ABS / ASC bye bye in thick snow... Happen to you?

[Eric]

Since I got it about five years ago, my ti has had the ABS and ASC lights come on (with no ABS or ASC function) four or five times, all after driving in heavy wet snow / slush. All returns to normal after a thaw (usually a few days).

I have assumed that snow is packing around one of the wheel sensors (probably rear), but never tried to find it (who wants to lie in wet snow screwing around under the car?), but the last three times this has happened have all been this year, and even though it's fun fishtailing around spraying slush and doing doughnuts, I'm getting tired of not having ABS and ASC at exactly the times when I most need them.

Anyone had this happen?

Any advice?

Thanks,

- Eric

[roadrash]

When the ASC+T light comes on, that indicates that the system has been activated and is working. (Unless you're referring to a different light.) Are you sure that the ASC is not functioning when the light comes on?

I'm not sure but I'd assume that the ABS system does the same thing.

[Eric]

Sorry, guys. The ASC light is ALWAYS on.

When the ASC light FLASHES on, it means the ASC is working.

When it is on steadily, along with the ABS light, whenever the car is running, it means the system isn't working (and no, the ASC is not working, and neither is the ABS).

I'll check those connectors when I can - couild be salt water got into them, I suppose.

- Eric

ps: the reason the two systems fail together is that the ASC uses the ABS sensor system to determine whether a rear wheel is slipping.

[Hwy1Strat]

I just had the same thing happen to me today. The ABS light and ASC light came on and stayed light (not going out or flashing).

We just got 9" of snow last night and my 1997 318ti was plowed in. I dug it out as best I could. To get it onto the street I still had to drive in snow that was up to the bottom of the car. The lights came on immediately after I got out of the drift. I tried to shut down and restart the car, but No ABS or ASC.

I think that the reason why ACS goes out with the ABS in this case is that both systems use the ABS wheel speed sensors and brakes to do different jobs.

For ABS it's simple, it's controls wheel lock-up under braking.

For ASC, the wheel sensors are used when the brakes aren't applied to sense when one drive wheel is going significantly faster than the other (wheel spin). Since the diff is open (at least on my car) the ABS system then applies brake pulses to the spinning wheel. The mechanical open differential then splits the engine torque to the non-spinning wheel. This is how traction control is done on many cars. It uses the ABS system.

We shall see if my issue also goes away in a couple of days. I suspect that water (from melted snow) has migrated into a connector via a dry rotted seal, shorted the sensor, and tripped the light.

At least I hope it clears in a day or so. ;-)

~Mike R~

[jenkinskg]

I have a 97 318 ti and just the asc light comes on.
ABS always works.
I would say if abs light comes on, bleed brake system
Mine only comes on after some driving , I think it is a sensor issue
Any ideas?

[cooljess76]

^^^+1

On ice or snow, there's really nothing you can do to stop the drive wheel from spinning besides letting off the throttle. When the vehicle senses traction loss ie; wheel slippage(one wheel spinning faster than the other three), it activates ASC which cuts off airflow to the engine and applies braking to the opposite wheels. During this time, you'll see the ASC light flash until traction is regained. You can however, turn ASC off by pressing the button. You'll see the light illuminate and it will remain illuminated until you press the button again. The ABS works the same way, but you can't turn it off. If the vehicle senses skidding, the ABS pump will activate and you'll hear a buzzing sound along with a pulsating feel in the pedal.

Now if your system is remaining on for days, then you probably have an issue. Perhaps you have a cracked/frayed wire, dirty ABS sensors(don't try to remove the fronts, they'll crumble if you do). Another cause of these problems would be if you're running differnt diameter tires. The vehicle will think one wheel is spinning at a different rate as the others(which it would be), and it would trigger ABS and/or ASC. I'd recommend investing in some nice snow tires.

[Mr. Crow]

Originally Posted by cooljess76

^^^+1

(don't try to remove the fronts, they'll crumble if you do)

+1 what a nightmare.


