Volvo 873992 Tachometer guage. Faulty

I

Ian MacAulay

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Morning.

My VP guage has stopped reading but it is preforming like a test cycle .. Every 20 seconds the needle goes to full RPM then back to zero again..

Any ideas?

Ian
 
Ian

You might want to consider the VDO equivalent at half the price. I replaced mine on a previous boat with VDO tachs.

Regards

Rob
 
Check the alternator connections first. The tacho takes it's readingsoff the alternator, then check wire continuity before assuming it's a tacho fault.
 
A few weeks go one of my tachometers played up for a day or so. It had been a wet day - instruments did get wet. Not the same fault as yours but it had been sticking at various positions on the dial.
After a good sunny day the tachometer function returned to normal.
So it had been affected by the damp conditions.
Try removing the tachometer and gently dry it out for a few days in a warm environment like an airing cupboard - worth a try.

.
 
They are the same size as the volvo gauges were made by VDO to their spec.
I cannot remember exactly but I think the dealer configured them for me. Apart from that they were a straight replacement.
The only difference was that the VDO ones maxed out at 5K RMP as opposed to 4K RMP. I could live with that given the price difference. Also the original volvo ones were not very sturdy I was told. The problems arise when over time the circuit board start to crack.

Rob

Rob
 
There is no replacement parts available for the original 873992 at all.... You need to buy a new EXPENSIVE one.
BruceK says that the gauge gets the signal from the alternator. In fact that could be correct but depends on the engine you have. The gauge an a KAD300 gets the signal from the EDC unit ... therefore if you want to buy an aftermarket part you better ask your dealer if you can return it if it does not work. Bad to sit on a part that is no good :-)
 
Looks lie the boat I was interested in with a damaged Tacho is a non starter. In case anyone comes across this thread in the future is the info I found....

If the 'glass' is clouded then there are products that should be able to make it clear again. The detailing forums seem to be a good place for more info.

If the glass is cracked then it might be worth investigating if other VP instruments of the same size have the same glass. check eBay. Alternatively there maybe companies that will make a replacement but I haven't found one yet.

If you've got a broken hour counter then this link is worth a read:

https://verl900.wordpress.com/technical-articles/vp-md2020-tachometer-repair/

Note that comments that state that sometimes you can get the hour meter to function again by heating the ribbon with a hair dryer. Looks like these guys will replace the hour counter for you:

http://www.monkey-tuning.com/produc...language=en&XTCsid=teop5mvf4pv8pf18tdstsgcfi5

Otherwise you may have to buy new units at around £300 a piece.

Pete
 
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