ABS diagnostic conundrum 1997 V70R - Page 2

Yog Sothoth · May 11th, 2022, 16:16

Quick update on this (sorry it's a bit late in the day):-

I ended up taking the car to a place in Sheffield which can do OBD on older Volvos. He diagnosed a failed rear ABS sensor. I had both rear sensors replaced, which wasn't cheap, and bingo! The lights were still on! Aaargh!
The Auto electrical guy ran OBD again and there was nothing wrong so the fault had to be in the ABS ECU - he reckoned the faulty sensor had maybe caused some issues in there.
I told him about Volvo Diagnostics and their warranty and he offered to ring them on my behalf, which he did. He was able to counter every suggestion they came up with until they said OK, send it back.
I sent it back, and they honoured their repair warranty, and touch wood, it's now OK.
So Volvo Diagnostics are reasonably priced and will honour their warranties, as long as you can convince them it can't be due to something else. A friendly and persuasive auto electrician helps though!

aarongs · May 12th, 2022, 21:42

Thanks for updating this!
I am about to try to get this issue fixed so the is really helpful. Thankfully my garage can scan the car as a start. Hoping it a relatively simple fix too.

RollOn · Jul 29th, 2022, 04:43

Quote:

Originally Posted by Yog Sothoth

Would you say it’s worth buying a scanner? I see there are some fairly cheap ones but I know nothing about these things.

This one: ( https://www.ebay.com.au/itm/393946231717 ) successfully scanned ABS fault codes (Wheel sensors, ABS Pump) on my 1998 Volvo S70. (Other scanners on eBay fail to recognise early Volvos)

RollOn · Jul 29th, 2022, 04:46

ABS Module/Control Unit: 4 years ago I re-soldered the 2 big/main posts (to power connector). This immediately fixed the ABS fault. This week, I again received multiple fault codes for open circuit wheel sensors and ABS pump fault. So, I wasted much time swapping wheel sensors without luck. Initially, I was convinced that the ABS Module/Control Unit (ECU) was no longer the problem. As a last resort, I properly de-soldered and then re-soldered all the smaller solder joints (inside the ABS control module). This again immediately removed all ABS fault codes.
Note: Dry joints (solder) only occur where the pins (for external wiring harness) are connected to the circuit board. (no other part of the board has problems) Every Volvo of this model has/will eventually have this ABS problem. Caused by faulty manufacture, “Made in Philippines”. Do not waste time on anything else until you have properly repaired the ABS ECU. (If properly de-soldered and re-soldered it should never again cause problems).
See Tutorial: https://www.matthewsvolvosite.com/fo...f6426ea4060a29

sdg1970 · Jul 30th, 2022, 17:25

Shemtek did mine and the light was still there. It turned out to be an O/S/R wheel sensor, which D&A Autos diagnosed and replaced.

May 11th, 2022, 16:16	#11
Yog Sothoth New Member Last Online: Mar 7th, 2023 09:32 Join Date: Jan 2020 Location: Sheffield	Quick update on this (sorry it's a bit late in the day):- I ended up taking the car to a place in Sheffield which can do OBD on older Volvos. He diagnosed a failed rear ABS sensor. I had both rear sensors replaced, which wasn't cheap, and bingo! The lights were still on! Aaargh! The Auto electrical guy ran OBD again and there was nothing wrong so the fault had to be in the ABS ECU - he reckoned the faulty sensor had maybe caused some issues in there. I told him about Volvo Diagnostics and their warranty and he offered to ring them on my behalf, which he did. He was able to counter every suggestion they came up with until they said OK, send it back. I sent it back, and they honoured their repair warranty, and touch wood, it's now OK. So Volvo Diagnostics are reasonably priced and will honour their warranties, as long as you can convince them it can't be due to something else. A friendly and persuasive auto electrician helps though! __________________ Saffron Volvo V70R 1998 2.4 Auto

May 12th, 2022, 21:42	#12
aarongs Junior Member Last Online: Apr 19th, 2024 20:10 Join Date: Oct 2014 Location: Edinburgh	Thanks for updating this! I am about to try to get this issue fixed so the is really helpful. Thankfully my garage can scan the car as a start. Hoping it a relatively simple fix too.

Jul 29th, 2022, 04:46	#14
RollOn New Member Last Online: Aug 23rd, 2022 06:22 Join Date: Jul 2022 Location: GUNNEDAH, NSW, Australia	ABS Module/Control Unit: 4 years ago I re-soldered the 2 big/main posts (to power connector). This immediately fixed the ABS fault. This week, I again received multiple fault codes for open circuit wheel sensors and ABS pump fault. So, I wasted much time swapping wheel sensors without luck. Initially, I was convinced that the ABS Module/Control Unit (ECU) was no longer the problem. As a last resort, I properly de-soldered and then re-soldered all the smaller solder joints (inside the ABS control module). This again immediately removed all ABS fault codes. Note: Dry joints (solder) only occur where the pins (for external wiring harness) are connected to the circuit board. (no other part of the board has problems) Every Volvo of this model has/will eventually have this ABS problem. Caused by faulty manufacture, “Made in Philippines”. Do not waste time on anything else until you have properly repaired the ABS ECU. (If properly de-soldered and re-soldered it should never again cause problems). See Tutorial: https://www.matthewsvolvosite.com/fo...f6426ea4060a29

Jul 30th, 2022, 17:25	#15
sdg1970 Master Member Last Online: Jan 19th, 2024 17:18 Join Date: Jun 2012 Location: Hell	Shemtek did mine and the light was still there. It turned out to be an O/S/R wheel sensor, which D&A Autos diagnosed and replaced.

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