When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I went ahead and removed the driver's side knee panel and there to the left of the steering column is the relay panel. See pic below.
The upper relay 214 is the ABS pump. Both relays are working fine. I then checked to see if power was getting to the pump and here I discovered an error in the Bentley wiring diagram (see 2nd pic). The Grey wire leaving the relay from 87 does NOT go to terminal 13 on the ABS controller under the hood. This would be obvious by seeing that if you followed the diagram, the color of the wire has mysteriously changed from grey to brown! In the diagram the square 42 should read 39 and go to terminal 14 at the ABS multi pin connector under the hood. Anyway . . .
Applying 12v to the grey wire (or even to the relay #87 terminal) made the pump start very weakly. Sometimes the pump would not start, but when I gave it a thwack on the side it would rumble off again. So my conclusion is that the pump is failing and giving the P00301 error. Anyone know if just the pump can be removed from underneath the ABS unit? Or if the pump can be removed without opening up the brake fluid lines and have to go thru all the brake bleeding?
I have the same issue on my S8 when applying hard on brakes the ABS works for a second then the ABS and ESP light come on. the fault is" 00301 Return Flow Pump V39"
I shut the engine off for a second start the engine the Lights goes off the ABS pump spins (hear sound).then if you need to apply hard on brakes or need the traction control to interfere the same issue happens. I don't think is the relay because it is working at the beginning then failing after using ABS or ESP. and can you tell me how to remove the pump under the ABS module . my car is a Prefacelift Audi S8 .
My car is a 2002 USA S8 so I don't know how it compares to yours but here's what I did:
Being pretty sure it was a pump problem, I wanted to lift the whole ABS unit up to access underneath it and just detach the pump so I didn't have to disconnect the brake lines and bleed the brakes. This wasn't possible.
I bought a replacement ABS unit on Ebay that came out of a Passat intending to swap in the whole unit. Unfortunately, although the numbers were the same, the electrical connector was different so I had to keep my silver box part and just use the Passat pump.
I disconnected all the brake lines going into the unit. Make sure you have something to cap all the ends quickly, or else you'll have brake fluid all over the place. Undo the 2 nuts that hold the unit in place. Disconnect the electrical connector and pull the unit out. I then blocked all the holes to try and keep as much fluid in the unit as possible. (finding appropriate caps was hard!) I turned the unit over and detached the pump. I can't remember if it was screws or bolts. The pump just pulls out and it doesn't have any connection with the unit's internal brake fluid passages. Unfortunately electrically the pump wasn't a simple plug in, so I cut the wires and spliced in the Passat one, wrapping the joins with liquid tape.
(You might want to send 12v to the new pump to make sure it runs OK first)
I then re-assembled everything and bled the brakes. If you have VAGCOM there's an option where it goes thru and exercises all the ABS brake functions. I ran that a couple of times, bled the brakes and the error code was fixed and I had normal brakes.
My car is a 2002 USA S8 so I don't know how it compares to yours but here's what I did:
Being pretty sure it was a pump problem, I wanted to lift the whole ABS unit up to access underneath it and just detach the pump so I didn't have to disconnect the brake lines and bleed the brakes. This wasn't possible.
I bought a replacement ABS unit on Ebay that came out of a Passat intending to swap in the whole unit. Unfortunately, although the numbers were the same, the electrical connector was different so I had to keep my silver box part and just use the Passat pump.
I disconnected all the brake lines going into the unit. Make sure you have something to cap all the ends quickly, or else you'll have brake fluid all over the place. Undo the 2 nuts that hold the unit in place. Disconnect the electrical connector and pull the unit out. I then blocked all the holes to try and keep as much fluid in the unit as possible. (finding appropriate caps was hard!) I turned the unit over and detached the pump. I can't remember if it was screws or bolts. The pump just pulls out and it doesn't have any connection with the unit's internal brake fluid passages. Unfortunately electrically the pump wasn't a simple plug in, so I cut the wires and spliced in the Passat one, wrapping the joins with liquid tape.
(You might want to send 12v to the new pump to make sure it runs OK first)
I then re-assembled everything and bled the brakes. If you have VAGCOM there's an option where it goes thru and exercises all the ABS brake functions. I ran that a couple of times, bled the brakes and the error code was fixed and I had normal brakes.
I have the same error code and will be tackling this job real soon. Any advice not already mentioned in the thread?
I would rather not buy a used part as it will likely have the same issue in the future.
If it is then I will be happy I can get it fixed. Not terribly happy about having to disconnect all the brake lines but feel it is necessary to have fully functioning ABS and ESP... these are the things I bought the car for...along with the AWD and v8.
If it is then I will be happy I can get it fixed. Not terribly happy about having to disconnect all the brake lines but feel it is necessary to have fully functioning ABS and ESP... these are the things I bout the car for...along with the AWD and v8.
I would just get a used pump from a wrecking yard..
I would just get a used pump from a wrecking yard..
But wouldn't a used one have the same flaw as the one already in my car? If I have to pull the whole unit anyway, I would think that replacing it with the original one that came out of the car (that was repaired) rather than a unknown from a junk yard (that may need to be coded to work in mine) would be the best option.....yeah the car will be immobile for a while due to the trip to and from the UK....But whatever.
There's no coding involved (This is not a Volvo!!
The pump part is simply an electrical motor that wears out.
I used one that came from a VW Passat.
Obviously it's better to have one from a lower mileage car.
Sure, there's a risk, but when I got mine, I put it on the bench and gave it 12v and made sure it consistently span up strongly.
Do the same with your bad one and you'll soon see the difference. The bad one takes a while to start spinning, (if at all) and then limps along.
01-18-2015, 04:14 AM
