Hello People of the Forum

As always your help and understanding is appreciated

I have a 2006 L322 which is suffering from intermittent heavy steering , normally at idle it is most noticed, pulling away from junctions ect...

So far i have replaced

Servotronic valve
BCU
Cleared all faults
Reset Tansport Mode
Pulled rack off and sent for recon (i really would not recommend that, a whole day with a bag of spanners)
Pressure tested pump (it's fine)

I am really at the end of my tether, the only indication i have left are occasionally i have a HDC inoperative message and as the BCU gets its road speed information from the ABS ECU i wondered of this was at fault, not communicating correctly to the BCU ?

Also if anyone had information on the pin outs to the BCU from the Servotronic valve , they would be most welcome so i can check for any open circuit ?

2nd Last option to try is to put a 12V feed to the servo valve to see if i get permanent light steering ?

Last last option is to drive it to a field and burn it, but i do like the old girl !

Anyone shed some light for me i would really appreciate !

Thank you all

Neil

Last edited by gavinn on 21st Feb 2019 8:18am. Edited 1 time in total

Any fault codes?

No Codes at all i am afraid

Was the replacement BCU a new one or secondhand ?

I've got a the same problem & think it's probably the BCU that's faulty.
I was monitoring the voltage at the 2 pins on the Servotronic valve to see if I could work out what was happening.
Max voltage I've seen is 7.5 volts, so I'm also going to try applying full battery voltage to the valve and see whether I get full steering assistance.
My only concern is if the valve is only designed to run at eg 10v (so that low battery voltage doesn't effect steering assistance). Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 151,000 miles & now sold
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

Hi

I fitted a brand new BCU Part Number YWC000923 which made no difference, i now have 2 BCU's so if you know anyone who wants a known good second hand unit my old one will be on e bay soon, i also have a known good servotronic valve as changing that made no damm difference as well.

Let me know how you get on with your full voltage test ?

Just noticed you are in the Midlands, i am in Birmingham B27 so if you want to try my old known good BCU you are welcome to nip around, save you the cost of buying one ?

Cheers

Neil

Symptom just noticed

Went out to the vehicle this morning, turned the key, fired up , steering light as a feather, turned it off, restarted it, STEERING NOW SUPER HEAVY, go figure it went from good to bad in 10 seconds between restart !

Neil,

Have you thought of checking the wiring / connectors between the ABS ECU & BCU ?
I'm not sure where the ABS ecu is located, but if the wire that transmits the speed signal to the BCU is partially damaged, it might be possible that the BCU is not always getting the signal it needs to decide when to adjust the output to the servotronic valve.
I'm assuming the ABS ecu output on mine & yours must be OK, as I'm fairly sure it would throw up fault codes if not (however, that could be a rash assumption).

It might even make sense that our symptoms are more likely to be caused by an intermittent wiring fault than the BCU intermittently generating a different output to the servotronic valve when given a "slow speed" signal by the ABS ECU.

BTW : Yes, I'll update here when I try 12v on the servotronic valve (will be this week as I've decided to pull my finger out and make progress after 12 months of messing about & deteriorating shoulder strength - lol) Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 151,000 miles & now sold
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

Yes i am beginning to suspect wiring as well, if i could get hold of a wiring diagram for the BCU i would like to bell out the connections to the ABS ECU and the Servotronic Valve

What model is your RR ?
Our's is a 2006 Nov TDV8 (ie Facelift) & I've got all the relevant wiring diagrams now for it, but if yours is pre-facelift I think there are wiring diagrams in the Wiki Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 151,000 miles & now sold
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

Mine is the 2006 Facelift model , ie touch screen and TV in the dash.

Its the V8 4.4 Petrol Vogue, i would expect most wiring would be the same as yours apart from the obvious engine ...

The BCU /ABS/ Steering are all the same part numbers across petrol and diesel

I think i have worked it out.

Steering ok on start up when vehicle is cold (High Revs)
When vehicle has warmed up steering goes to zero assist when stationary (Low Revs)
When vehicle is being driven steering is ok ish.....(High Revs)
When foot is taken off the gas for a corner, steering goes stiff (Low Revs)
Knocked it into neutral for a corner and kept the revs up steering fine.

So all engine speed related, it must be the pump, bloody thing was ok when tested, intermittent faults eh !!!

Now to order and fit a pump !

Neil,
I'd suggest trying to get the pump output pressure checked before investing in a replacement.
There are others on this & other forums with similar symptoms who've also changed the pump & got no improvement in .

Here's the wiring diagram for the 2007MY versions like ours.
It's different to the earlier model years. The speed signal appears to come from the instrument cluster NOT direct from the ABS ECU

The General Electrical Module (GEM) is another name used for the BCU.
Colour codes are B = Black, R = Red, W = White, N = Brown, S = Grey

BTW Have you just tried disconnecting the Servotronic valve to see what it feels like ?
Might not add anything as from your description you are getting varying assistance at different speeds - so it's unlikely to be wiring to the servotronic valve or the valve itself Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 151,000 miles & now sold
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

Thanks for the wiring diagram

I am pretty sure its the pump , as it is defiantly engine speed as the symptoms are identical when the vehicle is stationary , ie low engine revs no PAS, High engine Revs good PAS, so if the vehicle is not even moving it can not be related to speed ?

Apologies if this sounds stupid, but you haven't taken fuse 41 out have you, the one for the rear wiper?

Fuse 41 is in , i did take it out to check and it was fine.

As the steering issue is directly associated to the engine speed i am still leaning towards the pump , interesting thought that the serpentine belt used to squeal when started up from cold , now its deathly quiet, only just noticed that , maybe the pump has no resistance at idle ?

Range Rovers, don't you just love them.

Steering is now like triggers broom all original apart from New, Rack, Servo Valve, BCU, also did this weekend new Disc's all round, new pads, handbrake shoes, front lower ball joints, and of course the "service" item of rear hub bushes !

Even cleaned the interior, found my lack of top end power was caused by the mud build up behind the accelerator pedal !!