How (un) likely is this ??

Oops, meant to say that I was told that the common ABS module failure was on earlier cars.

David

A quick google for "E90 ABS module" got

and a stack of other similar results, with no apparent split between early and late E90, so it's clearly not unknown on your car.

I thought they'd likely be hall effect sensors which are active devices and may not give any meaningful reading on a DVM - unless powered up?

If they are VR sensors, a DVM resistance reading could be of use.

I 've just been to the local stealer (BMW), and spoke to a guy I am quite friendly with whom was a Service Adviser for 3.5 years, but now is in the parts dept...

He said that the 4 pot cars can have a problem with the DSC module and that there is a repair kit for them. Also, it is rare for the 6 pot cars to have a problem with the DSC module, and there is not a kit for those :-( new unit £1500 :-((((((

Ha had never heard of three sensors going at the same time.

The codes I managed to extract from the car are:

A0C1 (A zero C one) A0C2 A0B5

49F2

None of these (that I can find decoded) are pointing to the DSC module itself.

I cleared them, went for a drive and they have not returned, but still have all the warning lights illuminated.

Dave, the sensors have two terminals, three of them are open circuit, whereas the new-ish one was 385K ohms.

Thanks Adrian and Dave for your replies.

David

To me it sounds like it's the one that's been replaced that's failed again.

If that's the ECU the OP has, then it's the same ECU (Mk60) that commonly fails on Golf V (etc). In that case, it's a pressure sensor in the ECU that fails- BTDTGTTS- and certainly on VAG applications it logs a specific fault:

VCDS Version: Release 11.11.2 Data version: 20120126 Thursday,08,March,2012,17:49:39:23633

Chassis Type: 1K0 Scan: 01 02 03 08 09 15 16 17 19 25 42 44 46 52 56 62 72

VIN: VSSZZZ1PZ6R0XXXXX Mileage: 107140km/66573miles

------------------------------------------------------------------------------- Address 03: ABS Brakes Labels: 1K0-907-379-MK60-F.lbl Part No SW: 1K0 907 379 AA HW: 1K0 907 379 AA Component: ESP FRONT MK60 0102 Revision: 00H13001 Coding: 0006786 Shop #: WSC 06441 785 00200 VCID: 71E3A0F868B23BB

1 Fault Found: 01435 - Brake Pressure Sensor 1 (G201) 012 - Electrical Fault in Circuit

and the repair kit is the answer. However, the OP should get the car scanned to investigate. As has been suggested below, looking at the newly replaced sensor and wiring might be a good idea.

Yes, I agree, it does sound more likely that one sensor has failed rather than the other three.

Thanks

David

Although the unit is not the same (I am led to believe) and no repair kit is available for my unit, I will get the car scanned with a better diagnostic.

Thanks Chris.

David

Did you disconnect the sensors before testing, or test in situ? If you're testing in situ you're testing the wiring/etc as well as the sensor. So you could just be detecting the fault that is further up the chain.

Theo

En el artículo , David escribió:

Did you test them on the car? Maybe the 'odd one out' just happened to in the position where the wheel triggers it?

Yes, I tested them in situ, just disconnected.

I also checked for milli volts (AC and DC) and milli Amps (AC and DC) by spinning the hubs, as well as changing resistance. Also used diode check setting too, both ways.

I am going to take one out of the other BMW to substitute it with a known working one.

Thanks

David

Tested in situ with the plug disconnected, and span the hubs, too.

Thanks

David

Do you have a frequency counter on your DVM - or did you even see a reading on AC volts when you spun it ? A VR sensor which is a passive device will give an output with no power to it. A hall effect - which is common as they will read at very low speeds - not.

There are two terminal hall effect sensors.

I'm only hypothesising. A VR sensor won't read at very slow speeds. A hall effect will - so that's what I'd use for brakes.

A VR sensor is just a coil in essence and I'd expect the DC resistance to be no more than a couple of thousand ohms at most.

David, I would suggest you track down a GOOD BMW dealer or specialist and have them analyse the car. It would be worth the £50 or so to pinpoint the problem rather than employing a parts-darts attack.

Tim.

Right, the car is booked in for a proper dealer scan next Thursday, soonest available slot.

The car is Aug 2009, and in May 2011, the parts numbers for the sensors changed. The old part was superseded. The new-ish part on the 3 series is the later part number.

The other car was made in Sept 2011, and has the later part numbers. Both cars use the same sensors, old part numbers and new.

I tested the other car sensors and they measured the same as the new-ish one on the 3 series.

Using a different DVM, I found that the three sensors I thought were open circuit, are not, but using the diode check function, the forward volt drop is 1.8 volts versus 0.55 volts for the newer part numbers.

The tech guy at the dealership thought that the new part should be compatible with the old parts.

Using the on-line BMW parts catalogue, I found that there *is* a repair kit available for the DSC module on the 6 cylinder models.

Code 49F2 has re-appeared though. The text with that code is: "message (speed ce)"

The DSC module is running with "substitute values" for the values of the wheel sensor outputs, but the speedometer has not malfunctioned at all.

I cannot think of any more developments.

Thank you all for your help, input and interest.

David

FWIW, this implies some electronics inside so you're probably finding a voltage drop across a transistor in there. Basically, reading with a DVM gets you nowhere.

I was playing with the suspension level sensor of a Discovery that just looks like a variable resistor in a box with an arm strapped to the trailing arm, but it gave nothing away with a meter and had a whole little circuit board inside it when I hacked it open.

Got any more info? I was looking at these for use in pitch/attitude display for testing aero mods.

Looking at second hand one of E-bay there appear to be early and late types. The late ones have a 9 pin connector that looks like CANbus. Early ones appear to be 3 wire.

En el artículo , Scott M escribió:

Might it be CANbus? 5 wires - power+, power-, data+, data- and ground.