Ok, the problem has returned, vcds indicating an intermittent electrical fault and a sensor problem, together with an awd intermittent signal prob - I will look at that over the w/e as the rear drive doughnut was recently replaced, possibility of said connection being disturbed!

Have had the sensor out and inspected the detector head, all looks fine, with no scuffing etc, I  used some contact cleaner spray on the 2 plug pieces, in the past that solved my problem, this time it didn't, Battery is new, but has been slow charged this week, no change with my problem!

Any suggestions anyone?

Edited 2 September, 20223 yr by Frenchtone

A new one 470 - 490 k

 

I got the sensor out by unscrewing the holding screw, a squirt of penetrating oil, then gentle rocking of the sensor/plug to try to loosen it, then a screwdriver under the flange and gentle upward pressure and, at first it moved a little but eventually it came out easily!

If I have time later today I will check the resistance of the fitted piece and report back!

Edited 2 September, 20223 yr by Frenchtone

Ok reading on OEM sensor is around 11K

I have a slight memory of someone saying that there are sensors with different resistance values, anyone out there confirm or refute that, and anyone got a resistance value for a new OEM piece

Edited 2 September, 20223 yr by Frenchtone

New pieces ordered, will check resistances before fitting, hopefully that will solve my problem!!

Now fitted, resistances 750k , by Bosch, all lights/indicators now out, a minor victory!!

Edited 8 September, 20223 yr by Frenchtone

Hi

 

I don't know what type of sensor is in the Yeti, but if you have a Magnetoresistive type, PicoAuto advise against resistance testing due to a risk of damage:

https://www.picoauto.com/library/automotive-guided-tests/mre-wheel-speed-sensor/

 

A voltage test with a scope on the combined power feed / signal output pin should show a signal of typically 11.0 to 11.25 volts relative to ground as the wheel is rotated, i.e. quite a small swing.

 

Anyone know what sensor type is fitted ?

No  not me!

active wheel speed sensors must never be subjected to resistance tests: this can damage these units, with the only remedy being the acquisition of a new replacement.

 

That is BS, any multimeter is a high impedance test instrument and will not damage an electronic circuit, certainly not one as robust as a vehicle component which has to deal with HT transients and induced voltages.

 

A megger tester might see off an ABS sensor but I would not even be sure of that.

 

 

Always have a good look at the cable running down to the wheel. Flex it about a bit to look for cracks. 

Hi

 

In response to J.R., I must admit that damage from resistance checks with a modern digital ohmmeter did seem rather unlikeley.  Maybe they were thinking of an old analogue Avometer with a 15 volt battery or even a megger.  I guess sooner or later someone will try using one !

 

The reading of hundreds of kilohms puzzled me at first, as it seems much too high for something intended for the automotive world where the leakage from a bit of dirt and damp would be of the same order.  An earlier type inductive sensor would be nearer 1 kilohm.

 

Having read up a bit, it would seem that Magnetoresistive sensors are rather ingeneous, as despite containing an electronic circuit they are able to share their output signal with either the supply or ground wire, so only need two connecting wires.  Normal current through them when working alternates in pulses between 7 and 14 mA, and a sense resistor in the (external) control unit of for example 100 ohms turns this into a 700 mV peak-to-peak voltage signal for conversion by an ADC. Normal voltage drop across the device is about 10 volts.

 

The test voltage of a digital ohmmeter is typically between 1 and 3 volts, which is probably not high enough to make the internal electronics "come alive" even if it had the correct polarity.  The resistance reading is therefore not very meaningful and may vary from meter to meter if they use different test voltages.  However, it's useful in so much that it indicates that there is some internal connection.