The odometer gear is a weak point in the Volvo 850, among others. Unfortunately this brute of a vehicle may last forever, but most owners won't know the true mileage due to the brittle plastic that drives the odometer.
Depending on the year, it is possible to read the true mileage out of any Volvo 850, even the 96-97 that were equipped with OBD-II only.
93-95 (OBD-I)
Under the hood of these vehicles lies an OBD-I DTC socket. This is equipped with an LED, button, and "fly-wire."
To read the mileage stored in the cluster, insert the fly wire into socket A7.
Press the button five times.
When the LED illuminates solid, enter the code 1-1-1:
- Press the button once, wait for the LED to go out, LED will re-illuminate.
- Press the button once, wait for the LED to go out, LED will re-illuminate.
- Press the button once, wait for the LED to go out, LED will re-illuminate.
The light will now respond with the last three digits of the odometer mileage, in "blink" form. I'll use 105,738mi as an example.
(105,738mi would blink seven times, pause, three times, pause, 8 times)
To attain the first three digits of the true mileage, press the button again five times.
When the LED illuminates solid, enter the code 1-1-2 in the same format as you did earlier and wait for the response code.
105,738mi will blink one time, ten times, five times. Ten blinks indicates a zero, so if the vehicle has less than 100,000 miles, it will blink ten times first. (095,738mi)
96-97 (OBD-II)
While it may not be possible at home, it is possible to read the mileage out of a 96-97 vehicle. Any Volvo dealership or some Volvo independent shops will have a Volvo VST in their arsenal. This tool can read the mileage directly out of the cluster.
Select ELECTRICAL, COMBI, PROGRAM COMBI. Select READ COMBI, and the cluster's mileage should be shown on the following menu.
I slid around the back of my dealership's service department and gave a tech $20 to do this under the table. The service adviser turned me away, stating that my mileage was in the odometer, and if I wanted to read it, I should look at the dashboard. In most cases, it's best to catch a tech on their lunch break, since many advisers do not know of this and may try to charge for a full hour of labor when this job takes under five minutes.
Repair
After I got the correct mileage of my girlfriend's 97 850 read at the dealership, I immediately went home and tore the dash apart to repair the broken odometer gear. Since it was 9 miles from the dealership to my house, I added 9 miles to the number they gave me. While I won't go in to detail, it is possible to disassemble the odometer during the repair and modify the mileage to the correct figure if you're clever. Since we had no idea when the odometer stopped working, it was great to get the actual mileage back on the dash.
