ABS sensor testing..

[LamboSE5]

I got a ABS + Tracs Off light(s) on issue that started a few days ago. Abs module is a brand new rebuilt not even a year old so I'm ruling that out. I've also replaced the front left, not to say it couldnt be that one.

So, my question is how do I test'em properly with a multimeter - what resistance am I looking for for a wheel speed sensor/abs speed sensor (correct me if im using the wrong part name - i think thats right), should the car be on, off, key in pos. 1 etc.

Thanks for any help. I'm gone out to see if I can figure it out in the mean time.

[jimmy57]

Have you inspected the two wire plug that plugs onto abs module from the motor part of the abs unit?
Those wires lose their insulation and when the wires touch that can cause the warning lamps to light after the car rolls through about 15 KPH.
Before the sensors get discussed, tell us when the lamp came on, does it ever go off, if it goes off when does it come on?
Getting codes read from the system might save you a lot of work if the code is not for the sensors. The access to check sensors is not that easy.

[Matty Moo]

LF sensor: pins 11 & 4
RF sensor: pins 18 & 3
LR sensor: pins 10 & 2
RR sensor: pins 17 & 1

Use your spare ABS module to figure out the location of the pins on the connector.

900-1380 ohms per sensor, and you should see voltage fluctuation with the wheel spinning.

[LamboSE5]

LF sensor: pins 11 & 4
RF sensor: pins 18 & 3
LR sensor: pins 10 & 2
RR sensor: pins 17 & 1

Use your spare ABS module to figure out the location of the pins on the connector.

900-1380 ohms per sensor, and you should see voltage fluctuation with the wheel spinning.

Thanks! Are you refering to pins on the ABS module? I need/want to check the ABS 'sensors' themselves...to unclip (or disconnect - whichever is necessary/least trouble) them from location and use a multimeter to check and find which one is not working. Then I'll just order a new one and replace it.. does that sound feasable?

Thanks a lot for the help man.

Have you inspected the two wire plug that plugs onto abs module from the motor part of the abs unit?
Those wires lose their insulation and when the wires touch that can cause the warning lamps to light after the car rolls through about 15 KPH.
Before the sensors get discussed, tell us when the lamp came on, does it ever go off, if it goes off when does it come on?
Getting codes read from the system might save you a lot of work if the code is not for the sensors. The access to check sensors is not that easy.

I haven't inspected any of it yet, lent my jack out and didn't check anything yet. The ABS module is new (new rebuilt) from module master (before I knew about matty moo) so I doubt it's at fault. You mean the black connector the comes off it and plugs in?

[LamboSE5]

So I clicked your link and read the trouble shooting...am I to do the multimeter test on the 'pins' WHILE the abs module is hooked up...I don't think my body can contort that way..
And, key in POS 1, or out of car... or car on?

[Matty Moo]

No...you're going through the harness, not the module. Car doesn't need to be on at all.

[LamboSE5]

Matty - I just went out and looked and had that "ohh-ahh" moment. I'll use the instructions you posted and on your site to see if I can find the problem.

Maybe, I hope, the sensor(s) and/or the...sproket (right?) need to be cleaned and that's all. I'll post what I find.
Thanks Matt.

[LamboSE5]

Hey MVS,

So earlier I tested the sensors via the ABS module's harness as explained at midwest-abs.com in the trouble shooting section (courtesy Matty Moo!). Using multimeter, resistance on 2000ohm range :p

Here are my results:

LF: ~1134 Ohms
RF: ~No Reading(!?) (meter displayed "1". As it does when not connected to anything.)
LR: ~1128 Ohms
RR: ~1114 Ohms

The acceptable range is 900-1380 Ohms...

I double and triple checked everything
I took off both front wheels, and using "ABS sensor safe" brake clean, I sprayed down the harness/plug (red connector in picture) as well as the sensor connector (black with pins in picture).

IMG_0397.JPG

IMG_0398.JPG

Additional:
I tried to remove the bolt that holds the "ABS sensor" in, it broke right of. Or 'twisted' off, below the bolt hole in the sensors 'flange'. Just enough to hold it in, not enough to grab n' twist.
So I just finished cleaning up and tested at the ABS module harness again with the multimeter. I got the same results. (ie: the reading for the Right Front was 'nothing'...displayed "1")
(EDIT: I just realized; did I not even clean the actual ABS sensor? Because I couldn't remove it due to breaking the twisting the bolt head off. I guess I only cleaned the pins for the harness connector? Rediculous! )
Then, I tried testing the two silver pins on the Right Front "ABS sensor", the multimeter showed "1123 Ohms"...Thats gotta mean something right, that mean that sensor is working? I tested the Left Front and got in the same acceptable range as the other(s)

I tested the Red "wiring harness" connectors and they both gave no reading ("1"), guess they're not supposed to.

I'm not sure what this means.... is the Right Front sensor working, but just not relaying signal to the module somehow...that would suggest its the wiring/harness somewhere (or connector) then correct? I took apart the red connector and it looks fine, no signs of anything bad.

IMG_0401.JPG

...edit: might need to drill out that lil' bolt stud I guess.
Haha

[begovic]

Lambo your ABS sensor is fine. Make sure you have good connection on the plug then use volt meter to check resistance on ABS module connector. If still have nothing then check resistance on each of two wires from the sensor connector to the ABS module connector. It is bad connection on ABS sensor plug or you have broken wire between ABS module to the sensor plug.

[LamboSE5]

Lambo your ABS sensor is fine. Make sure you have good connection on the plug then use volt meter to check resistance on ABS module connector. If still have nothing then check resistance on each of two wires from the sensor connector to the ABS module connector. It is bad connection on ABS sensor plug or you have broken wire between ABS module to the sensor plug.

How do you mean? Positve and Negative on the ABS module connector (harness), what would I connect to the Sensor Connector (if both multimeter leads are on the ABS sensor connector) ?

PS that abs sensor harness/wire, where and how does that terminate? It runs up from the wheel into a plastic shroud/harness with other wires on the passenger side one. On the driver side, when I replaced that abs wire, I just cut the old one near the (high amperage) fuse box and spliced the new wire in. But, does it lead to the ecu, or the module itself somehow? Hmm