924Board.org

[pmcaya2]

I was working on another car ('60 T-Bird), so my '82 924 decided it needed attention - I swear that they're a jealous car.... and they sometimes fix themselves.

Anyway, I just put it on the road after winter storage. When I drove it tonight, the spedo doesn't work but the odo trips off the miles. No noise or other problems. Can I presume that the cable's OK and the spedo has an internal problem? Could it decide to work again? - Just a bad attitude?

[Fasteddie313]

Naughty Girl!!!
_________________
80 Turbo - Slightly Modified

[jason c]

[pmcaya2]

I wasn't kidding about fixing itself - the spedo now works like nothing was ever wrong.

Diagnosis: jealousy and competing for attention. This isn't the first time "she" has acted this way, but I'll try to do better - maybe an oil change?

PS VDO are fine instruments and almost never fail, so I'm not surprised that it started working.

[larchie]

If this is the only faulty instrument, and either your parking brake light doesn't flicker when on or the tachometer is erratic, the fault is probably the gauge as jason c notes. The brown ground wire from the speedometer connects to terminal 2 of the instrument cluster before grounding near the fuse/relay board. Rarely, however, erratic operation without additional other instrument problems is due to faulty grounds alone. But if this is suspected, especially check and clean the ground near the fuse/relay board, near the distributor, and the brown-wire ground terminal at the case itself.

If not that, VDO speedometers still have parts available and a "how-to" guide for disassembly of VDOs to correct for erratic readings is detailed on this PDF: Volvo 700/900 Speedometer Repair. (Many of the specific electronic fixes given there for erratic functioning are directed to the electrolytic capacitors on the Yazaki rather than the VDO speedometer so you'll have to ignore much of the full document.)

Nevertheless, now that the speedometer "healed itself," the problem might not be with the internal circuit. It's worth checking the integrity of the brown-ground wires terminal connection (going to terminal 2 of the instrument cluster and terminal 4 of the tachometer) and the green/blue-wire terminal connections from the 58b terminal of the instrument-cluster illumination-potentiometer and from the + terminal of the tachometer.

[pmcaya2]

Thanks for your post larchie! I realize that my last post was somewhat frivolous and I appreciate your expert advice. People like you make this forum the best I've ever used.

It makes perfect sense to check the grounds and I need to do it - a 32 year car just might have some corrosion. I'll follow your advice and post again.

All other instruments work but I definitely have a short in the panel lights circuit. I've been running without panel light fuse fuse because I'm afraid to fry the light switch, but I believe that this is a separate issue.

[larchie]

jason c has kindly pointed out (by PM) my apparent confusion in the post above of the electrical panel lighting circuit with the mechanical functioning of the speedometer/odometer. The troubleshooting suggestions about possible electrical faults were not meant to explain the erratic mechanical operation -- but as I re-read my post it looks like that is what I said. Since the fuse is missing, the electrical checks I suggested aren't really relevant in fixing the speedometer lighting and rest of the panel lighting circuit. Thanks jason c for clarifying my muddled post.