Discovery 2 TD5 - ACE Red Warning Light - No Cirulation In Tank

Hi guys,

I own a discovery 2 from 2003 with an ACE System. Because 2 pipes startet leaking because of corrosion i decided to replace the pipes with standardized pipes and tubes from my local hydraulics store. Because getting everything I needed took some time (and doing the modifications also took time) the System with the block and everything stood dry for about 3 months. The modification now is finished but there are sadly some problems and it doesn't work like before.

Now at first I had 15 errors and an orange light, which are gone after the tip from another forum of replacing the fuses and the ACE-relay. Now I'm down to the only error-code thats left:
"Hydraulic Or Mechanical Fault In Pressure Control System"
I can delete this error and it will stay of until I drive 40km/h, then it will come back. The fluid is sadly not circulating in the ACE-fluid-tank, but there has to be a lot of pressure, as the System starts leaking at the least tightened screw-connection of the pipes and tubes after driving.

I already took out the ACE-valve-block filter and cleaned it with brake-cleaner, let it dry and put it back in. This sadly did not change anything. The filter also looked like almost like new.

Does anybody maybe know what I could do or what else the problem could be? I seriously don't know what else to do and I don't really want to buy a new pump just to try of thats the problem. Its really expensive and I have to take a lot of stuff out again from under the engine hood...

I'm glad for any answer or tip i can get!

TL;DR: Red ACE Warning Light; No circulation in ace-tank; Error-Code = "Hydraulic Or Mechanical Fault In Pressure Control System"; valve-block-filter = clean

Best regards

Hi, if you drove the vehicle without fluid in the system the pump is probably gone, if it just stood there untill you fixe the pipes you need to prime the pump. Undo the banjo at the output pipe, ask somebody to start the engine and when you get good flow there stop the engine, tighten the banjo partially back start the engine again and if you get activity in the tank tighten it fully back and top up the tank then go for a ride somewhere to drive it with many curves both ways as fast as you can to bleed the system then top up again if needed....if you cant get activity in the tank after priming the pump you'll have to replace it

sierrafery said:

Hi, if you drove the vehicle without fluid in the system the pump is probably gone, if it just stood there untill you fixe the pipes you need to prime the pump. Undo the banjo at the output pipe, ask somebody to start the engine and when you get good flow there stop the engine, tighten the banjo partially back start the engine again and if you get activity in the tank tighten it fully back and top up the tank then go for a ride somewhere to drive it with many curves both ways as fast as you can to bleed the system then top up again if needed....if you cant get activity in the tank after priming the pump you'll have to replace it

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Thanks for your quick answer! I didn't drive without any liquid, but i drove some rounds around with the tank filled and the system like it is now: filled up but not working/not circulating. Right after finishing everything I drove around with a buddy, also with harder/faster corners and every once in a while opened the screw-connections at the rams (front and back) until fluid came out. Shouldn't that have done the same?

Edit: What do you mean by the banjo of the output pipe? Do you mean at the pump or the one connecting back to the fluid-tank, or at the valve-block?

DiscoveryCarl said:

What do you mean by the banjo of the output pipe? Do you mean at the pump or the one connecting back to the fluid-tank, or at the valve-block?

Click to expand...

The pressure pipe which goes from the pump to the block, the banjo on the pump aka the pump's outlet, as long as the pump was not primed there opening the rams is useless

sierrafery said:

The pressure pipe which goes from the pump to the block, the banjo on the pump aka the pump's outlet, as long as the pump was not primed there opening the rams is useless

Click to expand...

So i just tried it out. I undid the banjo directly below the pump completely and had my dad start the car. The tank was almost empty in under a second so I told him to stop immediately. I filled the tank back up completely and had him start the car again and immediately turn it off, so the pump doesn't have air inside anymore(because I was scared the pump sucked air again the first time, because the tank was almost completely empty). After that i reconnected the banjo again (only about something between half a turn or a full turn). Directly after having the banjo connected there is not more action inside the tank. Only very tiny bubbles that look a little like soda bubbles.
EDIT: I had the car running for like 10 minutes with the only a little tightened banjo, but no change at all...

Could there be something with the block? I'm pretty sure I have out and in connected correctly to the valve block, but I'm still not 100% sure. The pump is connected to the port with the high pressure filter witch is at the right side looking on to the connections of the valve block. So according to the image in the following link I should have the right connection as it is right now... Would be really nice if my pump is not broken


Thanks for your help so far!

