Volvo XC70 This wagon/SUV crossover offers the capabilities of an SUV without SUV size.

ABS Computer problem??

  #1  
Old 08-26-2008, 11:50 AM
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Default ABS Computer problem??

I'm getting the following codes:
P0571 - Brake switch A circuit malfunction
P0504 - Brake switch A Brake switch B Correlation
Is this an ABS computer problem? Brakes work fine. Cruise, trip computer, etc don't work - all kinds of warning lights are lit
Dealer thinks it is the computer
Anybody seen this?
Is there a cheaper place to get a computer ($1000.00 dealer list probably)
Thanks
 
  #2  
Old 08-26-2008, 01:42 PM
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Default RE: ABS Computer problem??

Welcome to the forum.

What year and engine for the vehicle?

P0571 relates to Volvo code ECM9400 which is either a faulty signal or a missing signal from the brake pedal sensor. Symptoms are cruise control not working and brake light continuously on.

Check for problems in the brake control module and the central electronic module. Also check for bad/dirty contacts between the engine control module and the brake light switch; open circuit in the voltage feed to the brake light switch; open circuit or short circuit in the cable to the brake light switch; incorrectly installed brake light switch; incorrectly adjusted brake light switch or damaged brake light switch.

I can't find a Volvo code relating to P0504.
 
  #3  
Old 08-26-2008, 07:15 PM
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Default RE: ABS Computer problem??

Did the Dealer pull the codes?
I have never seen a Dealer us P codes.
 
  #4  
Old 08-27-2008, 06:40 AM
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Default RE: ABS Computer problem??

Car is 2002 XC70 not sure on the engine code - I'll check.
The codes came from my code reader.
The dealer told me their code reader saw ABS issues.
As I understand it 2002 and new ABS modules can not be rebuilt.

Thanks for the replies
 
  #5  
Old 08-27-2008, 06:38 PM
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Did you check the places that rebuild them yourself?
The 2003 or 2004 are the newer different style.

 
  #6  
Old 12-04-2009, 05:46 PM
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Default ABS ECU ISSUES P0571 and P0504

I'm having same problem on 2002 s60 AWD. I got the same p-codes, same behavior. Please let me know if you were able to fix your vehicle.

P0571 - Brake switch A circuit malfunction
P0504 - Brake switch A Brake switch B Correlation
Brakes work fine. (Cruise, trip computer, traction don't work)

Thanks,
 

Last edited by volvo2002; 12-04-2009 at 05:52 PM.
  #7  
Old 12-04-2009, 09:26 PM
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Originally Posted by volvo2002 View Post
I'm having same problem on 2002 s60 AWD. I got the same p-codes, same behavior. Please let me know if you were able to fix your vehicle.

P0571 - Brake switch A circuit malfunction
P0504 - Brake switch A Brake switch B Correlation
Brakes work fine. (Cruise, trip computer, traction don't work)

Thanks,
Sounds like the common bad ABS module.
 
  #8  
Old 12-11-2009, 07:50 PM
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Originally Posted by tech View Post
Sounds like the common bad ABS module.

Got this same issue this week. When you turn off and turn on engine the warning will go away. Until it came to a point where the message stayed (Engine System Service Required) and amber triangle is on. Odometer is also screwed up (shows dashes only) and cruise control too.

I was able to pull down P0571 code and also was able reset/erase it.

I put a new brake position sensor today but problem still persists.

It feels like there is really nothing wrong with the car except for the code. Is it safe to assume that it is still OK to drive the car in its condition when the warning message is up ?

I dread that this is a BCM failure. It costs around a grand in this MY (04) of the S60

Any ideas will be much appreciated. Also thinking of taking it to the dealer for full diagnostic.
 
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Old 12-11-2009, 09:58 PM
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Originally Posted by redz1006 View Post
Got this same issue this week. When you turn off and turn on engine the warning will go away. Until it came to a point where the message stayed (Engine System Service Required) and amber triangle is on. Odometer is also screwed up (shows dashes only) and cruise control too.

I was able to pull down P0571 code and also was able reset/erase it.

I put a new brake position sensor today but problem still persists.

It feels like there is really nothing wrong with the car except for the code. Is it safe to assume that it is still OK to drive the car in its condition when the warning message is up ?

I dread that this is a BCM failure. It costs around a grand in this MY (04) of the S60

Any ideas will be much appreciated. Also thinking of taking it to the dealer for full diagnostic.
Your might be the brake pedal sensor.
 
  #10  
Old 12-13-2009, 04:40 PM
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ECM 9400 is usually the brake pedal sensor in the booster (not on the pedal itself). Ive seen some rebuilt BCMs but the cost is almost the same and usually contain less of a warranty.
 
  #11  
Old 12-14-2009, 11:07 AM
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Originally Posted by deucetech View Post
ECM 9400 is usually the brake pedal sensor in the booster (not on the pedal itself). Ive seen some rebuilt BCMs but the cost is almost the same and usually contain less of a warranty.

Took the car to the dealer to get Volvo specific codes pulled. I held off on replacing the brake pedal sensor. I did replace the brake position sensor but that obviously did not fix the problem.

Will give un update maybe later today when I get the exact volvo codes.
 
  #12  
Old 12-14-2009, 02:17 PM
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Originally Posted by redz1006 View Post
Took the car to the dealer to get Volvo specific codes pulled. I held off on replacing the brake pedal sensor. I did replace the brake position sensor but that obviously did not fix the problem.

Will give un update maybe later today when I get the exact volvo codes.

Got the codes back.
Still pretty generic and all seem to point to bad BCM

ECM-9400 Brake control module (BCM). Faulty signal
ECM-9400 Brake pedal position sensor, faulty signal.
BCM-0052 Control module. Internal fault
CEM-1A5F Communication with the ABS control module. Signal missing. Intermittent fault


Dealer quoted $1800+ to replace and reprogram
 
  #13  
Old 12-15-2009, 08:54 PM
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WOW that is alot!
 
  #14  
Old 12-16-2009, 10:00 AM
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Originally Posted by tech View Post
WOW that is alot!

Yeah. So I'll be driving without ABS for a while

The BCM for our MY(I think starting from 02) cannot be rebuilt and it will require reprogramming if I get a new one or a salvage part.

Might try and find an indy or specialist shop around here that would do it for less.
 
  #15  
Old 12-16-2009, 07:15 PM
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If you can find a used one cheap give it a try. I think a few years ago we changed out a used module in a car and it was fine.
 
  #16  
Old 02-02-2013, 02:00 PM
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Default ABS works until driven at 35mph

My 2002 XC70 ABS suddenly stopped working. CEL pointed to wheel sensors, replaced the one that was marginal based on ohm resistance reading. Problem persisted, so pulled module and sent it to Midwest Modules for a diagnosis. The mod checked out fine, but he was able to pull two codes, low voltage and pedal position sensor. Since the unit didn't need to be cracked open, he charged me a very reasonable fee for his excellent and super fast service. I'm going to replace the switch from FCP Groton, however they do not show the switch available for the 2002 xc 70. Does anyone know if it is the same switch as the 2002 v70, which FCP has for around $110?

If you do pull your module, it is better to have it repaired... As replacements require costly reprogramming to match to your 2002 or newer Volvo. Midwest Modules provided exceptional service and guidance, I highly recommend them.

When pulling your module, the wiring harness requires that the housing be slid back to release the plug. It is highly recommended that you disconnect the battery and not drive the car with the module out.

Note: codes stored in the ABS module can not be pulled from your typical OBD2 code reader.
 
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