Can I verify ABS speed sensor by measuring the resistances?

Question

(Newbie got confused in this app.)
Thank you very much. (I will continue updating for others reference.)
There are other codes coming up after my 1st question asked. (details in latter part of this message.)
What I did:
1. I changed both upstream (AF ratio) n downstream (O2) sensors.
2. Change a new battery.
After restarted, yes, P0138 is off for now. will drive road test 50 miles plus to see if it's completely resolved.

I opened all 4 ABS speed sensors (before installing new battery .
Tried to measure resistances of them and checked if I can see voltage outputs, but got confused.
(question: can a speed sensor be verified still good or bad by measuring sensor itself on wheel? )
Below are my readings:
(more explanations followed at %%)
Left Front: (Meter setting) Right Front:
O.L -- O.L (Continuity) 200 Ohm -- O.L
O.L. -- 1947Ohm (2K) O.L --- 1954 ** Ohm
O.L -- 761 Ohm (20K) O.L --- 785 Ohm

Rear Left: (Meter setting) Rear Right:
-- -- lost reading-- (continuity) --- lost reading --- - --- -
O.L -- 1943 Ohm (2K) 561 Ohm -- 1945 Ohm
7510 Ohm -- O.L (20K) 2650 Ohm -- 14370 Ohm.

** stands for highest reading which only appeared shortly, less than 1 second then turn to O.L.
%%
I switched electric test probes (+/-) to get different readings out of curiosity. at each setting.
Q1: Anyone may know why polarity make reading different?
Q2: Can above readings mean they are all bad?

I was not able to get any voltage out put after turning the front rotors.

Plan to order all 4 sensors to replace. But before that,
Please advise will a bad ABS control module causing sensors go bad, or vise versus?
How to determine if my ABS control module is bad ?

I also Got a new code: U0100 ;?
A code says Electric Motor Power Steering code problem.
These seems not showing after reset/clear codes. ?
Again, thank you for your help.

Answer 1

You can't use an ohmmeter to check the sensors, you have to use an oscilloscope

Please advise will a bad ABS control module causing sensors go bad, or vise versus?
How to determine if my ABS control module is bad ?

If you have a bad ABS Control Module you won't be able to get the sensors codes or access the ABS Control Module at all.

Comments

Thank you very mush.
Good to know my ABS control module still good.
Could you clarify:
 Is a good speed sensor supposed having a constant resistance between the two pins in connector?

I'd better start a new question for the codes I got. (U0100 C1201 C1241 C1405 C1406 C1407  C1408)