Abs Issue.. Module??

[Broden21]

Hey,

I have a 2006 Freightliner Sprinter 3500, I have an ABS light on,

My garage looked over everything.. Lights are properly working, sensors are clean and wires are not cracked. The Left Front wheel was reading lower volts when they would spin the wheel. They replaced the sensor, still having the same problems. When they connect their scan tool to the vehicle they can read all of the sensors besides the LF. My garage seems to think its it needs an ABS module. I really don't want to throw money into a new module for it not to work.

Any suggestions?

 

[SneakyAnarchistVanCamper]

I think they're pulling your leg. How would an abs module have anything to do with the voltage from a wheel speed sensor (a tiny generator)? Absolutely no, I would not replace the abs module, that's not how it works, the sensor itself is a tiny generator and if isn't putting out proper voltage that means it doesn't have a proper gap to generate voltage, the sensor itself is faulty or non oem, or if the low voltage reading is being taken further back on the wires rather than back-probed at the connector, then of course the wires can be at fault too.


I'm betting $10 on improper gapping of the wheel speed sensor, a short/damage/dirty connection in the wheel speed sensor wire, or sensor was replaced with non-oem part.

 

[Big Dunk]

Are non-oe sensors that bad? I mean, I was told that my crank position sensor is throwing an error, and I've got to replace it. (it is a 2010 Dodge Sprinter, by the way). And I was planning to buy an aftermarket one....
SneakyAnarchistVanCamper, man, you think it is a bad idea?
Broden21, sorry for posting in your thread, man, just wanted to clarify this posint for myself...

 

[SneakyAnarchistVanCamper]

Are non-oe sensors that bad?

Yes, they are the devil incarnate. Responsible for some sprinters gone to the junkyard prematurely. Responsible for thousands of dollars of shop troubleshooting. The reason is because for say, a hall effect sensor, it needs to be manufactured exactly to specification so it returns the right values. An aftermarket replacement would still be a hall effect sensor, yes, but could return wildly different readings or not fit with the exact clearance (like in a wheel speed sensor). I would rather rely on a bicycle than a sprinter with a non-oem crank sensor.

 

[autostaretx]

The wheel speed sensors are simple magnetic pick-up (not Hall effect).
Here are the training pages on them:







--dick

 

[Broden21]

I think they're pulling your leg. How would an abs module have anything to do with the voltage from a wheel speed sensor (a tiny generator)? Absolutely no, I would not replace the abs module, that's not how it works, the sensor itself is a tiny generator and if isn't putting out proper voltage that means it doesn't have a proper gap to generate voltage, the sensor itself is faulty or non oem, or if the low voltage reading is being taken further back on the wires rather than back-probed at the connector, then of course the wires can be at fault too.


I'm betting $10 on improper gapping of the wheel speed sensor, a short/damage/dirty connection in the wheel speed sensor wire, or sensor was replaced with non-oem part.

Ill double check about the OEM part or not. I did find another ABS module, $200 I'm half tempted to just buy it to take that out of the equation.

 

[Broden21]

Ill double check about the OEM part or not. I did find another ABS module, $200 I'm half tempted to just buy it to take that out of the equation.

I just confirmed that the sensor was an OEM sensor. They also switched the left and right sensors. The RF sensor was showing low voltage and the LF was reading correctly. Which tells me that the spacing on the LF is correct.

The rechecked all the wire for any signs of wear. They found nothing. The shop that does my work is very knowledgeable when it comes to sprinters. I do trust them.

Anything else you can think of?

 

[220629]

I just confirmed that the sensor was an OEM sensor. They also switched the left and right sensors. ...

They switched electrical connectors over and the problem remained LF, or they physically removed the sensors and changed them side to side?

...
Anything else you can think of?

A higher level shop scan tool should be able to show the sensor wave forms, not just voltages. That should eliminate the ABS sensing module signal conditioning from the mix. If the wave forms show good, then that is another indication pointing to the ABS module unit. If the wave form isn't right, there could be a tone ring related problem eg. magnetic debris, or possibly sensor spacing.

Full disclosure. I haven't needed to troubleshoot my wheel sensors other than after I deformed the LR tone ring.

vic

 

[SneakyAnarchistVanCamper]

Ah yes, the tone ring could be damaged too. If you back probe the WSS connector, and see low voltage there, the problem has to be either the WSS gap, sensor faulty, or the tone ring is faulty, I would think. Because it is a little generator, that's where the voltage originates from. So intead of measuring WSS voltage with a scanner reading at the ABS module, back probe it with a snap on on the graphing function.

 

[Broden21]

Ah yes, the tone ring could be damaged too. If you back probe the WSS connector, and see low voltage there, the problem has to be either the WSS gap, sensor faulty, or the tone ring is faulty, I would think. Because it is a little generator, that's where the voltage originates from. So intead of measuring WSS voltage with a scanner reading at the ABS module, back probe it with a snap on on the graphing function.

I just confirmed they switched the FR sensor over to the FL side, that tone ring in the LF is working correctly. All signs are pointing to the Module, I should be getting the new one on Thursday. ill let you guys know the outcome.

 

[ptheland]

I just confirmed they switched the FR sensor over to the FL side, that tone ring in the LF is working correctly. All signs are pointing to the Module, I should be getting the new one on Thursday. ill let you guys know the outcome.

That doesn't make sense.

If they swapped the two front sensors and the problem stayed with a sensor, that indicates the problem is that sensor. I absolutely would NOT change out the ABS module after that test.

It doesn't matter if that sensor is new. Get another one and try again. It wouldn't be the first time that a new part was defective out of the box.

 

[calbiker]

Just speculating, you could double check the sensor voltage by unplugging the sensor and spinning the wheel while measuring sensor voltage with an oscilloscope. The sensor output may need a 10k ohm load resistor. You need to compare that waveform to the known good sensor.

 

[SneakyAnarchistVanCamper]

I just confirmed they switched the FR sensor over to the FL side, that tone ring in the LF is working correctly. All signs are pointing to the Module, I should be getting the new one on Thursday. ill let you guys know the outcome.

How would they know the tone ring is working correctly unless they were reading proper voltage at FL after swapping the sensor with FR? In that case I agree with ptheland, that would mean the sensor is faulty. The wording kind of leaves it up to the readers interpretation.

 

[Broden21]

Problem resolved....

I got the ABS module from the junkyard yesterday. My shop put it in today. That solved the problem, All sensors are reading correctly, and I have no ABS lights on the dash. I ended up paying $240 with shipping for the part.

 

[Big Dunk]

Yes, they are the devil incarnate. Responsible for some sprinters gone to the junkyard prematurely. Responsible for thousands of dollars of shop troubleshooting. The reason is because for say, a hall effect sensor, it needs to be manufactured exactly to specification so it returns the right values. An aftermarket replacement would still be a hall effect sensor, yes, but could return wildly different readings or not fit with the exact clearance (like in a wheel speed sensor). I would rather rely on a bicycle than a sprinter with a non-oem crank sensor.

Man, thank ya so much!!! As I have ordered a crank position sensor thinking it is a cool idea to save some cash (here's what it was), and it is on the way to me, so I will be sure to send it bck to the shop as soon as it arrives.

 

[Goofy foot]

Wise choice, Grasshopper ! Confuse Us says.....