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steve30

Error code 88 - ABS precharge pump, need some help/advice!

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Hi,

I've been having the usual problems with my DSC/ABS lights on for a while now, although for the last couple of weeks the DSC light has been on permanently.

I had the codes read today and it is showing code 88 - precharge pump.

Not heard of this one! Any suggestions?

Is this likely to be a case of the module failing or is it likely there is a problem with the pump?

Cheers for all your help and advice!

Steve

Edited by steve30

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Just bringing this back up as I have the same error. Had DSC, brake and ABS lights pop on yesterday but after next restart was only DSC light.

 

Error is 88 precharge pump in INPA. Funny thing is it says vehicle speed 2.57 km/h but I was sitting stationary on the drive??

 

Did you get this sorted, Steve?

 

Anyone else had this before. Would investigate further but I keep forgetting my lights are always switched on when I'm sitting inside playing with INPA so I now have a flat battery! Grrrr

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Interior lights can be "permanently" disabled by pressing and holding main interior light switch for a few seconds. I always do this if in and out out car, even when vac'ing it out. Just repeat to enable automatic mode when all done.

Also, on the Touring, if the tailgate is going to be open for any length of time I close the tailgate catch with my fingers to turn off the light on the tailgate.

Ask me why .........:)

Sent from my iPad using Tapatalk HD

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Thanks that's a handy tip given how often I'm playing around in the car with the engine off.

 

Wont help me if I keep leaving the headlight switch on though! :(

 

So nobody knows owt about precharge pumps then? :(

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From WDS: CLICK

 

I would say 9 out of 10 cases faulty DSC module causes this. The pump itself fails quite rarely. You can test the pump with direct voltage (black/green = positive, black/brown = ground).

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Thanks for that. Have been looking in WDS myself too. Precharge pump doesn't seem to be where WDS says it should be though. Will have to go have another look and if I find it give it a test.

 

I see in INPA it looks like you can activate it from there too, but there's actually two 'preload pumps' you can activate (along with a plain 'pump'). I wonder which one is the precharge pump and what the other one is. Hmmmmmmmmmmm...

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Hi

 

Did you ever get this issue sorted? I have the same problem, and have drawn a blank with rebuilt ECU's and trips to BMW.

 

The DSC Precharge pump is working correctly, and so apparently is the ECU. BMW even kindly swapped a known working precharge pump with mine to test, and got exactly the same error. The ECU was rebuilt and programmed to my car both at the ECU place and at BMW, still the same result. Error 88 Precharge pump. The ABS is functioning correctly and always has.

 

Whats so frustrating about this is all its for is to switch the DSC light off so I can get an MOT on it! 3 months off the road and all I want to do is scrap the car and buy another one ....

 

Paul

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Hi there,

 

Not yet but almost hopefully! See this thread...

 

http://forum.bmw5.co.uk/topic/111199-new-or-rebuilt-abs-module/

 

I could see what wires were broken in mine and attempted to fix (but it is nigh on impossible). I actually had it so I could run the precharge pump through INPA so seemed to be working, but the error code still wouldn't clear - made no sense.

 

So I thought feck it replace the module. Went for a new one as hardly much more than a rebuilt and I've heard it's hit and miss whether rebuilding can actually fix the problem (possibly the problem you are now experiencing?).

 

It's currently stuck in customs somewhere, so I'll update in that thread when I've fit and coded the new module.

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P.S. have you considered bulb removal? :) I mean a proper tester should check for ABS light to come on then go out so you shouldn't be able to fool them on that one, but a DSC light? Will they even be looking?

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Unfortunately the MOT test requires the light to work in the correct order, ie: on, start car, off. Without that sequence its a fail :( 

 

The ABS light works the same way and same sequence, and as there is nothing wrong with the ABS,  I feel a re wire coming on, switched so I can continue to work on the fix....

 

Its not even like I even use/like/want the DSC part!

 

I'll have a read of the thread linked, thanks for that :)

 

Paul

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What I was getting at was will the tester even be looking for the DSC light to come on and go out? ABS light I would expect them to check, but DSC? Many cars don't even have a 'DSC' light to come on and go out.

 

Was just a thought - not sure if it would work - been out of the UK for 4 years :)

 

Anyway - good luck. I'll update when I finally get my new module...

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Yeah they specifically check that one too. They now have a list of these things for each model, and have to observe. A real pain for something that is actually pretty useless. (DSC)

 

I should be getting my unit back end of week hopefully, as its about the 5th time of attempted repair, they are waiting on a new unit to test it against, before sending it back.

 

My ECU sends the start signal to the precomp pump, which does its test start bit (and as I mentioned, this works the same as a new unit) it just doesnt acknowledge that its own signal was succesfull and errors.

 

I have given up holding out hope that it will actually work, but will see. I may get a supprise after all this time.

 

Paul

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Oh right tricky buggers!

 

Sounds very similar to how mine behaved after my repair attempt (before it decided to revert back to not being able to run the precharge pump at all, and throwing a wheel sensor error for good measure!).

 

I hope yours works this time - although I've read some just can't be repaired. Hope someone is footing the bill for you for all these rebuild attempts! For less than 300 quid I just thought not worth the risk I'll just get a new module.

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I had this... it was my battery, new battery sorted it... i had an original 12 year old battery in there. Although, I was seeing other issues such as not being able to start after several short runs.

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Paul - fyi, i updated my thread linked above.

