Author Topic: ABS - Pressure sensor, control circuit  (Read 5098 times)

Roy_F

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ABS - Pressure sensor, control circuit
« on: August 09, 2022, 01:14:17 PM »
Hi Guys, on my 2011 BMW K1600GT, I had the ABS warning light come on at start up and hasn't gone off (DSC light works as normal and goes out when moving).

Brake light works fine from both hand and foot brake and ABS appears to still work, certainly with the rear brake. Speedo is working but Cruise Control isn't but this  was until the warning light came up.

I've plugged the GS-911 in and its showing an error of -  0x480A0B  -  Pressure sensor, control circuit, front, p2T time interval

Squeezing the right hand brake lever, pressure raises in wheel circuit front, but control circuit front remains at 0.0. However if I do the same with the rear brake, the  wheel circuit rises as expected and so does the rear control circuit (from around 6.7 PSI static upwards).

I've plugged a spare ABS unit into the ABS ECU (not plumbed in) both control circuits come up 0.0 psi as I would expect, but still the same error  0x480A0B  -  Pressure sensor, control circuit, front, p2T time interval.....

Any advice or pointers would be greatfully received.....Thank You.

Cheers, Roy............

Ruan

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Re: ABS - Pressure sensor, control circuit
« Reply #1 on: August 10, 2022, 03:25:26 PM »
Hi Roy

You've basically ran through the troubleshooting suggested by the handbook, just to confirm, did you give a small test ride with the replacement ECU installed?

Kind regards
Ruan

Roy_F

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Re: ABS - Pressure sensor, control circuit
« Reply #2 on: August 10, 2022, 04:10:45 PM »
Hi Karma,

Thanks for your reply, it was a replacement ABS Pump/Valve unit I tried as I had a spare one of these but I didn't have a spare ECU unit that bolts onto it. I couldn't do a test ride without swapping the Pump unit on the bike and draining / bleeding the circuits, so I just connected it to the ECU dry to the side of the bike.

With the spare Pump/Valve connected to the original ECU (out of the bike) and no fluid in it, I had 0.0 bar of pressure in both control circuits front and rear as expected, but still had the same error "Pressure sensor, control circuit, front, p2T time interval", I didn't have an error showing for the rear control circuit so exactly the same error was seen with this different Pump/Valve unit.

I did try covering the Front Control Circuit contacts on the ABS Pump/Valve unit with a small piece of paper (second from left with contacts at the top), which this time gave " Front control Circuit Electrical Error" or something similar, so it looks like I have good electrical connection with the the Pump/Valve unit.

With the same fault showing with both Pump/Valve units, I think I have eliminated the Pressure sensor and electrical connection to it with the fault likely being in the ECU.....???

I have another ECU arriving tomorrow off of exactly the same age of bike, so I'm hoping this will clear the fault as all wiring looks good....

I'll let you know how I get on... unless I have missed something obvious....???.....Always open to any suggestions which are greatfully received......

Cheers Karma,

Regards, Roy.

Ruan

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Re: ABS - Pressure sensor, control circuit
« Reply #3 on: August 10, 2022, 04:47:34 PM »
Hi Roy

I see, no, the service plan pretty much states, if the fault occurs repeatedly or is currently present, replace the ECU...

You can check this out from a site Schuppi posted a while back below:
https://bmwfault.codes/

Just remove the 0x before the fault code.

Kind regards
Ruan

Roy_F

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Re: ABS - Pressure sensor, control circuit
« Reply #4 on: August 10, 2022, 05:03:02 PM »
Sincere apologies Ruan,  and my mistake,  for addressing you as 'Karma' earlier....

Thanks for the mail and the added detail, that's a very useful site.... Im pleased to see I've hopefully covered off all the basics and everything is still pointing towards the ABS ECU. Hopefully the replacement will be here in the morning, so I'll connect it up and see if the fault clears. I'll let you know either way of course.....

Many Thanks,

Best Regards,

Roy.

Roy_F

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Re: ABS - Pressure sensor, control circuit
« Reply #5 on: August 13, 2022, 11:52:35 AM »
Hi Ruan,

Just to close this one off......

The replacement ABS Pump / Valve Block / ECU unit arrived yesterday. I removed just the ECU and swapped it out with the ECU on my K1600 and the error message cleared. Under 'Real-time Values' both front and rear Pressure Control Circuits came up with around 6.7 PSI. Before, the Front Control Circuit was reading 0.0 PSI and never changed. So the ECU fixed the problem.

By changing just the ECU I did not need to remove the pump assembly from the bike and so avoided having to drain, refill and bleed the fluid etc. Once the side panel was off there was just enough room to undo the four ECU securing screws and remove it from the pump.

Thanks again for your help,

Best Regards,

Roy.