Weird DSC issues - lights but no codes

F

Fabiantir

Member
!!!Long post incoming!!!

A continuation of sorts from this thread, focusing on DSC issue and hoping to get some diagnostic tips!

The patient
  • 2006 E86 3.0si sport, manual, built Dec 06
The problem
  • I have yellow 4 warning lights - run flat indicator, ABS, traction control, handbrake
When did it happen?

I was reversing slowly and slightly uphill into a parking bay and almost stalled the car. Lights came on straight after. Parked up and switched the car off and on again - lights gone. Returned to car later, lights stayed on.

A few days prior I had the battery disconnected/reconnected a couple of times while I replaced oil filter/cooler gaskets, mickey mouse hose, PCV pipe, and small DISA. I don't recall touching anything that could relate to the DSC or brakes, apart from that line that runs from the vacuum pump to the servo that routes through the intake manifold.

What have I checked so far?

Codes:

5E4E DSC: control unit, DSC sensor; adjustment values
5DD1 DSC: control unit, run flat indicator
5DD2 DSC: hydraulic unit: adjustment, DSC unit (valves)
5DD0 DSC: hydraulic unit: adjustment, DSC unit (valves)
5E59 DSC: control unit: recode
5DF5 DSC: control unit: internal fault

I also have these - surely they aren't related but including them just on the off chance it gives any clues

16 LSZ2: wire/switch, turn indicator, short circuit to earth
17 LSZ2: wire/switch, main beam/headlight flasher, short circuit to earth
22 LSZ2: headlight V.A.C., front load sensor, short circuit to earth
18 PDC: voltage, converters in general (been there since I bought the car, sensors have never worked)

Live data:
  • Wheel speed sensors - working, all display the same speed. Cruise control and speedo still working fine.
  • Steering angle sensor - reads normally in both directions
  • Rotational acceleration sensor: seems to be working fine
  • Brake pressure sensor: not working, no reading
  • Longitudinal acceleration sensor: not working, no reading
  • Lateral acceleration sensor: not working, no reading
Others
  • car has full brake fluid reservoir, fluid looks alright and is about 18 months old (was done Sept '24 by prev owner)
  • brakes work fine, will bring the car to a stop hard with no fuss
  • steering feels fine
  • don't hear weird noises
What have I tried?

1st step:

DSC pump actuator test with my scanner tool (Launch creader elite).
I heard it run for a couple of seconds, lights went out, codes cleared, got readings from lat/long acceleration sensors and brake pressure sensors. However the lights came back a couple of days later only now with no codes.
The scanner also can't/won't find the DSC menu anymore with automatic health report - seemingly I could only do this when there was a code present. If I manually select the model and then the DSC ECU, I just get an error on the scanner.
It seems I don't have a way to make the ABS pump run as it stands.

Subsequent steps:
  • Steering angle sensor reset - scanner says it was completed successfully. Went for a 40 min drive, lights still on
  • Brake pressure sensor matching - scanner says completed successfully, lights still on
  • Checked all fuses related to DSC according to fuse guide. All fuses fine, lights still on
  • Brake really hard from speed and mash throttle out of slow corner to try and trigger ABS pump - not even sure I broke traction much if at all, maybe I need a looser surface...
  • Bang DSC pump with a metal pipe - no difference, lights still on
  • Looked for brake pressure sensors to clean contacts - can't see them on the servo? Where I would expect to find them is blanked off
Having searched extensively in various forums, it seems one can experience a wide range of DSC issues and codes, but I haven't found any threads where someone has all 6 of the ones I got.

I am really hoping someone who knows these cars well can give some diagnostic directions taking into account what I tried already. Ideally I'd like to keep the parts cannon on standby until I can narrow it down to something specific. I am all ears, I will try (almost) anything.

Thank you to anyone who read this far and a big thanks in advance to anyone willing to get into this ❤️
 
Usually if the scan can’t find a module it is because that module is dead or dying. Obviously if it cannot see the module it cannot show any codes from it.
In this case that would possibly point to the DSC module failing.
The separate brake pressure sensors are only on prefacelift. Yours has them in the DSC unit.
 
I think those 5DD codes support a failing module principle especially as you can’t connect to it

I would get to someone who has inpa/ista to see if that can connect to the module and read it
 
That makes sense if it's dead. From memory, you have to code a new module to the VIN of the car right?

I think I will try unplug, clean contacts, and re-plug + disconnect battery for a bit just on the slim chance that helps...
 
If you buy a new unit yes you will need to code

In the past I have bought a like for like unit, opened the existing and donor units up in to the two constituent parts (the mechanicals and the electrics) and swapped them to create a working unit that doesn’t need coding

It’s only a few bolts on the ABS unit
 
I've read about frankenpumps - seems like a good option. Would I be right in thinking that if the module/electrics are toast, that coding will always be required? Presumably the bit coded to the VIN is the electronic part rather than the pump
 
Correct

But the bit that fails as far as my experience is the mechanical part
 
From what you've seen, could failure of the mechanical part cause the module to stop communicating, or result in the codes I had?

Definitely going to need to find someone with ISTA and check it out, or download it myself maybe
 
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