Tracs abs speedo issues

[perhss70]

Just a question. Does a bad abs affect the cruise control? I checked that my cc pump worked. But it doesn't engage when I'm on the road. Even if the spedo is working. I will probably look at fixing the abs this week. Does anybody know if the abs must be working for the cc to engage?

[scot850]

Yes.

Neil.

[perhss70]

So today I did a lot of things. I made vol fcr work and pulled codes. 2 codes were persistent 314
And 443. I decided it was time to replace the module and so I did. After replacing the module I could clear the light but after some time it kicked in again. I got 314 and 324 regarding the rear right wheel sensor. I will replace it next. Also driving home I could feel my brake pedal kinda kicking when I pressed it lightly. I think that was the abs. Any suggestion or something i missed?
Cheers

[scot850]

When you replaced the ABS module, did you use a used on or a rebuilt unit. I consider most ABS modules from junkyards are bad.

We are fortunate in North America to have Matty who owns Mid-West ABS who repairs and warranties these units for P80 owners. I buy mine from him.

I had issues with one of my cars with random lights and issues with the speedometer. I pulled a junkyard one and it was only helpful in that it confirmed it was also bad but the faults changed. Off went both cores to Matty and a rebuilt one bought. All good after that.

I would do as you mention and check the ABS sensor on that wheel. There are resistance values you can measure to confirm if it is working and in specification.

Neil.

[perhss70]

When you replaced the ABS module, did you use a used on or a rebuilt unit. I consider most ABS modules from junkyards are bad.

We are fortunate in North America to have Matty who owns Mid-West ABS who repairs and warranties these units for P80 owners. I buy mine from him.

I had issues with one of my cars with random lights and issues with the speedometer. I pulled a junkyard one and it was only helpful in that it confirmed it was also bad but the faults changed. Off went both cores to Matty and a rebuilt one bought. All good after that.

I would do as you mention and check the ABS sensor on that wheel. There are resistance values you can measure to confirm if it is working and in specification.

Neil.

I'm from Greece and my dad sells used car parts for a living so I used a used one. I measured resistances of all sensors but the rear right sensor would not give me a clear value (value was jumping around) but was around 1.2KΩ. I have experience soldering so if the sensor doesn't fix the problem I might pull it out again and inspect it. Being in Greece means that I don't have specialists in volvos since the older models are kinda rare nowadays. Would I be able to solder a new sensor without replacing the whole wiring-harness? I saw that replacing both sensor and wiring is a pain in the ass

[scot850]

Having not done that, I don't know. The main issue is to maintain the resistance withing the required tolerance. If you can, then why not.

It may be worth checking the tone/reluctor ring is not dirty or rusted, or worse cracked on that wheel if you pull the sensor. Removing and cleaning is and the reluctor ring may be all that is needed.

Your dad may sell used parts, but unless you know the module was working before you removed it, it may not be good. Based on what you are saying though, I think you are on the right path.

Good luck!

Neil.

[perhss70]

Having not done that, I don't know. The main issue is to maintain the resistance withing the required tolerance. If you can, then why not.

It may be worth checking the tone/reluctor ring is not dirty or rusted, or worse cracked on that wheel if you pull the sensor. Removing and cleaning is and the reluctor ring may be all that is needed.

Your dad may sell used parts, but unless you know the module was working before you removed it, it may not be good. Based on what you are saying though, I think you are on the right path.

Good luck!

Neil.

You are right, when using used parts for cars that are 25+ years old it's always a hit or miss.
Maybe if I have many spares I can try soldering one. Matty can send me one for around 240$ but for me its like the final choice if nothing else works. I will check the reluctor ring and the sensor and hope for the best.

Thanks for the help.

[misha]

443 didn't came back?
https://www.volvotips.com/index.php/850 ... ce-manual/

1.2kOhm is proper resistance.
Not sure i understand the part when you said that you couldn't get steady reading.

I would also check the resistance at abs ecu main plug...here is a pinout:
https://midwest-abs.com/troubleshooting

Remove the rear sensor and give the sensing tip a good cleaning.
I bet that it's pretty rusty and...since it's magnetic...could be fouled up with metal debris.

If you will need to replace the rear sensor...don't cut the cable,splice it or crimp it...connectors are in the trunk near the fuel pump metal cover.

Like Neil said....could be that replacement module is also faulty since all of them fail beacuse of cold solders.

Open up your old one,resolder it and try it.
Otherwise...you will be chasing your tail on this.

When you re-install abs module and if problem is solved it will clear all the codes and warning lights itself as soon as you drive off and abs module perform it's self test....no need to clear the codes.

[perhss70]

443 didn't came back?
https://www.volvotips.com/index.php/850 ... ce-manual/

1.2kOhm is proper resistance.
Not sure i understand the part when you said that you couldn't get steady reading.

I would also check the resistance at abs ecu main plug...here is a pinout:
https://midwest-abs.com/troubleshooting

Remove the rear sensor and give the sensing tip a good cleaning.
I bet that it's pretty rusty and...since it's magnetic...could be fouled up with metal debris.

If you will need to replace the rear sensor...don't cut the cable,splice it or crimp it...connectors are in the trunk near the fuel pump metal cover.

Like Neil said....could be that replacement module is also faulty since all of them fail beacuse of cold solders.

Open up your old one,resolder it and try it.
Otherwise...you will be chasing your tail on this.

When you re-install abs module and if problem is solved it will clear all the codes and warning lights itself as soon as you drive off and abs module perform it's self test....no need to clear the codes.

443 was on the old module, new module only gave 314 and 324. About the ohm readings. I measured pins stated in Midwest troubleshooting page. 3 sensors gave steady measurements but rear right sensor was jumping around values. I will check again tho maybe It was my fault. I will also check for shorts. When you say main plug what pins do you mean? Tomorrow I will clean the sensor and check the ring for rust. Changing abs modules is a bit of a hustle due to an lpg conversion I have limited space. I want to rule out the possibility of the sensor and if all else fails I will solder the old unit and install it.

Thanks for the help

[misha]

Pinout is is the link i posted in previous post.

The main plug is a bit tricky to seat correctly...check if it is seated all the way down.
You can use a bit of wd40 on plastic connector rails to make it slide over easier.