codes other then OBD II. I would think that because you have the Trifecta of lights you have code(s), but your code reader can't read the code(s). I would get the X scanned with something a little bit better than a Peake Scanner. I used Carsoft 6.5 and now have BMW Scanner 1.4.

If I had to guess I would say the wheel sensor on the driver side rear (LHD) is bad. Don't bother with those cheap sensors on eBay or Amazon. I replace two wheel sensors so far on the X. Both time, the BMW software was able to identify the correct sensor to replace. Last sensor I brought was from O'Reilley Auto parts. Even though it wasn't an OEM sensor, it fitted the wiring harness perfectly and the sensor worked perfectly.

If your speedo is dead, and the ABS module was already rebuilt, I'd look into one of the rear speed sensors on the hub.
Quoted from BF:
If the speedometer and odometer do not work, the driver's side rear sensor is probably bad. If the speedometer works but the cruise control does not, then the passenger side rear sensor is probably bad.


You can also test the sensors themselves with the diode setting of a multimeter to confirm, but since we ruled out the ABS module (already rebuilt), I'd say one of the rear sensors. Be sure to buy genuine OE sensors from BMW, not aftermarket Chinese ones.


Hope that helps!

Is there anyone near Portland that can scan my car for me? I would gladly pay for the service!!!

Test voltage...

When my alternator was going I would occasionally lose my speedo along with the trifecta lights. You said the car sat for a while, maybe the battery went bad over that time and won't hold a full charge, maybe that caused the alternator to work overtime. It's worth a look as checking the voltage is free and takes just a few minutes with the OBC hack.

Test voltage...

When my alternator was going I would occasionally lose my speedo along with the trifecta lights. You said the car sat for a while, maybe the battery went bad over that time and won't hold a full charge, maybe that caused the alternator to work overtime. It's worth a look as checking the voltage is free and takes just a few minutes with the OBC hack.

The following may help: X5 BMW – ABS & DSC Warning Lights & Inoperative Speedometer & Brake Lights Always On | Bavarian Autosport Blog

The above link indicates that the right rear wheel sensor controls the speedo, but everything else I have read says that if the speedo is out, its the left sensor - which is correct?

Does the cruise control and odometer work?

Cruise was working last night. I didn't check the odometer, but the trip meter is not moving...

I would also take Brandon002's advice and use OBC test 7 for voltage while running, just to rule out a bad alternator.

However if the odometer works and cruise works, you're almost certain its one of the sensors. You could always buy one and guess on which side it is, if it doesnt work on the first side then put the new sensor in the other side and swap the other one over, should be working by then LOL!

I hope the alternator is not bad - just did that about a year ago.

I could be making the payments on a new car for what i have put into parts in this POS over the last year...

My guess is that if 2010 Bavauto blog is wrong they would have corrected the error by now.

OK - just drove it to get a sandwich.

Speedo - not working
Trifecta lights - all on.
odometer - not moving
trip meter - not moving
MPG meter - not working
Tach - working normally
Cruise control - working normally
hill descent control - not working

All other parts of the car appear to be functioning normally.

BMWs are very sensitive to out of spec voltage. A bad battery or alternator can cause what you are experiencing. If battery is old suggest you have it load tested. Many auto parts stores with do that at NC. Suggest you monitor the alternator while driving as suggested.

i will watch the voltage on the way home tonight. What should i be looking for?

look for going under 13 or over 14 while running, it should stay in 13.1 - 13.9 range or so I believe.

If the cruise works its almost definitely a rear sensor though.

Probably LEFT rear?

Yep!!!

What I posted in my first post.

If you can't find someone with BMW specific software to scan the X I would recommend that you go and buy the cable and BMW Scanner 1.4 so that you will have it around to do future diagnostic. BMW Scanner 1.4 is the easiest of all the software available to setup on a laptop or computer running windows XP.

Thanks!

I just ordered one from my local NAPA, and will pick it up on my way home tonight. I'll post back after I have installed it.

