Quote:
Originally Posted by v8volvo
Been a while since I have had one of those clusters apart but to my recollection there is a little voltage supply unit somewhere on the back of the cluster that feeds power to those two gauges, since IIRC they run at less than 12V. Maybe if that unit were failing or if it had a crack in a cold solder joint, it could cause the gauges to temporarily quit working?
When the fuel and temp gauges drop to 0, does the speedometer and tach and warning lights still work fine? In other words, it's just the fuel and temp gauges that seem to be having a problem?
If you slap the dash or somehow shock the cluster, does it ever get the gauges working again, like there's a loose connection that is getting jostled?
I'm pretty sure the whole cluster gets power from one source and then distributes it to the different gauges so don't think it could be a fuse or circuit problem but can double check on that. Think I have the greenbook diagram somewhere for the cluster.
One thing you might try would be swapping in a known good different cluster temporarily, to see if the issue disappears with a different cluster. I think I have a spare one for an '84, worst case scenario I'd be happy to send it to you and you could give it a try.
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Hi,
I have a very similar issue.
In my case it is the Voltage gauge and the Temp gauge.
It used to be the Temp gauge
only, acting up since many yrs ago.
A knock (1 gentle tap) on the lower lip of the instr cluster (right in front of the temp gauge `platform`) usually (=always) fixed it then it worked for the trip. This changed.
Recently it happens
more often and the Voltage Gauge
joined the Temp gauge in doing it. The knock usually fixes both...but often it needs more than one knock, or one that`s stronger than a gentle tap.
A single knock still helps but not always....at the same location or near the Volt gauge, or at both gauges... then it works for a while.
But then, it sometimes happens again on the same day/trip.
These two gauges BTW are out pretty much every time I drive the car now. The cluster needs the knock... almost every day.
I used to have the large panel/cover removed from below the steering wheel (above the driver`s knees) and I kept it like that for many years... I was lazy to put it back for a long time but recently reinstalled it a few months ago. As you said, this is probably the reason why it does it more often (maybe there is more
heat around the instrument cluster).
It is super annoying, I will take the cluster out and inspect the solder joints.
My speedometer and tach, lights, etc everything else in the cluster works well despite those two gauges (Voltage and Temperature) being out. ((They aren`t out all the time))
Extra info:
The fuel gauge works abnormally, shows low when full and shows full when empty. And not sensitive to the level. It is either at left or middle or at the right side. That gauge is not related to the other gauges, I think. Maybe wrong wiring or mismatched connectors at the fuel tank, I have no idea, I just learned to live with it.
But having the Temp gauge is the minimum d24 health insurance.
(Exra info: In my 1986 740 car, the voltage gauge is the
left upper corner. The fuel gauge is below the Voltage gauge.
The temp gauge is on the
right , it is the lower corner of the instr cluster (below the turbo gauge =top right)
Could you please circle the voltage stabilizer on the third illustration? Thank you.
I will take a picture of the back of the cluster or a spare td cluster I have. So far, I replaced one of the four Yazaki larger bulbs because it was out (from the knocks the temp gauge needed)
I will compare the fuel gauges of my spare cluster with the one in the car, and probably try swapping them to see if the spare fuel gauge will work in my cluster or not. If you think the problem lays somewhere else, pls let me know so I can save some time.