Hi .I changed out the rear differential ,w used one,on the 01 3.9 6ctl 2wd an had a question on that differential speed sensor.
I had a generic one I threw in since the OEM one was busted ,on 1st run it was going up an down an abs an brake light on..
I cleared abs an reran it an no more ABS but no speedometer now. It's like it's dead .I tested ohms from the ABS module to sensor an no shorts ..The other gauges work ..the ring gear is the same ,going by the vin numbers also .What should I look at next besides doing the tire turn test on the sensor to see if it's sending a signal?
It brakes fine now .I haven't wanted to run it much until I get this ABS speed sensor going...gonna try oem one in it ..an test the relay ,fuse is ok .I've heard of ispeedometer ssues if u change the differential an the ring gear ratio factor differs but by vin it should be ok..
An what else with the replaced differential should I look at .Does the ABS computer readjust?

Thanks

 

Speedo doesn't care about gear ratio. The sensor reads the tone ring on the carrier, so, ratio simply doesn't matter. Sounds to me like a bad sensor......

 

Is the computer as picky on this abs sensor ,not being OEM, as it is with 02 an many other sensors ?
I tested the sensor ohms an it was still in range 1800..the old one was dead - it was in on the 1st run ,after replacing differential ,as GUAGE was jumping around between 0 an 30 at low speed.then it was dead.
I tried the manual tire turn tequnique ,w meter on sensor ,but saw no change in the reading ...I WAS HOPING TO SEE IT CHANGE A DEGREE TO SHOW SENSOR WAS ACTIVE AS TURNING .but it stayed at 0.00..not sure if maybe I needed to spin the tire faster though..you ever tried this test ? .I'll try a oem sensor .. .
Anything else to look at besides this such as power into sensor or relay ,etc?
Thanks
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It's essentially just a hall effect switch... It doesn't generate a voltage, it generates a wave form, and frequency goes up with speed. Just like the crank position sensor....... You wouldn't think the system would be all that picky, considering how it is supposed to work..... and so far as I know, folks have been using aftermarket sensors there without issue on the full size trucks for some time. The biggest problem I have seen though, is too large of a gap between the tone ring, and sensor..... such that it simply won't read reliably.....

To really test the sensor, need an oscilloscope... If you have a fairly high zoot scanner, it should also be able to show you what the sensor is reading...... but, and fault in the system anywhere, and it just sits at zero. Might be a bad sensor, might be a bad wire, or any of a number of other things..... We havin' fun yet?

 

Thanks I'll try a oem sensor.

I don't think those typical ABC code readers monitor it but I may rent that one an see if it has a reading on the sensors ..would be great if the ELM32 had a Abs app .

Maybe I can jumper 2 long wires to the sensor leads from the back of the connector ,an then take it for a ride an see if it shows a change on the digital reading as driving ..would that tell me if the sensor an the tone ring set up in the differential are good?

An since I had a bouncy speedometer earlier on a test run does that show the inside tone ring set up is working correctly?
Having that wire adapter extension,that it doesn't even need , helps when testing

 

Not sure what the digital meter will read from the sensor..... You *might* see voltage...... but, as its a frequency signal, the digital meter may not react fast enough to display anything...... I just don't know.

 

It's Working!!
I stuck a used OEM on it an reset ABS !
Not sure if it just needed another abs reset or it was picky w that off brand sensor....
Now -to see how the differential does ~
Thanks

 

Awesome. Let us know how it goes.

 

I had to readjust the TV cable ,clip had come off...I've also been testing the shifting points an even did a reset on TCM.I only took it on the highway once an not long,sluggish ..on the city roads,not over 50mph, I took it out for some major errands over 100 miles ..It's shifting ok at 1st to 2nd 18mph 1800rpm ,2nd to 3rd 28mph 1900rpm but I'm not feeling a 3rd to 4th even as going up to 55 ..it's in the automatic overdrive that it goes into after starting, an there is a tad less power than my last rear end ..no codes..Is that abs. Diff sensor a culprit or did that switch of the replacement differential factor ?..Is it in a safe mode or limp mode maybe?. .If ratio is off id think I would get a code..I also was wondering if the shift solenoid or the gov could be the issue. What would you look at 1st ?
That last differential was the culprit with that humming noise now gone-likely pinion seal. .I don't think that could have impacted the sensors but it's worth mentioning.
Any info is appreciated.
Thanks

Update..I'm gonna also replace all the shift sensors,filter, some fluid,an gov,transducer,speed sensor ,overdrive sol,,etc w a kit..like I did way BK with the 02 Dakota. ..



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