Intermittent ABS Light and odd speedometer behavior question

[Scott Evil]

Hello Everyone...

We have had our 2007 Mazda5 for 10 months (second owner) and it has been a great family car. It has done 60,000 miles to date and as winter arrived over the past week a couple odd things started to happen. After my first drive in the snow and stopping with the ABS brakes doing a fine job, the ABS light came on and stayed on--my next use of the brakes on a slippy street caused noticeable lock-up. The next day, the light was off and the ABS worked just fine, again on slippy streets.

Then this morning, the light was off and the ABS worked fine as I took my son to pre-school. I hopped back in the car to go to work and as I accelerated away from the school, the speedo read 21 mph with no change, but the car was accelerating. The needle then immediately jumped to 40 mph. There was no noticeable brake drag or wheel spin. Then the ABS light came on without touching the brakes.

The only thing I can confirm is that ABS light off = working ABS, ABS light on = no ABS, but brakes work fine otherwise. I assume the system uses wheel speed sensors, is it possible the speedometer uses the same sensors? I have scheduled service, but have the time to troubleshoot it myself over the next week if possible. The ABS pump works fine when noted above, so I doubt that is the problem (and I assume the costliest part of the system).

Thanks--sorry for my first post being a question. Happy Holidays

 

[the_saint]

First off; awesome username! Second off; zzzzzip it!

As for your ABS issue, I wonder if there is snow/ice packed into the ABS exciter ring and if that would cause the issues that you are having? Can you park the 5 in a garage with a space heater or something? Something that will raise the temp in the garage to get everything thawed out?

Are you getting a check engine light or a check transmission light?

 

[Scott Evil]

Thanks--love the movies and the nickname has stuck.

The car is garaged nightly and it is 40F degrees or more inside the garage. Probably good enough to melt any snow. There are no other warning lights on after start up. It runs fine in fact.

 

[Davicho]

Have your charging system checked. Battery and alternator. It could be the culprit and its a quick and free (most everywhere) procedure. Erratic cluster behavior and warning lights is one of the signs of a bad battery or alternator or both.

 

[rsvinylgraphics]

Could be a dirty or bad ABS sensor

 

[Scott Evil]

Final verdict is a bad ABS sensor wire. The wire had become loose and rubbed on something (wheel or tire) and was shorting out. The codes pulled were C1233, C1155, B1318, B1261.

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