OP, faulty abs sensors are a common fail. These systems(ABS & ASC+T) are built on top of each other, meaning linked somehow. If one fails, so will the other. *i feel like a just quoted the matrix*.

I have had the same issue, its definately a headscratcher. You need a code reader and and new sensors most likely-

good luck!

[zboot]

It is nothing a code reader can find. I had the same problem on my car - from time to time in the snow, the ABS/ASC would go out. A couple days later it would be ok. It was definitely an electrical connection issue - in my case because of bad splicing in of the e30 wheel speed sensors. In your case, your stock connector could be worn or damaged or just not well cleaned. When you get a chance, get under the rear end, check the wires for breaks or frays. If ok, then check the connector housing (The wires are usually have plastic clips to hold them along the trailing arm then there is a larger plastic housing for the ABS and brake wear sensors connectors on the trailing arm as well) - by taking it apart, cleaning it as best you can, then putting it back.

[Eric]

Interestingly, on my car, after the most recent episode (about 2-3 weeks ago), the lights never went out again.

It had snowed, lights had come on, and for a few days, the lights would go off when first starting off in the morning, then come on again after a few miles and stay on until the next day.

One day, they turned off. The roads were dry. I drove around doing errands, and they stayed off. I found a deep puddle in a parking lot, and drove through it fast, to see what would happen. The lights came on about five minutes later (NOT right away).

The next morning they were off again. It was warm (40°F) and dry, so I jacked up the car and checked all of the wheel sensor connector plugs. They all looked clean and dry inside. I put them back together with Vaseline (protects against water and corrosion, doesn't affect continuity).

After that, the lights were on, and haven't gone out since, so, obviously, it's something I did when I manipulated the connectors. (It's not the Vaseline, since that doesn't conduct electricity, and would be pushed out of the way as the connector blades slid against each other in the plug.) My guess is that it is the mud / sand mix compacted onto the tops of the front plugs - if there is enough salt in it, and if some of the salt has gotten onto the bare parts of the wires, it can be leaking current across the leads, which might be enough to confuse the computer.

Next time we get a few days of thaw, I'll try really hosing all of the connectors with fresh water to rinse the dirt and salt out of them (maybe the sensors, too), and see what happens. I'll have to check after I do each one to see whether it fixes it - I didn't do that when I played with them before, so now I don't know which one it was that caused the problem.

If that doesn't work, I guess I'll take out each sensor and look at them and at the reluctors and make sure they are clean and intact. If that doesn't do it, I may just go nuclear, snip out all of the plugs, and solder all of the wires together. If that doesn't do it, I'll probably give up and put neat little pieces of electrical tape over the warning lights, like I did with the airbag light...

- Eric

[Hwy1Strat]

I had to run a errand at lunch, both lights were out. Both the ABS and ACS were working OK again. So in my case the system reset it's self.

I have never had this happen before. So I will keep an eye on it and let everyone know what happens.

BTW, if you have to get ABS wheels speed sensors shop around on-line. I saw the same brand OEM replacement units got for extremely different prices between vendors. The OEM's (with BMW part numbers) are made by ATE (at least for 1997). About $280 for all 4 was the cheapest price I could find.

~Mike R~

[MacUser]

Have you guys considered this option:

MOVE SOMEWHERE WITH LESS SNOW!


Although with recent weather patterns, I'm sure where that would be! After spending three days digging my ti out from my rear garage, I'm ready to move!

[Eric]

Originally Posted by MacUser

MOVE SOMEWHERE WITH LESS SNOW!

Yeah.

Let me know how that's working out for you...

- Eric

[MacUser]

Originally Posted by Eric

Yeah.

Let me know how that's working out for you...

- Eric

So far? Not so good!

[tiFreak]

Vermont's been surprisingly snow-free for the past couple days

[Eric]

So, to wrap this up, I fixed it.

As I had posted, for several years, I had the ABS & ASC lights in my '98 coming on after driving in heavy snow, and staying on a few hours to a few days (of course, with no ABS or ASC function). This winter, they came on and never went off.