This is a drawing that I did in paint, when looking to the valve block from the front. I hope you can understand how its meant. This is the right side of the following image:

DiscoveryCarl said:

EDIT: I had the car running for like 10 minutes with the only a little tightened banjo, but no change at all...

Click to expand...

Once the pump was well primed and it's OK then with the banjo partially undone it should have spilled fluid all over the place near the banjo, tighten the banjo back undo that feed pipe from the block attach to it a piece of garden hose long enoug to reach the tank, remove the cap, direct that pipe into te tank and start the engine, if the pump is OK you should get serious flow into the tank from that pipe and not be able stos top the flow with your finger, it's a bit messy but i dont see other way to 100% rule out the pump...if no flow or the pressure is low then the pump is fubar, if you have flow that way but no activity with everything connected then something esle is wrong

sierrafery said:

Once the pump was well primed and it's OK then with the banjo partially undone it should have spilled fluid all over the place near the banjo, tighten the banjo back undo that feed pipe from the block attach to it a piece of garden hose long enoug to reach the tank, remove the cap, direct that pipe into te tank and start the engine, if the pump is OK you should get serious flow into the tank from that pipe and not be able tos top the flow with your finger, it's a bit messy but i dont see other way to 100% rule out the pump...if no flow or the pressure is low then the pump is fubar, if you have flow that way but no activity with everything connected then something esle is wrong

Click to expand...

Thanks a lot for your answer. That sounds like a lot of work, but I guess I'll try it out tomorrow and give you an update.

sierrafery said:

Once the pump was well primed and it's OK then with the banjo partially undone it should have spilled fluid all over the place near the banjo, tighten the banjo back undo that feed pipe from the block attach to it a piece of garden hose long enoug to reach the tank, remove the cap, direct that pipe into te tank and start the engine, if the pump is OK you should get serious flow into the tank from that pipe and not be able stos top the flow with your finger, it's a bit messy but i dont see other way to 100% rule out the pump...if no flow or the pressure is low then the pump is fubar, if you have flow that way but no activity with everything connected then something esle is wrong

Click to expand...

Sooo...


This is the front right wheel housing, there I'm switchin from hydraulic hose to hydraulic pipes. So what I did is:

Instead of connection a garde hose I just connected Pump-Output-Hose directly to the Back-To-Tank-Hose, instead of feeding both into the valve-block. Sadly there is not a lot of turbulence/circulation visible in the tank. Almost the same amount as before... I have no idea how the pump could have gone fubar, as it worked until i dissected everything and I only turned the engine on after putting liquid in the tank. Could it be broken because i tried out a lot of times without ever priming the pump???

While doing the reconnection from the picture that i just described I didn't prime the pump again, as my PSF at home is out of stock. I'm going to buy another 5 liters on monday and maybe prime the pump again before doing the test again. But right now it looks like the pump is broken, from what you told me

Edit: There is some flow/circulation but it's not as visible/intense as inside the steering tank and i believe not as visible/intense as before all this, it's almost not visible at all.

DiscoveryCarl said:

Could it be broken because i tried out a lot of times without ever priming the pump???

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Yes, if you drove it with unprimed pump the pump has gone regardless that the tank was full...happened to me too long time ago when i knew nothing about D2s after a schmuck mechanic replaced a leaking hose and didnt prime the pump, i thought i need to plug in a diagnostic tool to clear the fault for the warning to go out so i drove it so but first time i checked the fluid in the tank was foaming then after my own research i realised the pump was dead and i kept learning about all the systems untill i ended up knowing RAVE by heart.... that's it, your pump is dead, now i'm sure

sierrafery said:

Yes, if you drove it with unprimed pump the pump has gone regardless that the tank was full...happened to me too long time ago when i knew nothing about D2s after a schmuck mechanic replaced a leaking hose and didnt prime the pump, i thought i need to plug in a diagnostic tool to clear the fault for the warning to go out so i drove it so but first time i checked the fluid in the tank was foaming then after my own research i realised the pump was dead and i kept learning about all the systems untill i ended up knowing RAVE by heart.... that's it, your pump is dead, now i'm sure

Click to expand...

Thanks a lot for your help, you're the first guy who can help me. I'll directly order a new pump. Do you know if I'm fine with getting a used one, or if not is a refurbished one fine? Or should it be a new one.

