Discovery 2 ACE - DTC 33 Directional control valve fault.

DaryllD2 · Jul 13, 2023

I have been having problems with an amber light which is deciding to reside on my dash intermittently during most medium/long drives (Not always).

I have read live data with hawkeye. These numbers are from car at idle, stationary :

Reverse switch IP - Not reverse
Main relay : ON
Warning lamp : OFF
Engine speed : 749 rpm
Road speed : 0mph
Upper lateral acc : -0.01 G
Lower lateral acc : -0.09 G
DCV1 : 0.01Amps
DCV2 : 0.01Amps
Battery Voltage: 14.01volts
Pressure control valve : 0.09Amps
Pressure sensor : 23(Fluctuating, can get even higher) don’t know if this is okay?
Residual pressure : 8.60 bar (just after a drive)
System pressure : 9 bar ( fluctuating between 7 and 10)

Maybe someone can make sense of maybe why it might be throwing up this fault code. Want to try diagnose before throwing money at rebuilding the block.
Any help is greatly appreciated as I’m new to this forum stuff.

sierrafery · Jul 13, 2023

As long as the lamp was off those reading are all within accepted limits so irrelevant for any diagnose ...if that DCV fault code was retrieved with hawkeye means that there might be an intermittent bad contact on the DCVs circuit. Read data with warning lamp on next time

DaryllD2 · Jul 13, 2023

sierrafery said:
As long as the lamp was off those reading are all withing accepted limits so irrelevant for any diagnose ...if that DCV fault code was retrieved with hawkeye means that there might be an intermittent bad contact on the DCVs circuit. Read data with warning lamp on next time

Going to take it out for a long drive tomorrow and most likely I’ll get the chance to read live data with the amber on. Stay tuned mate, thanks for the fast response as well!

MJI · Jul 13, 2023

May be worth cleaning filter and changing Fluid.

DaryllD2 · Aug 26, 2023

I took a little time away from my ACE faults while I used the warmer weather to get stuck a new under seal for the winter.

Now that I’m back into it, I have changed the fluid and filter for the system.
After taking the car out for a drive my amber lamp has lit up once again. Giving me fault codes such as :
DTC 33 Directional control valve fault
DTC 48 Main relay fault

Like you advised, this time I read the fault codes with the lamp turned on. The live data is as followed. (All data from Hawkeye)

Ignition switch : ON
Reverse switch IP : Not reverse
Main relay : OFF
Warning lamp : ON
Engine speed : 749RPM
Road speed : 0MPH
Upper lateral Acc : -1.43G
Lower lateral Acc : -1.43G
DCV 1 : 0.01Amps
DCV 2 : 0.01Amps
Battery voltage : 0.03Volts
Pressure control valve : 0.08Amps
Pressure sensor : 0.00bar
Residual pressure: 0.30bar
System pressure 0.00bar

Any responses to help get to the bottom of this is greatly appreciated as always!

Stanleysteamer · Aug 26, 2023

DaryllD2 said:
I took a little time away from my ACE faults while I used the warmer weather to get stuck a new under seal for the winter.

Now that I’m back into it, I have changed the fluid and filter for the system.
After taking the car out for a drive my amber lamp has lit up once again. Giving me fault codes such as :
DTC 33 Directional control valve fault
DTC 48 Main relay fault

Like you advised, this time I read the fault codes with the lamp turned on. The live data is as followed. (All data from Hawkeye)

Ignition switch : ON
Reverse switch IP : Not reverse
Main relay : OFF
Warning lamp : ON
Engine speed : 749RPM
Road speed : 0MPH
Upper lateral Acc : -1.43G
Lower lateral Acc : -1.43G
DCV 1 : 0.01Amps
DCV 2 : 0.01Amps
Battery voltage : 0.03Volts
Pressure control valve : 0.08Amps
Pressure sensor : 0.00bar
Residual pressure: 0.30bar
System pressure 0.00bar

Any responses to help get to the bottom of this is greatly appreciated as always!

I am not an expert like @sierrafery but I too have the amber light come on intermittently and my Foxwell (yep not a hawkwind or tother'un) simply says "main relay" so one fine day I'll swop it for one of the other identical relays and see if it comes on again. But I can go for ages and many miles before it comes on again.
Weirdly mine only started doing this when I was towing a car trailer with a car on it and an anti-snake device.
Doubt this is significant though.

MJI · Aug 26, 2023

Check cabling first.

Low pressure and low voltage. Hmmmm.

Do you have a spare ecu? If not grab one while you can from ebay.

If just low pressure would have suggested pressure sensor.

sierrafery · Aug 26, 2023

DaryllD2 said:
Pressure sensor : 0.00bar

seems very like the pressure transducer is gone, quite common, you'll have to replace it to rule it out and hope it's not a wiring issue http://www.discovery2.co.uk/ACE_transducer.html

DaryllD2 · Aug 26, 2023

Thanks for the fast responses, going to replace the pressure transducer some time in the coming week or so and I will be back in touch shortly. Stay tuned fellas, thanks again.

DaryllD2 · Dec 11, 2023

Just checking back in on this thread as I tent to see a few of these problems go seemingly unsolved, however it’s probably just because they diagnosed the problem and they didn’t need to post the solution. Changed the pressure transducer out for a new one. About 1000 road miles and no lamps on.

Thanks again fellas!

Discovery 2 ACE - DTC 33 Directional control valve fault.

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