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ABS issue


January 15, 2012
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City, State
Canada EH!
Year, Model & Trim Level
1999 Explorer Sport
We got my girl friend a 1999 Sport cause she liked mine. We picked it up with an ABS light on (hoping it was just a wheel speed sensor or something). Scanned the codes and found quite a few...
-C1244 left front speed sensor input circuit malfunction
-C1233 wheel speed left front imput signal missing
-C1145 right front speed sensor input circuit malfunction
-C1234 wheel speed right front input signal missing
-C1230 wheel speed sensor rear center input circuit malfunction
-C1102 accelerator switch circuit malfunction

I figured with this many codes present it had to be either the control module or not getting power or ground. Checked all the fuses I could find and all are still good. Swapped the ABS control module out of my truck to hers and still has all the codes. Anyone seen problems like this before? Does the harness break somewhere or something? Any ideas would be appreciated.

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Sometimes these codes can be confusing. Especially when a lot
pop up like this. The most common failure on these models seems
to be the speed sensor located on the drivers side front of the
differential. It's very easy to change, one small bolt, and it's
inexpensive. I'd start there...

The C1230 indicates this sensor may not be sending a

There are 3 fuses supplying power to the ABS module. If you're getting codes for all of the wheel sensors, and you've tried a different controller than I would look at 1 of these fuses being blown, or a bad ground. In the battery junction box there are 2. There is a 30a mini fuse(fuse 7) for the ABS controller CPU itself, and a 50a maxi fuse(fuse 3) for the ABS pump. There is also a 10a mini fuse in the fuse panel inside the car that supplies the ignition input voltage.(fuse 14) The ABS controller connector pin numbers are as follows: CPU+12v, pin #25 ; pump+12v, pin #9 ; ign+12v, pin #20 ; and ground is pin #8 and pin #24 .

Here is the connector pin out.


perfect. i was looking for a pinout. this should help a bit.

Also dirt and brake dust will cover the sensors on each wheel.

Also dirt and brake dust will cover the sensors on each wheel.

Yeah I have inspected each sensor already. Made sure tone wheels weren't missing teeth and everything is free of debris.

Going to check powers next time I have a chance.