been away at work for the day and on getting picked up from the airport I was greeted by the missus saying ' I think we have a problem with the car' oh dear or words to that effect says I.

the bongs have been - HDC fault not available
-Transmission fault traction reduced
- engine speed sensor A fault and rear right wheel sensor - the engine speed sensor appears to have cleared
- park brake fault

dash lit up like blackpool lights and car on lowered suspension.


the following codes were cleared and reappeared quite quickly and the car bongs the above again apart from the engine sensor issue.

ATCM codes - u0401 invalid data from ECM/PCM
-U0402 invalid data from TCM
-U0416 invalid data from vehicle dynamics control module
-U0403 invalid data from TCM
-U0421 invalid data from suspension controle module

park brake code - u0416 ^as above

RDCM rear diff code - u0122 (fuel and air metering ) lost comms with vehicle dynamics control module

TCCM transfer case code u0136 - (fuel and air metering ) lost comms with diff control module rear.

I also had a rear right wheel speed sensor alarm but that has cleared -

Now then has anyone got a clue for me where to start on this ??

ie could it be a common issue giving all of the above


any advice/help is welcome

thanks in advance

ps my first train of thought is the right rear wheel sensor is duff and f@@@@ing everything up

First port of call is to check the battery voltage and charging rate... Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

battery shows 14v when cars running but I will stick it on a conditioner for the night

thanks for the prompt

Sounds pretty typical steering angle sensor or wheel speed sensor.

^^

speed wheel sensor is my best suggestion too as its still showing a DTC - going away to work for 2 weeks so will sort once back .

Did this clear itself?

Any more trouble?

still at work , will update once sorted

Well I have changed the right rear abs sensor - eventually - it broke off in the hole and a drill was needed to get the damn thing out.

anyway the problem has not gone so any one have any ideas ?

the codes showing are :-

ATCM U0401,U0402,U0403,U0416.

TRANSFER CASE U0122,U0136

REAR DIFF U0122

PARK BRAKE U0416

VEHICLE DYNAMICS - RR SPEED SENSOR CIRCUIT C1A93

they mostly appear to be comms issues

any pointers from someone who knows what the likely cause/culprit would be good

cheers

Time to update this now as everything is sorted

the first issue was a failed right rear speed sensor , this I changed with a part from ebay which was listed as for my car

I changed the sensor , but the original was stuck in place so had to drill it out . After fitting new sensor still had the 3 fault lights and no signal from RR speed sensor , sent car for diagnostics to independent in tyne and wear, after 2 hours diagnostics they told me abs ecu goosed all circuits are ok all speed sensors are ok MUST be abs ECU.

rather that take their word for it and fork out about 2k I decided to fit a second hand unit, this was after dismantling my ecu and finding nothing of obvious concern with the naked eye.

I fitted the second hand ECU and still had the no signal from RR speed sensor and the 3 lights of doom - so either the ECU has the same fault or the fault lay elsewhere - I double checked all resistances and circuits to each speed sensor and discovered eventually that the one I had changed was way above the others. so either a failed new sensor or the wrong sensor fitted.

It turned out that the wrong part had been fitted by me due to the listing on ebay , the sensor should have been ssf500021 , but the vendor had supplied ssf000021 - arghhh .(how had the independent well respected garage not picked up on this I don't know as the resistance checks should have been part of their diagnostics)

once the proper sensor had been fitted I managed to have all speed sensors working BUT after a few yards of driving still got the bongs and 3 lights - this turned out to be a new code that was the pressure sensor within the abs module failure - this was a new code and I guess it came about after I had really stamped on the brakes to test whether the abs system was working a few days before .

I then decided that the only thing to try was to change out the HCU as the pressure sensor circuit is both in the ECU and HCU - now the problem is fixed after a lot of about.

the morale is - check check and double check parts are correct - If I had checked correctly all my woes would have been resolved with a simple sensor change out for about £50 instead I have bought two new sensors which are not for my car and wasted time and most likely a good abs module that wasn't needing changing in the first place.

at least the problem is sorted now.


ps also discovered some scrote has stolen both rear wheel arch bits of trim that clip on the lip of the arch


ETA - lots of help from Patrick at GAP who had the patience of a Saint

Glad you got it sorted, sounds like a right pain in the bum.... Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Pete

it was a bit of a nightmare tbh - especially with misinformation and wrong parts , a catalogue of which lead me down the wrong path.

One of the things I also changed out was the brake pedal switch (this can also cause some of the similar/same issues) this is a bastard to get to and you need to be somewhat of a contortionist to change it out.

the thing I was trying to avoid was changing out the HCU as I expected to need to take the car to get bled properly using the software at a garage - fortunately I have encountered no issues whatsoever - the brake pedal is ever so slightly spongier than it was previously , this is without even carrying out any bleeding!

I shall do it at the weekend when more time is available , but I am really surprised that no other issues , all I did was put clingfilm over the reservoir top to hold vacuum to minimise loss , and on disconnect of brake pipes at HCU plug each open end with bluetack to stop air ingress , I then used a syringe to prime the HCU through each port before reconnect and all is good.

I also tested the brake efficiency and all was well so went to a nice steep hill and used HDC to get the system going and all is working fine.