Dash Lights Not Working - '98 940

[Cylinder 8]

Hi All,

I noticed the other evening that all the backlighting in my 940 has stopped working, both in the instrument cluster and the heater controls. All other lights still work (warning lights, indicator arrows etc.) just not the back lights. I've done some research which has pointed me to the dimmer switch, but I've tested it and it seems fine. Power is reaching the instrument cluster through the green and brown wire from the dimmer switch, and the voltage goes up and down as the switch is adjusted.

Is there any way to test the rheostat that's mounted on the back of the instrument cluster? I also can't find out where the lights are earthed, so if anyone knows that would be useful too.

Thanks

[Aubergine S70]

Hi, I’ve got this problem on my 1990 760 turbo diesel.
The car had been stood for 3 years and with a weeks work it’s now roadworthy. The other day at the traffic lights, smoke was coming from under the passenger seat when the heated seat was on by accident. After this 2 miles down the road the instrument lighting had just failed and more smoke. Turns out the fuse for the backlighting had melted randomly don’t know how.

It would be interesting to see the common issues

Thanks

[bob12]

Assuming that both a 760, and a 940, have a Yazaki oem instrument cluster?

[Laird Scooby]

Originally Posted by bob12

Assuming that both a 760, and a 940, have a Yazaki oem instrument cluster?

They do Bob. I was doing some digging the other day, trying to source a replacement fuel gauge for my beastie.

The facelift 760 from 88-92, facelift 740 from 90-92, 940 and 960 up to 93/94 time all had Yazaki but the fuel gauge is NLA sadly. Later 9xxs used the same instruments but under different part numbers as the background was grey, rather than black.

I suppose for my part i could use a later gauge and change the background but instrument clusters are selling for a ridiculous amount these days. When i bought the cluster for my 740 (for the same reason, dead fuel gauge + dead tripmeter and odometer) it cost me a relatively sane £30 but most of what is listed on fleabay are around the £80 point for complete clusters.

It's easy enough to change just the fuel gauge but nobody seems to be selling individual instruments and i don't see paying that much for what is effectively just one instrument. The rest of mine work and the odo is just about (in the next 10 miles) to turn over 225k so i'm kind of reluctant to change the rest of the instruments anyway.

[bob12]

I haven't yet seen a '90 or '91 G /H reg 745 facelift with a Yazaki Dave, at least both of mine have still have the VDO. Yes, the prices of clusters has gone totally stupid and you can't even guarantee any of the gauges are working if you bought one! Glad I have a few spares 'in stock' that keep my VDO going. It seems as though it's only the fuel gauge and speedo that play up. Bob.

[Laird Scooby]

Originally Posted by bob12

I haven't yet seen a '90 or '91 G /H reg 745 facelift with a Yazaki Dave, at least both of mine have still have the VDO. Yes, the prices of clusters has gone totally stupid and you can't even guarantee any of the gauges are working if you bought one! Glad I have a few spares 'in stock' that keep my VDO going. It seems as though it's only the fuel gauge and speedo that play up. Bob.

Maybe i'm mixing my gauges then, have a look at these and see which is which :

Pre-facelift 740 (1988) :



Facelift 760GLE (1988) :



That was June last year, seem to be averaging 3k a year in the wee beastie!

PS - if you happen to have a spare, working fuel gauge for the bottom cluster, i'd be interested!

[bob12]

The top two are VDO's (one of which has 'your' fuel gauge inserted), and the bottom one is a Yazaki. Doesn't it look odd with the trip at the top!

I may have a fuel gauge from a very old Yazaki somewhere (I took out the volt meter and put it in my VDO and then because the dials didn't look 'balanced' I also put the turbo gauge in although I have no turbo!). I'll have a look and send you some photos. Bob

[Laird Scooby]

Originally Posted by bob12

The top two are VDO's (one of which has 'your' fuel gauge inserted), and the bottom one is a Yazaki. Doesn't it look odd with the trip at the top!

I may have a fuel gauge from a very old Yazaki somewhere (I took out the volt meter and put it in my VDO and then because the dials didn't look 'balanced' I also put the turbo gauge in although I have no turbo!). I'll have a look and send you some photos. Bob

All the references to fuel gauges and instrument clusters i found from the points mentioned were for Yazaki Bob, including on the Volvo Parts Webstore - i know that is USA based but usually if you pick through, you can find the relevant information.

That's why i posted the pics, the bottom one seems to have been carried over into the 940 (all years) although on later 9xx they are grey rather than black background.

Would definitely be interested in the Yazaki fuel gauge Bob, thanks!

[bob12]

Originally Posted by Laird Scooby

All the references to fuel gauges and instrument clusters i found from the points mentioned were for Yazaki Bob, including on the Volvo Parts Webstore - i know that is USA based but usually if you pick through, you can find the relevant information.

..........

Yes, I am aware that Yazaki's were quite often the favoured cluster in later N.American 700 Series. Why, I know not!

At some point/s in manufacturing time European/UK 740 Series had Yazaki's, but not latterly, except 760's.

Should anyone want to try and buy (not recommended .... repair it yourself) a 2nd hand VDO cluster/speedo for just the speedo you have to watch out because the VDO speedo changed in design in it's connection to the white backboard in about 1986 or so, and will not fit a later say 1988'ish + VDO.

However, you can swap the warning light plastic strips and you will find that one VDO serves many system variations as it all depends on the loom input variations. I could assume that's the same for a Yazaki.

Bob

[Laird Scooby]

Originally Posted by bob12

Yes, I am aware that Yazaki's were quite often the favoured cluster in later N.American 700 Series. Why, I know not!

At some point/s in manufacturing time European/UK 740 Series had Yazaki's, but not latterly, except 760's.

Should anyone want to try and buy (not recommended .... repair it yourself) a 2nd hand VDO cluster/speedo for just the speedo you have to watch out because the VDO speedo changed in design in it's connection to the white backboard in about 1986 or so, and will not fit a later say 1988'ish + VDO.

However, you can swap the warning light plastic strips and you will find that one VDO serves many system variations as it all depends on the loom input variations. I could assume that's the same for a Yazaki.

Bob

Maybe i should have been clearer Bob, many of the secondhand clusters i found on ebay were Yazaki, others were "anonymous" but it was ebay UK i was looking on. I only mentioned the USA site as that kind of adds to the theory Volvo went Yazaki on us from about 1990 onwards.

As a general thing, Volvo over-engineered most of what is fitted to their cars but things like the fuel gauge, odometer/tripmeter, lighting rheostat and so on leave a lot to be desired. Several other things i've found that could do with improvement but they're all relatively minor as in none of this lot will stop the car from running, just cause minor inconvenience. That "minor inconvenience" grows in percieved annoyance because it shouldn't happen in an otherwise wellengineered car.