Output Speed Sensor Failure?

[Dubhead]

Folks,
I have been experiencing some issues lately with my 2001 V70 XC (165K) that are somewhat concerning. About a year ago, I had received a number of panicky messages that seemed to indicate that my ABS unit was failing ("ABS Brake Service Required" to "Brake Failure Service Urgent") as well as CEL and ABS lights coming on. I did have some intermittent cruise control issues (not holding set speed) at the same time and all things were pointing at ABS issue. I did not even have a chance to pull and send out for a rebuild from Vic Rocha at the time when all of the messages and issues disappeared, never to appear again. The car functioned normally including ABS all through the winter and onwards. Recently though things have gotten a little odd with the shifting, first noticing some flare between 2nd and 3rd (B4 servo cover?) and then a bit of just poor shifting. All fo the shifting issues being intermittent but more consistent as the car was driven for any significant period of time and presumably the system being at standard temperature.
I have Torque Pro for Android (great app) and a basic Bluetooth OBD-II module that allows for some basic code pulling. I used this when I noticed a "Transmission Service Required" message and found the following codes:
P1618: Cable fault between AW 50-Q2 TCM and Motronic 4.4 ECM (lamp lights)
P0721: Output Speed Sensor Circuit Range/Performance
P0722: Output shaft speed sensor circuit no signal

I was somewhat suspicious that these were still some indication of faults with ABS unit (even though not directly indicated by codes) based on some reading on forums about others experience with these codes. I pulled my ABS unit, shipped to Victor, he found nothing wrong but the memory in the ABS unit having a code indicating a permanent fault: ABS-0064 Stop lamp switch. His diagnosis was: Faulty signal, this is what is disabling your ABS system. So no harm no foul, nothing for him to repair or do but bench test and run in a test vehicle of his. No issues....interestingly it was not the original ABS unit that came with the car but neither here nor there.

Back to where I am at now. Had to call the dealership to see about an appointment to get the Output Speed Sensor(the one on the bell housing, not individual wheel sensors?) replaced and was given the quote of:

(1 hour diagnostic ($99) + 3.5 hours repair($350)) + part cost (303.39) + tax(9.5%) = $823.86 (approximate)

The price seems a bit steep and the part seems expensive so I wanted to get a sense of what other forum members have seen/paid for issues like this. Thanks for reading the backstory and all.

Cheers,
Dubhead :cool:

[Dubhead]

Just a quick update. Took the car in to the dealer and they confirmed that the problem IS the ABS module and want to do a full replacement for $1K!!! I am not sure what to do next as I declined to do the repair with them and want to understand why Vic Rocha found no issues with the unit? I will need to see about sourcing a new unit somewhere and do the install myself I guess unless there is\\ VADIS/VIDA update that needs to happen also. Now I am confused!

[andybbrown]

What happened? My car has same codes.

[TPWPXC01]

Dubhead- I have the same issues as you are with the occasional ABS light, CEL, and also, now appearing, an intermittent "Brake Failure- Service Urgent" warning when going around curves. (The latter just began yesterday.)

A few weeks ago I brought my '01 to the dealer service about the ABS warning and they concluded it was the ABS module. After making me order a new one at about $900, when they tried to install they found it was not the module but the ABS pump(?)-- which would cost $1500 for parts & labor. Being that ABS wasn't a necessity for braking, I declined paying the extra $600 balance over the ABS module and told them to nix the project. (I ended up getting shined to the tune of about $180 because they charged a 20% "restocking fee" on the ABS module which they claim they had to order from Sweden.)

Wondering if the new "Urgent Service" light is related, a further failure, or something like rotors or fluid level...?

Any advice appreciated.

[Astro14]

Xemodex rebuilds ABS modules. Or you could try these guys: https://www.midwest-abs.com/

But I wouldn't go with new...not at that price.

[andybbrown]

Thanks for the reply and the link: https://www.midwest-abs.com/Troubleshooting.php to the Midwest ABS module site.

I had resoldered a pair of two large pins, one of which had cracked, in the module. I did not do other pins that may have had microscopic fatigue. The car went well afterward, with no warning codes, for the past two years until recently.
Codes have come for the brake pedal sensor. I followed the directions of SwedishInside: http://www.volvoforums.org.uk/showthread.php?t=97192&page=5
but the result has come negative of fixing the entire problem.
Another code is a wheel sensor (left or right). This code has appeared frequently in the past and may not have gone from the previous repair. So I am going to change the wheel sensors.
I want to look for a physical cut or displaced wire as well in the link between the transmission TCM (?) and the ETM as these may relate to a motronic link code thing which is a code sometimes triggered. It is possible something has come loose in the module and that is priority.
I could possibly look into the pump with an ohm meter.
I am worried by "P1618 Speed sensor code. This is a TCU code. It isn't always caused by the ABS module. It can also be stubborn to clear with a common OBDII scanner. Same thing for the P1633 and P0500 codes" that was on the Midwest site.
Incidently, sort of a side note, I changed tyres to new recently. A few days after that, vibration and shakes started occuring and continue to do so between 15kph and 50kph. We rotated the tyres, checked balance, considered alignment. They may have looked at bent wheel. None of the above. I looked at the prop shaft and cv boots - both looking nice. I wanted to drop the prop and may do so but I find it needs 4 wheels off ground due to having to rotate the shaft to get it off. I had it nearly raised on two axle stands, a large floor jack and was building it up off of car ramps at front but just stopped and will go to a garage as the guy owes me a favour, to drop the prop. But, I do wonder if the vibration may be linked to these bloody codes.

My brother in-law looked at ABS wheel sensor from the point of view that my shakes is caused by the brakes applying and closing rapidly, as if in a continual anti-lock mode. He suggested driving around a quiet place (in NZ some quiet places) using only handbrake and check for heat built up by pads - however, that test turned up negative to diagnose shakes visavis the sensors. I tried raising the wheel sensors a little away from the cog to increase the hall effect and try and alter that but the shakes of car remain just the same. May not be wheel sensors causing the fault.
Lastly, there is the actual speed sensor on the transmission and the rpm sensor between the engine and trans.
Will advise

[andybbrown]

I towed a heavy trailer. Soon after the shudder and codes that were felt rhoughout the car, and the codes making the transmission light flash, stopped. For one full day stretching to three now with this update.
Codes did appear (wheels sensor once and speed sensor once) during small rain showers ...

It is as though something had to be squeezed, knocked or pushed back into its correct place through the weight of the 500kg trailer pulling at the engine as torque. In that case it could be the shaft of axles, a mount, perhaps something near the housings ..