Yes! Instrument clusters have been completely electronic and are usually exchanged for years. They require specialists to repair/rebuild. There is no speedometer cable anymore, there's a transmission speed sensor, etc.

As you said, you can keep track of the mileage with the trip computer. If you want to fix this or not may depend on a number of variables, including how many miles you have on the car, if you plan to ultimately sell/trade it or drive it until the wheels fall off, and exactly how annoying you find the lack of an odometer. If you're really lucky, maybe the *&^%$# service reminder light was cooked along with the odometer!

VDO and Yazaki both made the Volvo 850 instrument clusters. To differentiate, on the VDO both the odometer and the trip meter are located above the speedometer needle. On the Yazaki, the odometer is above the speedometer needle and the trip meter below it. Also, on the Yazaki the service interval couinter is manually reset on the panel itself. The VDO incorporates an ECU microprocessor that incorporates a diagnostic function. In the event of a fault, a fault code will be stored in the ECU memory for subsequent read-out via the on-board diagnostic unit in the engine compartment. Many European makes, including Porsche, also use VDO instruments. There are a number of certified service facilities, and if you extract the instrument cluster yourself, and deal directly with them, you may be able to save a few bucks.

An independant Volvo specialist shop may be able to do it for less, too.

From what I can see from the Haynes manual, getting the 850 instrument cluster out is not such a horrible job, as opposed to most cars! (Ask the mechanic if he's ever had to do this job before!)

In fact, this is the entire set of instructions: "1.) Remove the fascia top cover as described in Chapter 11 2.) Disconnect the wiring connectors at the rear of the instrument panel 3.) Release the two clip locks at the front and lift out the instrument panel" (Step one does NOT require removing the steering wheel, at least according to the Haynes manual. The passenger's airbag does come out along with the top cover, so one has to be careful...)

I bring this up only because it doesn't sound like that part of the job should cost a fortune.

Since there are microprocessors involved in all of this, as a long shot I might try disconnecting the battery overnight, but it's just a long shot!

Good luck!

-Uncle Olaf