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Discussion Starter #1
I replaced the front pads and rotors on my wife's '07 ZX4 SES. About a week later, the traction control and abs lights came on, and of course she has no TC or ABS now.

Some general searching has told me to use a DMM set to AC volts to test the sensor output. Once she's home from work I'll do that. I've also read to check the air gap under the sensor. Does anyone have a picture of where exactly that's done? I have plenty of feeler gauges, but a quick glance at the knuckle didn't make it obvious to me exactly where I can access the bottom of the sensor.

I have a new sensor ready to go if one actually is bad, but I need to get this fixed by this weekend because I'm leaving the country and winter is coming fast.

Thoughts?
 

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.Flat Out.
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if the sensor is anything like 00-04 models it will have one bolt right above the knuckle, just unbolt that and lift up on the wire. after i changed my knuckle my TC and ABS turned off as well, so i unbolted the sensor and blew some air in the hole, re-installed the sensor and the issue was fixed.
 

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Discussion Starter #3
I already pulled both sensors, cleaned their mounting points and surfaces, and reinstalled, it didn't fix the issue.
 

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Discussion Starter #4
I pulled each sensor plug and hooked up my multimeter to the sensor's prongs. When set to AC volts, there was a definite change in reading as we manually spun the tire, so the sensors are sending out some kind of signal.

Can someone confirm that I'll have to pull the brake rotors off to measure the sensor air gap? I have 24 hours to fix this issue before I'm out of the country, and I'd rather not have to have her take it to the dealership.
 

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FOCUS REVOLUTION
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IIRC you can't really check the air gap on these sensors. it's built into the wheels bearsing and spindle. also it should be sending out a signal
 

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Discussion Starter #6
What do you mean by "it should be sending out a signal"? I confirmed that the AC voltage reading of both front wheel speed sensors changed with tire speed. What else can I do?
 

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FOCUS REVOLUTION
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It should be sending a signal to the elm to know what each wheel speed is that's how abs and tv work if it reads fronts are alot fast then rear it apples the brakes to allow better traction did you check the rear sensors
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The issue may not have anything to do with the brake job. Need to find out what the codes are in the ABS module to really diagnose anything. Could be as simple as a broken wire in the wheel sensor wiring harness, if the sensors are working you need to verify that the signal is coming out the other end of the wire.
 

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Discussion Starter #9
Turns out the brake job was a red herring. I took it into the dealer today and they pulled the code for me - RR wheel speed problem. They took off the wheel and drum and found the tone ring was damaged. I paid for the diagnosis ($89) and the tone ring only ($46), they didn't charge me any labor or time. Very pleased to have this working again, just in time for snowy weather.
 

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Odd, not sure how the tone ring would get damaged with a front brake job lol.
Also when I did my rears I bent the rings a bit and banged them back as straight as possible but still visibly not perfect and I don't have any codes....
Atleast it's fixed for yoou now anyway.
 

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Focal Distortion
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If you have a new sensor, run an abs capable scanner through the obd2 port. Should tell you which corner is the culprit. Swap the sensor and check it again.
 

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Odd, not sure how the tone ring would get damaged with a front brake job lol.
Also when I did my rears I bent the rings a bit and banged them back as straight as possible but still visibly not perfect and I don't have any codes....
Atleast it's fixed for yoou now anyway.
maybe, if(when) they checked the rear brakes, they layed(dropped) the drum on the floor with the ring side down...if so, i could see that action messing up the tone ring..(??).
 
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