940 instrument dash rear printed circut?
 

hi has any one had problems with there instrument dash lights. as i cant get 2 out of the 4 to work i have swopped them round so it is not the bulbs or bulb holders its the right hand side where the temp gauge and rev counter is . not good on dark nights now . your help needed

Presumably you've removed the instrument panel to do this?

There are 4 main bulbs, in holders, for the panel illumination, and about another 12 underneath for the various warning light circuits..Also 3 above which are often overlooked.

(See next post as I can't add a picture now.)

Did you check that the bulbs are sound, and working in the holders BEFORE replacing them in the rear of the panel. Could be a dodgy holder... If they ARE working, have you twisted them round to lock them into place? Personally I'd use ALL NEW bulbs, because whilst you've got it all out, it makes sense to do it as the the capless bulbs are only about 50pence or so each.

Have you reconnected the ribbon cables firmly, and the earth cable?

If you have done all this, then you have a fault with the actual PCB, and it's a question of looking at it very carefully preferably with a magnifying glass or somilar, because you must have a break in the solder somewhere on the circuit that feeds the bulb holder in question.

I'd get all 4 out again, put NEW bulbs in, and then test them in the holders BEFORE replacing them. Sometimes old bulbs look OK, but aren't. To have two working and two not suggests the bulbs to me.

As above:

RED are the 4 Main Bulbs, and Green are the top three.

thank you oilydad for your valued info
i have replaced the 4 bulbs with new . i have taken the ones that dont work and put them in the working sockets and they then work the item you said about ribbon conection i have not done . i looked at the 3 small lamps at the top of the dash . the 2 outer ones on my car are the indicator . the centre 1 i replaced the lamp but still not on . so the 2 on the right . for temprture and rev counter are dead along with the small one in the centre top 1 the indictors are o k i swopped them for the top centre 1 but still no luck .
i just hope you may have more thoughts on this thanks

Unfortunately then, it looks as though you've got some problems with the PCB.

In the circumstances, I'd be on the lookout for a replacement instrument panel, unless you plan to spend hours checking every single solder run on your existing board. It's either that, or just live with it.

You've got to remember these cars are old now, and the PCB's get extremely brittle, and the instrument panel itself will probably have done its mileage as it were.

Maybe a member has one for sale. try a Wanted ad on the forums.

Let's know how you get on.

i agree over 15 years old now . i will be on the lookout for a dash same as mine then swop the clocks is that an option as it looks a bigger job still to swop .P.C.B .my email is jamesliddy@talktalk.net. if any one has a 1995 one to fit . thanks again , oilydad. i had the magnifing glass on .P.C.B. but hard to see anything wrong

The problem is,with curcuit boards, there may be another layer of ciruits imbedded in the board itself,underneath the surface layer, that may be damaged.Not shure if this is this case,i have never seen one up close.Just a thought as to why you see no damage.

You MAY be able to source a new PCB....but you'll still have to do a lot of soldering when changing everything over....Better to just find another one!! :)

There is a 940 td being broken on the auction site currently and there was one in the for sale section about a month ago.

jor

Instrument Panel
 

After reading about your problem with regards to bulbs that are not working on your instrument cluster. From my own personal experience I have had the printed circuit board go faulty on 2 of my 940's, with bulbs not lighting up. Eventually the bulb for the A.B.S LIGHT will come on and not go out which will result in an M.O.T failure. The board costs around £70.00 from Volvo, if you want advice about removing the instrument panel call me on 01793 531850
Gary