Here's a Weird One

[Axe Man]

This happen last night and perhaps someone can provide some insight as to what happen. I have a suspicion but I'm not sure.

Vehicle: 2003 Ford Taurus SE Wagon, DOHC V-6, ABS but without the factory traction control.

We finally got a significant snowfall here last night. At least 10 inches. The street to my residence is a very steep hill. It was plowed but still snow covered. Well the car clawed and spun it's way up the hill at about 2 MPH. I kept a steady pressure on the gas but didn't allow the tires to spin too much. It finally made it up the hill but as I got near the top the ABS trouble light on the dash turned on.

Put the car in the garage. Both front wheel wells completely impacted with snow/ice. My first thought was that perhaps the snow/ice might have pulled or damaged the wiring to a front ABS sensor. Or maybe snow/ice got into a sensor. My OBD-II scanner can't pull ABS codes so I was running blind.

Anyway, decided to clean out the snow/ice from the wheel wells. And did a "brute force" reset of the ABS computer by disconnecting the battery. No good. Started the car and the ABS light stayed on. Tried it again. Left battery disconnected for about 10 minutes. Still no good. Decided to test drive the car. As soon as I moved forward the ABS light went off and the ABS system reset. I tested the ABS on the snow and it worked. And the ABS light did not come back on. Car is fine today too.

Can anyone with knowledge of ABS systems explain what happen? My suspicion is snow/ice got into a front wheel sensor. That might have prevented the ABS system from measuring wheel rotation which would have tripped a trouble code. Sound reasonable or did something else happen?

 

[punisher]

When you spun the front wheels while going up the hill the ABS detected that the speed of your wheel sensors didn't match. Your ABS monitors the wheel sensors continuously. If you get a signifigant mismatch in wheel speeds the ABS sets a sensor/signal mismatch code. I wouldn't worry about it.

 

[Earl Filter]

Agreed.

 

[Axe Man]

Quote:

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When you spun the front wheels while going up the hill the ABS detected that the speed of your wheel sensors didn't match. Your ABS monitors the wheel sensors continuously. If you get a signifigant mismatch in wheel speeds the ABS sets a sensor/signal mismatch code. I wouldn't worry about it.

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OK, sounds logical. I would assume the ABS programming does allow a certain amount of wheel spin or perhaps a time limit before setting a trouble code. The wheel spin wasn't excessive but it did occur for about 40 seconds continuously. Maybe that's why it set a code?

But agreed, I'm not worried. I'm just trying to understand what happen and why.

 

[NYEngineer]

I agree with what everyone said. The light went out as soon as you moved the car forward. The computer saw the normal readings and reset.

 

[Tosh]

After my Acura CL comes off the smog tester dyno, the ABS and TC lights stay on for a few blocks but go right off. Same thing?

 

[Vilan]

That's exactly what's mentioned in our smog tester pamphlet. They say if you have ABS the warning light may be on for a while after the dyno test because the computer was detecting different wheel speeds between front and rear.

 

[Axe Man]

One of the reasons I appreciate this forum is the wealth of knowledge and intelligent responses. Your answers make perfect sense and I'm sure that's exactly what happen. We don't have smog tests on dynos here in NYS so I've never encountered the warning about ABS systems getting confused and then resetting. My extended foray up the hill did cause an extended perceived speed differential front vs rear which I'm sure the ABS didn't like so it set a DTC.

Thanks guys!

 

[Gary Allan]

You've gotta love the information age!

I don't have anything with ABS ..but I'll tuck this one in the back of the memory for later reference.

 

[The_Jeff]

If your taurus is anything like GM ABS the self-diagnostic runs when the car first reaches 4 mph or so. So just idling won't cure anything. You may hear a clunk or rattle when the diag runs.