was there ever an description on here about how to test the abs system on the sierras

ive got a sensor down but dont dont know which one and dont know where to start to test the sensors

aboviously would like this working as its crap roads at the minute and im locking up everywhere lol

thanks

 

not much help, but try a search on here, been loads of discussions on ABS recently, you might just find something useful.
There is nothing conclusive in those discussions that I know, however, there have been a few suggestions of contributions from some in the near future, keep your eyes peeled

 

get a multi meter on the sensors one by one and spin the wheel to see which one is not working

 

i asked this a while ago. Not sure how to do it either. Think stu is doing a essay soon.

 

have you tried testing them with a Multimeter then?

 

nah, only found out how to do it the other day.... i think.

 

what settings on the meter

continuity

do i disconnect the sensor and test it that way

or leave it connected and test it but what setting?

 

You need to set it to read in Mili-amp disconnect the sensor, connect the two electrodes from the multimeter into the the two pins in the multi plug of the sensor (not the ABS loom )

Then rotate wheel (after jacking up car ) as the wheel spins the Check for deflection on multimeter. Check the scale on the meter or switch to one that gives a deflection when the wheel is spun. No deflection = faulty sensor.

*Edit* I wrote Mili-volts instead of Mili-amps

 

right so basically

i need to see if theres a reading on the sensor when i turn the wheel

but surely i wouldnt get anything from them as there is no power to them

hence why i asked if it was a continuity test as it would give a sound if it was working

do you know what sort of reading they should be

what if they all read but all different readings

totally to confuse the issue as its going to be a pain in the arse as its 4wd with 1 jack and no axle stands at the minute

 

The ABS sensors work on the principle of magnetic induction. The sensor consists of a magnet mounted in close proximity to a toothed "reference ring" that spins at wheel speed causing a "sine wave" (a low-voltage rhythmic pulse) to be generated by the magnet. Your picking up this pulse on the multimeter

Other than that yes the multimeter will read something (which is all you need to know to see if its working) it will either read or not.

As for the 4x4 thing take it out of gear to spin the wheels

 

right ok

will get this done tomorrow

thanks mate

 

ok

ive just tested te sensors as you mentioned mate

im not getting anything on all 4 when i turn the wheels

the only thing that flashes is the minus signal when i turn the wheel

not getting any numbers and all 4 wont of gone down like that surely

the meter is set to the black cable in 200ma socket
and then set to 200m on AMPS DC

is this right

 

Try setting it to voltage then, something low....................I did this AGES ago on another car and i dont have the multimeter and car to hand for a couple of weeks to have a play!

If nothing is coming up, check the resistance across the two pins. Fried sensors tend go open circuit as the fine wire at the coil end melts.

 

well, if ya find out let me know as im gunna do mine soon.

 

you can't read a current like that - a current can only be present if you have a voltage across a resistance - and you've disconnected the sensors from everything

 

ok aside from V=IR what would i have picked up when i was doing this then?

just seen this on the net so seems like its has to be set to voltage AC then give that a shot

"connected to both terminals, select "AC Voltage" and spin the wheel by hand. You should see at least 100 mV, with voltage picking up as wheel speed increases. If you don't see this, the sensor needs replacement."

 

right stil problems

thought i solved it got the abs light to go out but until i hit 20 - 30mph the abs light comes on

now before i changed a sensor the abs light was on instantly now it goes out after 20secs as it should be then comes on when i move

anymore ideas

how much are the sensors new from ford?

 

so I = V/R and as V is quite small and R is quite large, I is really quite small

 

Nick, unless I am mistaken (my university days are in a dim and distant future), the rotation of the wheel will create a small alternating voltage due to the magnetic nature of the sensor (like a dynamo).

The ammeter bit of a multimeter is in fact a very low value resistance across which a voltage is measured by the meter. Using the V=IR formula, the meter turns the voltage measurement into a current since it knows the value of the resistance.

So the resistance in the ammeter will enforce a small current to be generated, but I am not sure it would be of any relevance as it would be the only part of the circuit (probably what you meant).
The purpose of the meter's resistance in a full circuit is to introduce as little disruption as possible (hence its small value as it is wired in series), in this case, it's the only resistance, so by definition it is altering the circuit significantly.

Measuring voltage makes a lot more sense imo, which is what andy said afterwards

 

Indeed Greg...........all my physics at uni has long evaporated from my head so cant think it through logically

But I promise you will get a reading of some sort. Its annoying that i am not am not able to try it on my car and confirm the procedure one way or the other as i am away from the car at the mo until the weekend

 

you could both be right, my university days are also long behind me.

off out now, to try the new honda civic - looks wicked

 

Right, gunna have a go at this tomorrow. So what settings does my multi-meter have to be on? As im SHITE at electronics.