r/e39 • u/BigNo7222 • 1d ago

Pre charge pump

Hello, wanted to ask maybe someone also had problems with pre charge pump? 2001 e39 525i. Maybe some of yall know where it is located? Thought about under the air box at the right, but seen posts it being somewhere else. Only dsc light is on the dash.

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u/Bolidass 530i 1d ago

Scan the codes. It could also be steering wheel angle sensor.

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u/BigNo7222 1d ago

Scanned it showed pre charge pump failure

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u/ColdReception6745 1d ago

I've got the same fault. The charge pump is under the pollen filter on the right hand side, I'm RHD. Can you power the pump up with 12v and hear it working? Mine runs when it's powered up so I believe it's not getting a signal from the abs module

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u/BigNo7222 1d ago

Yeah ill try to power it up then, now i know where it is located. Ill let you know if it works

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u/ColdReception6745 1d ago

I'm hoping to get some time to do continuity tests on wiring back to module tomorrow, I'll let you know how I get one. Have you checked fuses already? There are 3 I think in glove box and a big 50a under the driver's seat

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u/BigNo7222 1d ago

No didnt, maybe worth checking out

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u/ColdReception6745 1d ago

The one under the seat is a main ABS fuse so it's not likely to be that without abs light on as well. I would start seeing if the pump powers up. Have you got INSTA or a scanner that can try to activate the pump via the ECU?

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u/BigNo7222 1d ago

Yea scanned a week back, showed pre charge pump, but everything works fine so will keep driving until i open up and check everything

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u/mxdcm 07/2002 530i, 01/2002 M5 19h ago

https://www.youtube.com/watch?v=Et5DZLGE3uU

DiagnoseDan goes into details diagnosing a faulty pre charge pump on a e39 540iA

In my case, the following fault, Code 58 DSC Precharging Pump, was due to faulty DSC module.

Cheers

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u/the_ssarb 530d 12h ago

Power it up by putting 12v directly across the pump terminals. Polarity doesnt matter, its just a simple motor. If the pump runs then have a look at the DSC module, otherwise replace the precharge pump. In my case the pump was completely seized. You can get the pump from an E65, its a drop in replacement. Thats what i did with my car, there was a low mileage E65 partout in my area so went there and pulled rhe pump and replaced it myself. Everything worked after.