Went through the manual and the troubleshooting guide says the ABS pump and sensor are bad. Any other troubleshooting or verification steps I should take before rip and replace with new to me ABS unit?

 

So the ABS pump (and module?) are bad and one or more ABS sensors are bad? That sounds a bit unlikely.

 

Diagnostics say the ABS module is bad, but it looks like that is only sold as a unit with the pump. If the module is bad does it matter if the pump is good or not? Only reason I can think of is parting together because the replacement part may have a bad pump and I can make a working part out of the two pieces.
Sorry I typed a misleading title It should be "ABS pump module".

 

I do believe you can order new pumps but not new modules. I dont know of a reason why you cant replace the module apart from the pump.
But I admit I don't know if I remember anyone doing so.

Just be damn careful that the ABS module has power and that fuses 14, 17, 18 are good and that 17 and 18 have battery power on them. That is, MEASURE BOTH SIDES OF BOTH OF THOSE FUSES to be sure, they are powered by the 50 amp ABS fuse next to the battery.

Then, make sure Pin 4 at the module has 12 volts when the key is "ON".
Then, make sure Pin 6 has five volts on it when the key is "ON".

If any of that is missing, the ABS module will look bad/dead/insane. If any of those are missing, the ABS module is not getting what it needs to operate. I learned a LONG time ago to not trust the procedures in the service manual completely.

 

Thanks for the help once again it was a bad 50 amp fuse and a bad ABS module. Now on to the instrument cluster!

 

Dang, almost solved. Getting a RH wheel speed reading of 0 went through the manual and everything leads back to the module. Is there any source for a new module. Haven't had luck with used ones so far. Also get an ABS SPEED SENSOR NOT VALID error from the BCM error hex code 1268-00

 

DRBIII in abs module gives me a RF wheel speed sensor circuit line Monitoring ESP MK25 code: 1110
RF wheel speed sensor is reading 0 at all times. All diagnostics for testing the circuit back to CAB passed. Replaced sensor since 2 different ABS modules are reporting the same error. I didn't see a test procedure for the hub or checking air gap for proper operation.
I can't find what that error code means and think this is the last electrical gremlin to getting this car working.

 

It might be best to try another scanner and scan the car as a 2004 SLK 320. The DRB 3 emulator gives a weird code that isn't even in the service manual for a defective brake light switch. When I use an aftermarket scanner it specifically says stop lamp switch implausible.

 

@pizzaguy you can use my car for your electronics class

 

I think this is good advice.

 

tried it and got a code c1110 which is for a right front wheel speed sensor. I verified the sensor is sending signal. I am starting to think it might be the actual CAB connector pin? If it isn't making solid contact would explain why everything checks out, but doesn't work when connected. Anyone have a guide on how to remove MB connectors?

 

Went back though all the troubleshooting steps from the manual and everything passes the tests. This leads me back to the ABS pump module, but I find it really hard to believe that I have 2 of those with the exact same failure. Really stuck here if anyone has any further suggestions.

 

still no luck on fixing this. I REALLY don't want to rip the wiring harness apart again. Should I be able to measure for AC voltage at the CAB connector to test the circuit from the sensor all the way up to the CAB? Or will spinning the wheel not generate enough voltage to get a reading? Thoughts?

 

I was not able to measure AC voltage at any wheel to an appreciable amount to test the sensors. Not sure if this is an active sensor or I am doing it wrong but no reliable readings all the way down to 2 volts.
Went through everything again and here is where I am at.
I cut a speed sensor apart so I could access the wires. I get 12v on brown wire, nothing on white signal wire with CAB connected. No shorts to ground or shorts to voltage on either. Continuity to proper pins on CAB connector. All manual troubleshooting steps for wiring pass
I tested a second ABS module and get the same error so that rules out a bad module which is what the manual thinks it should be.
I removed the LF wheel speed sensor at the body connection and when I do that, I get the same error as the RH WSS. Sensor circuit line monitoring error.
Based on the manual I am left with a wheel speed sensor itself or maybe a hub? I ordered another wheel speed sensor and installed with no difference. I don't see how it could be the tone ring. Visual inspection reveals no damage. Don't see a way to check air gap.

Question for this circuit do the wires have to be a twisted pair to work? Not sure how much twist they have after splicing the wiring harness back together.

 

It was a wiring issue. Even though everything pointed to no, I cut the wires and ran a jumper to test. Dang it everything works, now I have to tear the wiring harness apart again to run new wires... At least I know what it is and can fix it.

 

Nope, but now I truly understand what is breaking, but not how to fix it.
When I measure voltage at the body side connector with everything unplugged past it to the wheel I get 12volts on brown - good


Picture doesn't show it, but If I measure with wires connected together (entire harness assembled) I get 2 volts instead of 12 and no speed reading. - Bad
If I cut the wires and remove the wheel side connector and connect from body side connector to bare wires on the WSS via jumpers. I am back to 12 volts and get an accurate wheel speed reading.- good but unusable.

It doesn't matter if the WSS is mounted to the car or not. I always get 2 volts when the WSS connector is attached.

What am I missing that would drop the voltage just because a connector is attached (not even plugged in) the top picture is the connector I am talking about. Cut it off and everything works via jumpers.
I have tested 2 sensors. 1 brand new and same thing happens.

 

Sorry, the entire post is hard to follow. How is it this is not the answer?

And you might make a diagram with "Paint" and label it, the text you are posting is (for me anyway) hard to follow because you appear to use inconsistent terms.
See how I did it in the red circles:

 

Not sure how to diagram out the situation but will try
Scenario 1 - normal fully assembled circuit and sensor - no reading for wheel speed 2v DC circuit voltage
Scenario 2 Normal circuit except jumper wire ran from connector to splice in WSS - no reading for wheel speed 2v DC circuit voltage (test connector)
Scenario 3 - Fully assembled wheel speed sensor (WSS) not mounted to car (trying to troubleshoot for ground issue) no reading for wheel speed 2v DC circuit voltage
Scenario 4 same as scenario 3 except using jumper wires to WSS - no reading for wheel speed 2v DC circuit voltage
Scenario 5 - WSS connector cut off (Picture 1 above of the connector I am talking about) and jumper wires directly from brown white twisted pair connector to WSS striped wires -12v and wheel speed readings.
Example of working setup off the car. Jumper wires go from WSS back to brown and white twisted pair.


All tests done with Key on and CAB connected.
Connector in question is circled in red and is the male side connector (on the WSS)

 

I have no idea what that means. YOu say the Wheel speed connector is cut off, but then you say the twisted pair is connected to the sensor wires and it all works.
So what is the problem?

 

I realize that may have been confusing. Honestly I was confused too as I was getting inconsistent test results
I really figured out end to end this time!
The PIN out for pins 3 and 4 of the ABS connector was reversed for the Wheel speed sensor. I switched positions of the pins and everything is working.
I guess when I connected the jumper wires I just randomly got the right wire to make things work, and didn't really think about the sensor wires being specific since it is basically an open close switch to my understanding.
I never thought the wires would be reversed as I matched wire colors when I soldered a new connector in and never touched the actual wire location in the connector, and it is impossible to tell which is position 3 and 4 from the manual.
Or maybe it is a change over years or aftermarket wheel sensors. Whatever the reason I have speed at all 4 wheels now!