2005 S80 2.5L petrol, p0503 fault code

clpratt · Sep 15th, 2016, 22:05

Hi, I am having problems on my 2005 S80 2.5L. I have occasional ABS, brake warnings, message -Brake failure, stop safely-, frozen mileometer and odometer. Diagnostics shows code p0503 VSS output low/intermittent. Where is the vehicle speed sensor please, and how do I access it.

Chris_Rogers · Sep 16th, 2016, 13:59

Vehicle speed signal comes from the ABS (BCM Module) which seems to be the area causing a problem.

You will need to get the codes read from this with a Volvo specific scan tool.

clpratt · Sep 17th, 2016, 11:07

Thanks Chris for your reply. I have previously removed the ABS module resoldered all connector plug joints to the circuit board, reinstalled module. This made no difference. Incidentally the reported Fault code was Vehicle Speed Sensor A, that suggests there may be others i.e. VSS B etc. Somewhere I saw a suggestion that the VSS sensor may on the output end of the engine so I temporarily disconnected 2 sensors I found there but that just created "Transmission" error messages. Not having very easy access around the engine I wondered if anyone knew the specific location of this sensor. Elsewhere it's also been suggested that the front wheel sensors and pulse rings may be at fault. When I next get the car on the drive I shall check these out. I will be grateful for any more ideas.

cheshired5 · Sep 17th, 2016, 11:16

Start with the simple stuff https://www.youtube.com/watch?v=77sntnVpyvI

Chris_Rogers · Sep 17th, 2016, 12:15

You are reading a generic OBDII code from the engine management system.

On your car the speed sensor signal to the engine management system is derived from the ABS system and sent to the engine management ECU as a digital message via the CAN network.

There are no other speed sensors involved other than those associated with the ABS system.

The quickest way to diagnose the fault will be to have the Volvo specific fault codes read from the ABS system, which a generic OBDII code reader won't do.

V70Zig · Sep 17th, 2016, 13:58

Lot's of members have Vida Dice which will read the ABS.......so give a shout out for someone in your area that has it....for a "proper" read and diagnosis.
Saves going round in circles...cost, maybe free or a few beer tokens.
Worth a shout though.

Sep 15th, 2016, 22:05	#1
clpratt New Member Last Online: May 10th, 2018 09:04 Join Date: Dec 2006 Location: Reading	2005 S80 2.5L petrol, p0503 fault code Hi, I am having problems on my 2005 S80 2.5L. I have occasional ABS, brake warnings, message -Brake failure, stop safely-, frozen mileometer and odometer. Diagnostics shows code p0503 VSS output low/intermittent. Where is the vehicle speed sensor please, and how do I access it.

Sep 17th, 2016, 11:16	#4
cheshired5 Premier Member Last Online: Dec 26th, 2021 13:42 Join Date: Dec 2013 Location: Crewe	Start with the simple stuff https://www.youtube.com/watch?v=77sntnVpyvI __________________ 2002 S60 SE D5 Manual 209000 miles

Sep 17th, 2016, 13:58	#6
V70Zig Master Member Last Online: May 20th, 2024 14:18 Join Date: Sep 2012 Location: Loughborough	Lot's of members have Vida Dice which will read the ABS.......so give a shout out for someone in your area that has it....for a "proper" read and diagnosis. Saves going round in circles...cost, maybe free or a few beer tokens. Worth a shout though. __________________ 2008 V70 SE D5 Auto 185 ...now 205 Volvo Polestar......190k Passed away - 1999 V70 2.5tdi Auto 340632 miles, RIP.

Sep 16th, 2016, 13:59	#2
Chris_Rogers VOC Member Last Online: Apr 10th, 2017 16:55 Join Date: Jan 1970 Location: South Kent Coast	Vehicle speed signal comes from the ABS (BCM Module) which seems to be the area causing a problem. You will need to get the codes read from this with a Volvo specific scan tool.

Sep 17th, 2016, 11:07	#3
clpratt New Member Last Online: May 10th, 2018 09:04 Join Date: Dec 2006 Location: Reading	Thanks Chris for your reply. I have previously removed the ABS module resoldered all connector plug joints to the circuit board, reinstalled module. This made no difference. Incidentally the reported Fault code was Vehicle Speed Sensor A, that suggests there may be others i.e. VSS B etc. Somewhere I saw a suggestion that the VSS sensor may on the output end of the engine so I temporarily disconnected 2 sensors I found there but that just created "Transmission" error messages. Not having very easy access around the engine I wondered if anyone knew the specific location of this sensor. Elsewhere it's also been suggested that the front wheel sensors and pulse rings may be at fault. When I next get the car on the drive I shall check these out. I will be grateful for any more ideas.

Sep 17th, 2016, 12:15	#5
Chris_Rogers VOC Member Last Online: Apr 10th, 2017 16:55 Join Date: Jan 1970 Location: South Kent Coast	You are reading a generic OBDII code from the engine management system. On your car the speed sensor signal to the engine management system is derived from the ABS system and sent to the engine management ECU as a digital message via the CAN network. There are no other speed sensors involved other than those associated with the ABS system. The quickest way to diagnose the fault will be to have the Volvo specific fault codes read from the ABS system, which a generic OBDII code reader won't do.

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