I tried hosing down the wheels and the plugs, removing and cleaning the plugs, and protecting them with Vaseline, but nothing worked.

A couple of weeks ago, I finally got a chance, and went around with an ohmmeter pulling the plugs and testing the continuity. I tried to test from the ABS controller (to check the entire length of the wire runs), but I couldn't get it out from its cozy spot behind the glove compartment, so I left it there, rather than risk breaking it.

I had to make little test wires for the meter, because it isn't possible to fit two meter probes into the deep ABS plugs at once. I took 18ga wire, stripped the ends long, and wrapped them into little springs - one end around the test probe, the other just hanging out there, to be connected to the sensor plugs (see photos).

I tried wrapping the sensor ends around a piece of 18ga wire, but that proved to be too tight a fit on the pins, so next I used the test probe ends at a guide for both ends of the wire, which was a bit big, but worked. I think about 16ga would be the right size. With the wire wrapped around the test probes, I took the other end and, carefully, fished each piece down into the ABS plug, fitting it over each of the tiny protruding prongs. I needed to do a little wiggling to get the contact right, but I could in each case. (Wiggle to much one way - no contact. Wiggle too much the other way - the wires touch each other).

When I finally got the contacts right, I found that the Left Front sensor had no continuity (∞ Ohms), the Right Front had 1.080KΩ, and the rears had about 1.008KΩ and 1.006KΩ (as I describe here).
Note that I measured the fronts between the two pins that would be the eyes of a face ( °.° ), not the one that would be the nose, which is just a ground

I tried to remove the bad sensor, but found it had become a permanent part of the spindle - I removed the Allen screw, then put a pair of Vise-Grips on the screw ear, and tried to gently rotate the sensor from side to side in the bore, using lots of top-notch penetrating oil (KROIL). All I did was break off the ear after about five minutes of twisting, leaving the stub of the sensor that was impossible to get a good grip on.

So, I poked around on the interwebs, ordered a new sensor, a new hub nut, and a new hub cover from Pelican ($54 for an OEM ATE sensor), and waited a few days.

When I first got the sensor, I wanted to see whether it fixed the problem with the minimum of work, so I reached behind the tire, disconnected the old sensor and plugged in the new one, then started the car. No change - the same two lights stayed on. I turned it off and started it a couple more times, but that didn't do it.

Today, I got a chance to actually work on the car.
I pulled the wheel, caliper, carrier, rotor, and hub. The inner race stayed on the spindle, as it tends to. I covered it with a rag to keep some of the crap off of it.
With the hub off, you can clearly see the ABS sensor poking straight through from the back side. There was no need to remove the sheet metal shrouds, as they weren't in the way. I tried hitting the end of the sensor with a sledgehammer, which caused it to mushroom and disintegrate. I broke off all the protruding end stuff and tried again, but all I was doing was mushrooming the end. I reached in with a hacksaw blade, and cut right through the body of the sensor, right against the surface of the spindle, inside the gap between the spindle and the inner brake splash guard (didn't take a picture, but you'll know it when you see it). The sensor cut like butter, and the end came right out, leaving the stuck portion inside the spindle hole. I tried knocking this out with a large pin punch, but all that did was to punch right through the other side without moving the sensor, so I grabbed a 3/8" extension and hit it with that, and it popped right out after a couple of good whacks. The inside of the bore was a bit rusty, but not terrible. I hit it with the tiny sanding drum on a Moto-Tool, and it looked nice. I put some Nevr-Seize on the appropriate portion of the new sensor and gently but firmly worked it into the hole, screwed it down (bottomed it by hand first), then cleaned and put everything else together (new hub nut torqued to 214 ft/lbs and staked).

When I started it up, as before, I had both lights. I backed out of the driveway (about 40 feet), drove off, and the lights went off after about 10 more feet, and haven't come back on .

So, with any luck, I've fixed it.

Now, about that airbag light...