lost... just lost...

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Donn224197

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so i'm trying to figure out my issue here and maybe someone can shed some light on this cause i'm sick as hell of it...
:emotions122:

so about 5 months ago now i replaced my rear axle as a whole (long story involving a broken upper control arm and a 300 mile drive to get home that had to me made) and didn't replace the speed sensor on the top of the diff (i've been told it dictates speed output and engine idle). i've never had an issue with it cutting out til after i did a little 2 tracking after my axle swap. after i got out of the mud and rain i didn't have any speedo input. never the less having needed to get home i had to drive without it, within 5 or so miles it came back and didn't have an issue for a while..
now!!!! within the last month or so it's been randomly cutting in and out. it'll startout working then cut off. if i go for some time it'll come back on sooner or later and then be fine til i stop for a while again. i don't know if time or temp have anything to do with it as it seems too random to be that.
thinking it was my wiring to the sensor on the diff (thumbing through the pages here it seems to be rather common to have the wires open or short out due to rubbing and bending) so i crawled under and rewired from the grommet to a new connector i bought from my local jeep dealer. NOW IT DOESN'T WORK AT ALL. i try not to be a parts changer but just for good measure i installed a new speed sensor as well but that hasn't helped either.

IN THE NAME OF ALL THAT IS HOLY HELP ME!!!
i'm running low in ideas as to what it could be aside from i blew out an input on my ECU or whatever the sensor leads run to. i haven't looked up the schematics just yet.
if you feel i left anything out or have an idea please please help.
thanks
Donn
 

Donn224197

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Could the problem come from the sensor you didn't replaced? I would try that ;)

in theory that is an idea and one i'm going to test tomorrow, it's just the only unfinished part from the sensor back that i've not replace is the lead wires running from the grommet leading out from the cab to whatever control unit they go to. (again i'm unsure where they end cause 1 i don't have ABS and 2 i have a manual)
as well, it worked before hand. just random cutout. nothing moves or has been moved from the grommet forward when it comes to this circuit.
 

Donn224197

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okay okay! another fast question among this topic!
be it that this sensor was a two wire i just automatically thought it to be an AC type, meaning the polarity of the wires didn't matter. but i noticed that now looking at the diagrams i have it says there is a 12 power and a return per my twisted pair!?!
am i right in guessing then that i could just have my wires backwards? i mean seeing as it's not AC type i would guess that polarity matters now.
 

tjkj2002

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It's a AC signal but the polarity matter in this case.The yellow wire is the 12v wire and the other is the return.I run a AC signal generator to operate my speedo,been working just fine for 3 years.
 

Donn224197

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It's a AC signal but the polarity matter in this case.The yellow wire is the 12v wire and the other is the return.I run a AC signal generator to operate my speedo,been working just fine for 3 years.

i'll run with this idea but it's just so odd to me, why send a dc current if your going to have an AC generating sensor?
:boxed:
 

tjkj2002

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i'll run with this idea but it's just so odd to me, why send a dc current if your going to have an AC generating sensor?
:boxed:



The sensors convert wheel speed into a small digital
signal. The CAB sends 12 volts to the sensors.
The sensor has an internal magneto resistance
bridge that alters the voltage and amperage of the
signal circuit. This voltage and amperage is changed
by magnetic induction when the toothed tone wheel
passes the wheel speed sensor. This digital signal is
sent to the CAB. The CAB measures the voltage and​
amperage of the digital signal for each wheel.

Don't mind the ABS parts mentioned as the rear speed sensor is operated the same way with or without ABS.
 

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