Hi,
Im helping a friend (thats not very good with computers, so thats why im here, and not him selfe. :-) ) with his 04 Ram 2500 5.9 diesel that has a ABS problem.
The warninglamps (abs and brake) is normally off, but when he starts driving and passes 20 km/h the abs pump will activate for a few seconds then turn off, and when he brakes and passes 20 km/h the abs pump activates for a few seconds.again.
If he keeps driving around 20 km/h the abs/brake lamp will come on.

He got the fault codes checked, and if i remember correct it was the front right sensor, that he just replaced so its new.
It could be a defect one ofcours, but i have searched the internet and found ways to check it with a multimeter.
Measured from the connection at the ABS central:

Driverside: 1.087 ohm and going up/down a tiny bit when wheel is rolled as fast as possible by hand. When measures volt we get max 0.044 volts.
Passengerside: 1.153 ohm (and up and down a tiny bit when moving the wheel), volt is max 0.023 volt.

I think he said that its not that long since the wheelbearing was new either (on the passenger side), but there where a lot of grease on the abs ring (dont know if thats relevant or not tho)
His speedometer has never had a problem BTW.

I guess the system isnt quite satisified with the signal from one of the sensors or something..

Has anyone had similar problem, or maybe know what could possible be the problem?
I have ordered some diagnostic stuff that where supposed to work in this car so we can check oure selves but it hasnt arrived yet. :-)

Regards
Fredrik
Norway
(why my english writing is not 100% on fleek :-P )

 

Your english is actually better than some native speakers. (typers? whatever. )

Scan for codes, see what it's whining about.

 

Thanks for your reply Heyyou!

He did get it checked, and there where an error on the new sensor.
But they doesnt seem that far off concidering what we measured? I mean, they where pretty close,. So im just wondering if the values actually is that fare of so it would be a problem..
Just dont want to buy another sensor if it actually turns out to be something else.. :-)

 

Would be interesting to see what the readings translate to in vehicle speed. If the sensors only range from zero to one volt..... ANY difference is going to be significant.

 

I know 10 mph is equivalent to 16 kph. I'd assume 20 kph would be about 12 or 13 mph. I don't know how the bearing, abs sensor is made on the heavier trucks. On the 1500, the sensor is built into the wheel hub. The sensor is integral to the bearing. Does the wire plug into the harness on one end and into the sensor on the other? I suspect you have a bad unit but I'd check the wires first.

 

Hi,

Just a litte update!
He had it in a garage where they said they had fixed it.

I asked my friend how they did that and he said they had "calibrated" the abs. I was like wtf, i have never heard of that.
We picked it up and he asked them for more details of this "calibration" process. The dude behind the desk said he wasnt sure but it involved some driving forward and backward etc.
A guy that worked there had a van and he said it was common on american cars to do this.

Sound like BS to me but i dont know american cars that well..
When he drove off the lamp came after only a few meters. Lol..

So more investigating is coming up!