Plastic connector may be somewhat brittle so be careful when you remove the old sensor. If you do break the connector, it is available at ECS tuning.

Thanks, where is the plug located?

Just follow the wire from the sensor, it will lead you to the plug. It is located in a plastic housing that just snap close.

Although this video is for a 3 series, the sensor is similar including the junction box for the connector.

https://www.youtube.com/watch?v=MKQ0Lm_jPu4

I think on the rear of the car the plug junction is near the wishbone control arm, don't quote me though. It's held in the wheel carrier with one hex bolt. I recommend spraying the bolt with PB blaster, and the actual sensor itself where it is bolted in. After all these years, she is sure to be stuck on that wheel carrier pretty good, you may need vice grips pulling the old one out.

Done, and done! Thanks everyone with all of the help diagnosing this. Picked up my new sensor on the way home tonight, and installed it as soon as I got home. Problem solved! It took less time to install, than I spent standing at the counter at NAPA waiting for them to find my part. Everything works exactly as it should again. Wonder how long the car will give me until the next repair? I had exactly 2.1 miles between failures this time...

Can you go back to the first post and put Fixed or Solved in the title so that people with a similar problem can find the solution.

Good to hear that you were able to fix the BM Trouble U.

Like that?:thumbup:

:thumbup:

Glad to hear. Good teamwork on this one guys helping him to fix it.

Don't believe everything you read on the Internet.

upallnight, Are you sure it is the left sensor that sends signal to the speedometer?

The Bentley manual also reads that the right rear speed sensor provides vehicle speed recognition.

Yep,
right sensor is for the cruise control
left sensor is for the speedometer.

Don't believe me as ChevDog1 which side he replaced.

My speedo was out, and my cruise control still worked. Replaced the left rear sensor, and the speedo now works.

That being said, the Bently manual is correct in saying that it is deriving a speed signal from the right rear - of course, it it getting a speed signal from all four wheels. But it appears from my experience that the right rear speed signal is used for cruise, while the left rear is used for the speedometer.

As an update - the car made the 35 mile trip to work this morning with no warning lights or other failures - MUCH better than the 2.1 miles I got between the front driveshaft repair and this sensor nonsense. Hopefully I can drive it for at least a few months before working on it again. I'd like to spend some time working on my project truck...

I didn't say I don't believe you, I merely asked if you were sure. If I thought you were wrong I would have said so.

I certainly put more faith in actual experience. Sounds like speedometer is working this morning.

I am aware there are sensors on all four wheels The Bentley manual only references the right rear as reading vehicle speed recognition. Vehicle speed recognition must not mean speedometer. I sent an email to Gordon at Bavauto asking why the Blog says right side when X5 owners fix it by changing the left side. I don't believe everything on the internet but I thought Bavauto would be a reliable source. Oopsi.

RB's post #3 right after my post also stated that if the speedometer didn't work it is probably the left rear wheel sensor.

http://www.xoutpost.com/982081-post3.html

I always read all the posts, sometimes multiple times. I knew my input didn't match up. I thought my references were solid, and, right or wrong. I didn't read any post as being positively sure. If I offended you by asking you if you were sure, I apologize.

I never get offended on these forums, even when a Spirited poster on Bimmerforums kept referring to me as a she.

Sputtering Acceleration; rough idle; now, no start! Please help!

Rats, I thought that your picture was of you. I am so disappointed.

Just got a response from Gordon at Bavauto thanking me for finding the misprint and acknowledging the left rear sensor sends signal to the speedo. Sorry Chevdog1. No intention to mislead or cause confusion.

Bumping an old thread here. I switched out the left and right rear speed sensors over a year ago and have gotten occasional trifecta lights sometimes with the speedo not working and most times with the speedo working. I believe the brand of the sensors was Febi but not certain. Is there an ohms value that defines a properly working sensor? Can I spin the wheel and see variability in the reading on a properly functioning sensor? This may also be a correct indication of another problem I'm having either with a binding caliper, a front diff or a transfer case issue.