ABS Pump or Controller on scanned 850 ?

laser · Post by **laser** » 04 Feb 2024, 17:43

What is most likely, cracks in the soldering on the ABS control unit on the 850 or ABS pump?

Have managed to get 3 error codes on Volvo 850 -96 via OBDII (ELM327)
ABS-313 LRear wheel sensor open/short
ABS-314 RRear wheel sensor open/short
ABS-443 Pump motor fault

I don't want to disassemble the control unit in sheet metal if there is a fault with the ABS pump, without the 443 fault I would have been more sure of only the wrong control unit.

xanthefin · Post by **xanthefin** » 04 Feb 2024, 18:19

For Control Unit my voice at least.
Pump has larger power connecter which solders just goes absolute horrible condition after aging and thermal plus vibration cycles if not yet ever opened and fixed.

I seen personally multiple times pump code with cracked abs units on 850 along with sensor codes.

jmartin919 · Post by **jmartin919** » 04 Feb 2024, 19:33

I was commenting to another poster that the ABS on my '93 makes a very brief scrapping sound shortly after starting up and driving but works fine and gives me no codes, You mention the condition of the solder joints in the control unit and it got me to wondering if maybe the scrapping I'm hearing is the pump not getting the full current it needs due to weak solder joints. The control unit is original with about 200K on it.

Post by **foggydogg** » 04 Feb 2024, 22:21

Pumps rarely fail, cold solder joints on the control unit are a sure thing.

Post by **abscate** » 05 Feb 2024, 04:47

jmartin919 wrote: 04 Feb 2024, 19:33 I was commenting to another poster that the ABS on my '93 makes a very brief scrapping sound shortly after starting up and driving but works fine and gives me no codes, You mention the condition of the solder joints in the control unit and it got me to wondering if maybe the scrapping I'm hearing is the pump not getting the full current it needs due to weak solder joints. The control unit is original with about 200K on it.

If it is a brief sound at 10-15 mph on first acceleration after key off, that’s the normal system self-test

jmartin919 · Post by **jmartin919** » 05 Feb 2024, 06:12

That's what it is. Thanks

laser · Post by **laser** » 10 Mar 2024, 17:40

Thanks for answers.
It was control unit.

Post by **abscate** » 17 Mar 2024, 14:49

I’ll guess 990:10 control unit to pump failures on the P80 chassis

Post by **erikv11** » 18 Mar 2024, 19:41

I'll go 992:8