Thanks a lot man, now I know for sure.

Used but known good one would be fine, there are many on the market cos many owners are getting rid of the ACE only cos a pipe is leaking or other simple faults...just prime it well before you drive it, let the setup you made for test with the output directed to the return and you can test the replacement that way and if you move fast to reconnect the feed pipe to the block and the tank doesnt go empty the pump will be already primed...with a good pump you must see serious activity in the tank

sierrafery said:

Used but known good one would be fine, there are many on the market cos many owners are getting rid of the ACE only cos a pipe is leaking or other simple faults...just prime it well before you drive it

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Thanks a lot, I'll go and order one right now!

I would guess pump too.

I ought to get a spare just in case.

Hey guys,
so recently my used pump arrived from UK, after a longer delay of transportation and customs maybe. As sierrafery instruced (after mounting the pump into the car and putting the v-belt back in) I only connected the pumps intake to the tank and left the output free. After that I had my dad start the engine and we waited for the pump to get good flow. We waited about ten minutes without anything coming out of the pump... I just tried again alone running it another 5 minutes, level in the tank is not getting lower. Could it take like even more time??? Or could there be anything else wrong? I made a drawing before taking out the v-belt and also compared to a video on youtube. Also there are grooves and flats on the drive-disks where the belt goes on, so it's not even possible getting a wrong direction of spin... I'm pretty angry right now, because I'm pretty sure I got ripped of.

Hi, sorry to hear that. Something is not OK cos you should have a slight flow through the pump based on gravity too just that not enough pressure if it's not primed and it should be primed even by turning the pulley with your hand, starting the engine with outlet undone was my inovation to get it primed faster and avoid it's manipulation as in the book and worked for me every time. Isnt the outlet from the tank clogged or something? try to lift the tank a bit to increase gravity. Here's the official priming procedure

sierrafery said:

Hi, sorry to hear that. Something is not OK cos you should have a slight flow through the pump based on gravity too just that not enough pressure if it's not primed and it should be primed even by turning the pulley with your hand, starting the engine with outlet undone was my inovation to get it primed faster and avoid it's manipulation as in the book and worked for me every time. Isnt the outlet from the tank clogged or something? try to lift the tank a bit to increase gravity. Here's the official priming procedure
View attachment 282953

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So I took the hose off and the hose is not clogged... I tried turning the pump wheel by hand before putting the belt back on and restarting. There is a very very thin flow which will also drain the pump when turned off. I didn't connect the pump output to the tank directly as I did with my old pump. I didn't do that because I think the pump is not fully primed if there is not much flow, or am I wrong?

DiscoveryCarl said:

So I took the hose off and the hose is not clogged... I tried turning the pump wheel by hand before putting the belt back on and restarting. There is a very very thin flow which will also drain the pump when turned off. I didn't connect the pump output to the tank directly as I did with my old pump. I didn't do that because I think the pump is not fully primed if there is not much flow, or am I wrong?

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I cant add much to what i've already said in my previous post, i dont know how much flow should be with unturned pump cos i've always managed to prime the pump without much struggle so never needed to check that. Connect the outlet to the tank without fear and start the engine cos without backpressure there a good pump should be primed and get good flow in no time.

sierrafery said:

I cant add much to what i've already said in my previous post, i dont know how much flow should be with unturned pump cos i've always managed to prime the pump without much struggle so never needed to check that. Connect the outlet to the tank without fear and start the engine cos without backpressure there a good pump should be primed and get good flow in no time.

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So I did as you said and connected the pumps output to the tank as well(Banjo not fully put on). At first there wasn't much going on. Then I lifted the container, still not much going on. Then I started blowing into the tank with my mouth (I was desperate lol), then bubbles started coming and I repeated blowing into the tank until it made some weird pumping noises (can't describe it different) and now it's swirling inside. I uploaded a video: - here is the link, but it expires in one day. I am not sure if this is enough action, as the steering tank has much more going on.

This is still without the ACE-Block connected - just hose going from pump-output directly back to tank. I think I will try connecting the ACE Block as well (after getting some more PSF) and see if there are any errors when driving.

Fingers crossed, i dont know how it must be directly returned like you did cos i've never had to do that but let's see how it behaves with block connected too cos it seems a bit "lazy", i hope that your saga has ended even though it's very suspect that you had to struggle so much to prime that pump