chasing dead interior/dash console lights

[SonicAdventure]

1996 Volvo 850 base: I replaced my shift lock solenoid this past weekend. While I was in there, I replaced the burnt-out shifter light bulb with a spare from my V70.

I also removed the burnt bulb from the front ashtray light receptacle. I also pulled the burnt bulb from the rear of the console that lights the console interior and the rear ashtray. When I hooked everything back up, no shifter light, and the trim ring light on my cigarette lighter is also out (it was working before). All the other switches on the console are working, lights, windows, seat heater, etc.

Within the next day, the bulb that illuminates the time and temperature was out. The clock still works it just doesn't light up anymore. The rest of the instrument panel illuminates.

Is there some kind of shared fuse or circuit for the console lights, and does it connect to clock illumination? Would removing the two dead console astray bulbs (front and rear) cause an interruption of a circuit? I chucked the dead bubs so I can't test that theory. Chasing these bulbs is a pain.

[abscate]

If you can fund and post the wiring diagram I think everything is in parallel there.

It’s the a Goddess of Coincindece at work, I fear

[SonicAdventure]

If you can fund and post the wiring diagram I think everything is in parallel there.

It’s the a Goddess of Coincindece at work, I fear

Ugh, not looking forward to pulling the dash pad but I really miss not seeing time and temp at night. While I'm in there I might as well fix the trip odometer gear as that is something that has been bothering me as well.

Is it possible to add the trip computer to a 96 N/A, not a whole gauge cluster swap but just the Info module? If I can come out of this with three upgrades/repairs it will be worth it.

[erikv11]

I also think it is most likely just burnt out bulbs.

To add trip computer on a 96 the cluster is indeed already able to use it. You just need to to grab the computer/clock module to replace your clock-only, and the info switch from another 850 that has them, plug them in and it works. There may be a separate little harness piece to grab also like from the computer to the info switch, I do not recall but should be obvious when you get in there to pull it.

[Clemens]

Pulling the dash pad and instrument cluster isn't that bad. did it twice last year.

[SonicAdventure]

I also think it is most likely just burnt out bulbs.

To add trip computer on a 96 the cluster is indeed already able to use it. You just need to to grab the computer/clock module to replace your clock-only, and the info switch from another 850 that has them, plug them in and it works. There may be a separate little harness piece to grab also like from the computer to the info switch, I do not recall but should be obvious when you get in there to pull it.

Interesting... assuming the trip computer is pulling data from the ECU, it would have to be from a 96 or 97 only then to work in my car, right? I've seen some pre-OBDII 850 trip computer components on ebay (92-95) but nothing listed for a 96-97. And I'm assuming a 70 series trip computer unit wouldn't physically fit in an 850 cluster - or would it?

[erikv11]

70 series the trip computer (TC) is already built into the cluster, there is no module there. Either the cluster has it activated or not. You can just swap in an activated cluster in the case of the 70 series, I've done that a couple times.

Just based on what people have done successfully over the years I am pretty sure a 95 trip computer works in a 96-97, I don't think the trip computer communicates with the OBDII. 94 I am less sure of, in general I always stay away from any parts 94 or earlier. There were quirks. Anyway I am pretty sure the TC info comes straight from the cluster. For example true cumulative mileage is stored in the cluster not the ECU, though you do have to go through the ECU and PBD to retrieve mileage.

One important thing is make sure you do not get a TC from a Yazaki cluster, which were more common in the older years, those would use a different TC (if in fact they ever had a Yazaki TC?). Unless of course your cluster is a Yazaki but those are uncommon. You presumably have a VDO cluster; there were two types. Next you're going to ask me how to VDO from Yazaki and I'm going to say ... I don't remember, the search function is your friend! Tons of threads about it in the archives here and elsewhere.

MVS member misha may have good recall about Yazaki vs. VDO cluster.

[SonicAdventure]

Thanks Erik,

Based on my research, the primary telltale signs with these clusters is the Yazaki unit features rpms that go to 8k whereas the VDO stops at 7k.

Also, the Yazaki odometer is above the speedometer needle and the trip odometer is below. On the VDO unit, both the analog odometers are below the speedometer needle but the trip odo is above the regular odo.

I got a spare VDO cluster at the junkyard the other day to pick lightbulbs from. I also need to fix the trip odometer reset on mine and I hope I can get the spare parts from this extra one without swapping the whole mileage counter unit.

In my current car, both odometers work, but the trip odo won’t reset with the pin. Not sure if that’s the rest arm spring linkage or if there is a separate gear that the arm pushes to reset it. I guess I will find out once I dig in. I don’t think I’m the first one to have issues with trip reset failure in an otherwise working unit.

[erikv11]

Sounds like you're on it.

Once you get the trip odometer rest working, one way to keep that all working is to never push the reset when the car is in motion. Or just never push the mechanical trip odo reset again - which is easy to adopt once you get a trip computer installed!