940 fuel and coolant gauge issues-already repaired before?
 

The hpt we are picking up tomorow has a faulty gauge. Fault is all the way to top and occasional drop to 0 with light. The car had a new board fitted by volvo in the past so is there any areas to check instead of clock?


Really not keen on the idea of a failed fuel gauge

Thanks
Mick

If the low fuel light is coming on when it drops to zero that suggests the fault is more likely to be with the wiring or in-tank sender than the actual gauge or PCB. The latter faults tend to result in the gauge dropping to zero without the low fuel light.

It would be worth finding the four-wire multi-plug in the rear cubbyhole and experimenting with jumpering the thinner two wires. I expect someone will tell you the rating of resistor you need to use to do this safely and get a particular reading on the gauge. I just go for shorted = full and open circuit = empty.

A similar approach will enable you to test the temperature gauge. The sender is the easier (front) of the two to reach under the inlet manifold. Again, open circuit = stone cold and shorted = off the scale. Use an appropriate resistor to get a mid-scale reading and avoid the risk of damage to the gauge.

I will have a look thanks, any tips for sender unit? what to expect etc or failure points?

Wish someone coud sort this problem out there's seems to be a few different fixes even banging the dashboard is suggested my fuel gauge got fixed by soildering but temperature gauge not worked for years even after trying a third dash panel ..is it the connector block on wiring harness if so there's 3 blocks with a lot of pins so which one is is it that gives it the supply I've changed the gauge too .I now have my resivor connected to the low washerfluid so at least that comes on when the coolant resivor is low but I would like coolant gauge to work

Does the obd2 port offer much functionality on 940s? There is always the option of a odb2 temperature gauge if the data is there? Good short term fix

It's not actually OB2

No, see Marks reply ^^^^^

Don't even bother hooking up a generic OBD-II reader as it won't work. :nah:

https://www.volvoforums.org.uk/showt...fuel+guage+fix

Have a read of that for the likely causes of guage faults and possible fixes.

Tank sender removal without dropping tank...discuss.. :regular_smile:

Is it doable? I have seen one person say they did it in the states?

Mick

That's the standard method when changing the in-tank pump Mick. :err:

Many of us have done it on here - you'll need a new sealing ring from Volvo though, about £11.

In fact, it's almost impossible to remove the tank without first removing the sender.

***EDIT*** I'd investigate the instrument end of things first though, the senders are fairly reliable by comparison. The easiest fix and first thing to try is remove the instrument cluster, clean all the contact points for the multiplugs then clean the contacts in the plugs. While cleaning the plugs, use a thin screwdriver "behind" each contact to enhance the "bow" shape of them so they make better contact with the contacts on the PCB/instrument cluster.

Check my link above for deeper repairs on the cluster PCB as well.

That's lovely to hear. The previous reading i had done suggested it was a tank off affair due to angle :rolleyes:

The reason i suspect the sender so much is because the gauge reads full not 0. I still have the d24 here with a working fuel gauge and its a later car too i think so the clocks should be swappable to test fuel at least?