 

My new unit is in and coded, steering angle sensor initialised, now all working, lights out, no error codes. :)

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Yeah they specifically check that one too. They now have a list of these things for each model, and have to observe. A real pain for something that is actually pretty useless. (DSC)

 

I should be getting my unit back end of week hopefully, as its about the 5th time of attempted repair, they are waiting on a new unit to test it against, before sending it back.

 

My ECU sends the start signal to the precomp pump, which does its test start bit (and as I mentioned, this works the same as a new unit) it just doesnt acknowledge that its own signal was succesfull and errors.

 

I have given up holding out hope that it will actually work, but will see. I may get a supprise after all this time.

 

Paul

In my last 525d I had the passenger airbag light blanked out for 5 different mots and re-tests (different reasons) and never failed on it once as the tester never noticed. 

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Liam, thats good :)

 

My unit came back yesterday, (yet another one ... 5 now) and as the car has been with local BMW for 3 weeks, I gave it to them to fit and test again. Waiting for verdict.  (I have no confidence it will be any different to the others)

 

Evil: My MOT mad checked them all for correct operation and sequence! :(

 

Stan: That will only happen if your battery is putting out such a low voltage that the electronics wont fire (10v I think), my sons M3 did the same on a dead alternator, we watched the battery voltage drop from test mode on the computer, and when it dropped into the 9's various modules cut out. This isnt the case with these ones. 

 

:twiddling thumbs while waiting for news on latest module :)

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When you say you have tried 5 units - you mean tried to get your old one rebuilt 5 times? Or tried 5 rebuilt units? Or have you tried a new one and still not been successful?

 

As I said I think my success might be to do with going for a new module instead of trying to get my old one rebuilt. Everything just went 'as it should' when I knew what I was doing, whereas my own attempt to repair my unit (admittedly not a pro job but it looked like I had reconnected the broken wires) seemed to work, i.e. it ran the precharge pump, but still wouldn't clear the error, which seems to be how yours behaved from your description.

 

Hopefully this one is ok!

 

Good luck with it :)

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Todays update ...

 

Last week I got the latest ECU back (5 different ones total now) and gave it to my friendly BMW dealer tech, who have had the car for 4 weeks while the last few failed ECU 'rebuilds' have taken place...

 

He plugged it in as normal, and this one behaved differently to the other 4 in that when switched on, the dashboard lights went through what looked like an extended check and re program. Started car, reset the steering angle sensor, and for the first time in a Loooooong time, the DSC light went off :) 

 

It has stayed off ever since! this is despite the car having the same components on that the ECU rebuilding company told me must be at fault as their unit was perfect .... what a load of tripe! got caught out on it this time, as we were able to prove that all the mentioned components were in perfect order, including swapping some out for known working or new items to show that they were not at fault. I am really grateful to the head tech at this BMW dealer for the effort he put into helping sort this, alongside trying hard to keep my costs down, for what he realised was a real piece of bad luck and mis information from the rebuild company. This SHOULD have been a simple replacement, with a properly rebuilt unit like the 5th one was. 

 

I know that they got this last unit in from elsewhere, so I assume A) it was a blank unit, wiped clean of all previous coding (hence the light sequence reprogramming on initial start) and B) it had been rebuilt and tested properly unlike the previous 4.

 

Anyway, I have a car back with an MOT 4 1/2 months after it first failed its MOT. Its been a bloody nightmare, heavily compounded by the problems caused by the rebuild company. Now for the fun bit ....

 

I never did get to try out the other software Liam, was too scared to touch it until I had that MOT in my hands :) 

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Hey - glad it's now sorted finally! I hope you are not ending up out of pocket.

 

Not such a bad thing they coded it for you so you avoided having to learn and use NCSExpert! :)

 

It's further indication of what I read before - that a rebuild is always a gamble. Not sure how much a rebuild costs, but with a new unit less than 300 it seems worth the extra.

 

Seems like the rebuild just replaces all those thin wires and runs a test program. Looks like it wouldn't cover any faults in the controller chip itself if there were any, and that it's possible the test program can pass even if some faults remain. I've seen the error of the precharge pump running fine but that error code not being able to be cleared a few times now - with you, myself and reading on the net.

 

Just glad you got it sorted!

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This pre-charge problem is something these refurbishers usually can't repair properly. Also it must be noted that if the ground wires have been broken for a longer time other components on the board may have taken damage and the unit can't be repaired by simply renewing the broken wirings.

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Yeah good point, although you would think the test program would identify if anything is still wrong, but it seems not always. Glad I went with a new unit and that would be my recommendation to anyone else with this precharge pump error.

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I would also say go down the new route too, after all, whats the point of getting a unit refurbished if it only ends up 90% and doesnt actually fix the issue that its been sent off for in the first place!

 

The first 4 apparently tested good. They weren't. This is clearly a problem where the test equipment doesnt test the units 100% which is pretty useless really.

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Actually, got a question about NCSExpert, does it have the ability to trigger the ABS in order to clear air out of the brake manifold block? BMW have this as a tool on their software, and as I was incorrectly told to remove and send back the whole block (ABS pump, manifold and ECU) I have to do the to properly bleed the brakes. At the moment, they work, but with a long pedal. I used my pressure bleeder, which does everything from manifold to calipers well, but wont remove the valve air.

 

I cant find this option on carsoft 6.5, and havent loaded any other software up yet.

 

I will post this same thing in the main part of the forum later too, as there must be a way to work this without going to BMW again.

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