99 V70 Odometer Issue

talbotpj · Post by **talbotpj** » 21 Jul 2018, 19:01

Recently acquired 99 V70 NA Automatic, 97k miles. I bought the car last week and upgraded the ETM with a contact less sensor today. I drove it for the first time tonight. ETM issues are solved, no more CEL. ABS and Brake lights come on so i'm thinking the ABS unit will need to go to Midwest.

While driving tonight I noticed the odometer adding mileage rapidly. I drove approximately 5 miles, the odo put on 70 miles.I don't have much history on the car so can't say if this was happening prior to the ETM fix. PO did not bring it up.

Any thoughts?

TIA

Pat

Post by **RickHaleParker** » 22 Jul 2018, 00:02

The Speedometer and Odometer are part of the ABS system. They both use the data from the ABS wheel sensors.

I would start with a remanufactured ABS module. Cracked solder joints on the ABS connector is a common defect with the Volvo P80 series.

I'll place my bet a remanufactured ABS module will clear up the ABS and the Odometer problem.

Post by **abscate** » 22 Jul 2018, 06:02

That is a funky one !!

Ping mattymoo at MIDWEST ABS and ask if he has seen that failure

Post by **Ozark Lee** » 22 Jul 2018, 10:31

That is odd, the normal failure mode is to have no speedometer and no odometer when the ABS fails. There is a miles vs kilometers programming toggle in the cluster but that wouldn't account for a 70 mile tally in a 5 mile trip even if it was wrong.

...Lee

Post by **RickHaleParker** » 22 Jul 2018, 19:44

Hum .. from what I can gather the odometer records are stored in the CDM/DIM.

Could it be that his CDM/DIM has lost it's sanity and the ABS module is fine.

I do know there is a signal in the CDM that is 12 cycles per revolution of the wheel and can be used for accessories. There is also a CPU in the CDM. it seems to be a rational assumption the the CDM CPU uses the 12 cycles per revolution to calculate the distance. If the 12 cycles per revolution where off, the speedometer should be off also. If the speedometer is correct, that would indicates the data from the ABS is good and the defect lies in the distance calculations.

The CDM CPU also turns the indicator lights on and off, if it had mental problems it could very well turn on the ABS and Brake lights when there is no problem with the ABS or Brakes.

I might just lose the bet, good thing I did not wager.

talbotpj · Post by **talbotpj** » 23 Jul 2018, 10:38

Interesting. I am going to pull the ABS unit and send to Midwest first to see if that resolves the problem. No harm in spending the $80 even if the unit is OK (it likely won't be for much longer).

If this does not fix it i'll look into CDM/DIM. The speedo is generally correct but it jumps while accelerating. Not nearly as concerning as the odometer issue - not many 20 year old Volvos with less than 100k so I'd like to keep it that way!

I'll report back - thanks for the help!

EDIT - it does not appear the CEM was implemented yet in 1999.

Pat

Post by **abscate** » 23 Jul 2018, 19:30

Driver display module on the 99 maybe?

Post by **RickHaleParker** » 23 Jul 2018, 21:02

On the '99 they may have stored the mileage in the CDM and ECM. My understanding is that the the mileage is stored in two places, when the system boots it uses the higher of the two and syncs the two. This is to prevent odometer rollback by swapping out a unit with one with a lower stored mileage.