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From: Steve W. on 28 May 2010 22:36
stryped wrote:
>>
>> - Show quoted text -
>
> Can I check the wheel speed sensors with an ohmeter?

They are not that easy to test. They are basically modified hall effect
sensors and generate a frequency that the ECU calculates into a speed.

The easy way to test them is with a scan tool. You can drive down the
road and see what speed and frequency the ECM is getting from each sensor.

--
Steve W.
(\___/)
(='.'=)
(")_(")
From: aarcuda69062 on 29 May 2010 03:22
In article <htpuj5$a2q$1(a)speranza.aioe.org>,
"Steve W." <csr684(a)NOTyahoo.com> wrote:

> stryped wrote:
> >>
> >> - Show quoted text -
> >
> > Can I check the wheel speed sensors with an ohmeter?
>
> They are not that easy to test. They are basically modified hall effect
> sensors

No they're not, they are permanent magnet generators. Very basic.

> and generate a frequency that the ECU calculates into a speed.

The EBCM uses both frequency and signal amplitude.

> The easy way to test them is with a scan tool. You can drive down the
> road and see what speed and frequency the ECM is getting from each sensor.
From: Steve W. on 29 May 2010 09:52
aarcuda69062 wrote:
> In article <htpuj5$a2q$1(a)speranza.aioe.org>,
> "Steve W." <csr684(a)NOTyahoo.com> wrote:
>
>> stryped wrote:
>>>> - Show quoted text -
>>> Can I check the wheel speed sensors with an ohmeter?
>> They are not that easy to test. They are basically modified hall effect
>> sensors
>
> No they're not, they are permanent magnet generators. Very basic.

And the interruption of the magnetic field through the inductance coil
by the reluctor which generates the A/C waveform is called? The Hall Effect.

Either way a resistor can't be used to test them. And an ohm meter is
useless unless you want to see if they are open. The best method is with
a scope and watch the waveform coming off the sensor wile in motion. BUT
I'm kind of doubting he has this available. OR knows how to use the info.

>
>> and generate a frequency that the ECU calculates into a speed.
>
> The EBCM uses both frequency and signal amplitude.

True but ABS function is controlled through the 150K signal on a KH system.

>
>> The easy way to test them is with a scan tool. You can drive down the
>> road and see what speed and frequency the ECM is getting from each sensor.


--
Steve W.
(\___/)
(='.'=)
(")_(")
From: Mark Olson on 29 May 2010 10:14
Steve W. wrote:
> aarcuda69062 wrote:
>> In article <htpuj5$a2q$1(a)speranza.aioe.org>,
>> "Steve W." <csr684(a)NOTyahoo.com> wrote:
>>
>>> stryped wrote:
>>>>> - Show quoted text -
>>>> Can I check the wheel speed sensors with an ohmeter?
>>> They are not that easy to test. They are basically modified hall effect
>>> sensors
>> No they're not, they are permanent magnet generators. Very basic.
>
> And the interruption of the magnetic field through the inductance coil
> by the reluctor which generates the A/C waveform is called? The Hall Effect.

No, you _are_ wrong, that is NOT the Hall effect.

Wikipedia's page is actually quite good and has it right.

http://en.wikipedia.org/wiki/Hall_effect

From: aarcuda69062 on 29 May 2010 10:39
In article <htr673$vft$1(a)speranza.aioe.org>,
"Steve W." <csr684(a)NOTyahoo.com> wrote:

> aarcuda69062 wrote:
> > In article <htpuj5$a2q$1(a)speranza.aioe.org>,
> > "Steve W." <csr684(a)NOTyahoo.com> wrote:
> >
> >> stryped wrote:
> >>>> - Show quoted text -
> >>> Can I check the wheel speed sensors with an ohmeter?
> >> They are not that easy to test. They are basically modified hall effect
> >> sensors
> >
> > No they're not, they are permanent magnet generators. Very basic.
>
> And the interruption of the magnetic field through the inductance coil
> by the reluctor which generates the A/C waveform is called? The Hall Effect.

Actually, it's called 'reluctance.'

> Either way a resistor can't be used to test them. And an ohm meter is
> useless unless you want to see if they are open.

He's got two codes indicating open circuits so an ohm meter isn't
useless and I bet his ohm meter is also an AC volt meter which would
give him some direction on the 'signal missing' code.

> The best method is with
> a scope and watch the waveform coming off the sensor wile in motion.

He can also get direction with an AC volt meter.
We both know that millions of these systems were fixed over 20 years ago
with a DVOM, no scan data, long before lab scopes came into vogue.

> BUT
> I'm kind of doubting he has this available. OR knows how to use the info.

Yup!


>
> >
> >> and generate a frequency that the ECU calculates into a speed.
> >
> > The EBCM uses both frequency and signal amplitude.
>
> True but ABS function is controlled through the 150K signal on a KH system.
>
> >
> >> The easy way to test them is with a scan tool. You can drive down the
> >> road and see what speed and frequency the ECM is getting from each sensor.
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