My wife's 1993 940 wagon (automatic trans) has a bunch of instrument cluster related problems. It started 2 years ago when the speedo went out. I got a replacement cluster off eBay and all was fine. Then about a year ago (I'm slow sometimes) the speedo went out again. This time the tach, gas gauge, cruise control no longer work and a bunch of instrument panel indicator lights appear to not function. The clock, turn signals and instrument panel lighting still work.

When you turn the car on the OD light comes on, the seat belt warning light comes on (if you don't have on a seat belt) and the instrument cluster backlights come on. When you start the car the temp gauge comes to life and the OD light stays on. If you press the OD switch on the shift lever the OD light goes out AND the temp gauge quits. The OD light must be on for the car to shift normally (which used not to be the case before these problems).

I have reseated all the connectors on the instrument cluster and checked the ground behind the driver's kick panel. I have wiggled all the relays in the fuse panel area and pulled the OD relay out of it's case and all looks good but STILL NO:

Speedo
Tach
Gas Gauge
Cruise Control

HELP!!! The wife wants to get a Honda but I can't stand the thought of a FWD car...

Wow,
This problem is very detailed and complex. Some thoughts: you might have a short some where, but a good start would probably be to get some contact cleaner/lubricant spray (about $12 at Radio Shack), apply it to any electrical connections, following the intructions on the can, and see where that gets you. This spray is always good to have around on any older Volvo(or car). But since it is a reoccuring problem it may be the computer, although you made it a year without problems. Many post's can be found here on that subject. I see you got many replies on the cluster micro film, that was the most important idea of mine, and most likely your culprit.

Good luck and sorry can't be of more help,
Mitch

93 850, the rest are gone(93 940, 96 850, 93 850 parts car)

Volvo dealers can supply a new flex film circuit panel on the back of the cluster: try Borton Volvo or Tasca Volvo. Not cheap but it will likely fix your problem.
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See the 700/900 FAQ at the drop-down menu above right.

the thin film on the back of the cluster is fragile and in fact a circuit board. it may have degraded to the point numerous pathways are broken and or shorted out.

i would swap in a known good cluster to see if an entire cluster makes an immediate difference.

93 or 94 940 or 960 ones are the only compatible units

if you get jammed let me know as i have two both from 93 940's. one a wagon one a sedan BOTH non turbo

try here

http://www.car-part.com

for a large assortment of clusters

Thanks for the response!

Known good cluster... All I have is the old one in pieces and the currently installed one which may have lots of problems. I guess I will take both to the bench and start comparing/testing.

Since so many things went out at once I was thinking/hoping it might be something outside of the cluster. However the ground is good and +12VDC appears to be good.

Do you have any idea what the small 4 legged circuit on the upper driver's side does? Voltage regulator?

Any ideas on where can I find a better wiring diagram than in Chiltons?

email me privately as i have all factory wiring diagrams/green manuals for 940's.

specifically i have the full mitchell wiring diags for the 93 940 and the volvo green manual for ALL wiring for the 94 940 (which is nearly the same as the 93)

it may be time to mix and match the 2 clusters. what exactly failed on the old cluster?

ie: if the tach also failed on the old cluster your problem is likely not in the cluster. tachs are quite robust. i have never heard of 2 failing.

FIXED!

It has been REALLY cold here so I didn't get around to probing with a good wiring diagram until yesterday. Armed with a decent diagram from trichard, the old cluster and my handy Fluke 77 the gremlins didn't stand a chance...

It turns out that there were two problems, both related to the flexible PC board on the back of the cluster.

First was a fuseable link located above connector A and slightly to the drivers side of the cluster. Bridging the gap the meter indicated 1 amp so I put a 2 amp fuse across the burned out link. I used a fuse that has wire leads and simply used two screws into the existing holes to make the connection.

With that done the entire cluster came to life minus the fuel gauge. The check on that is:

bottom hole - fuel sender resistance. In my case around 40 ohms. OK!

drivers side top hole - 0 ohms to ground. OK!

passenger side top hole - +12VDC. NOTHING! This is fed by the previously fixed fuseable link so tracing the path on the PC board yields a poor solder connection right below the E connector. Touch it with a soldering iron and some solder and FIXED!

So now everything works and is mostly put back together except I have not snapped in the instrument cluster bezel just in case the fuse decides to pop. A copy of the wiring diagram is in the glove box along with a spare fuse. If the cluster makes it a month or so without problems the bezel gets snapped back in.

Thanks so much for the help!

Hey, can you go over that gas-gauge fix again?
My '94 940 gas gauge has not worked properly since I
bought the car -- no reading. I replaced the entire cluster
with one I bought on ebay and for the last two years it has
worked on and off. If I really need to know the gas level
I slap the dash hard just above the gas gauge and usually
it'll turn on 'til the next big bump in the road (in chicago
there's lots of 'em). I've reseated all the connectors,
but never gone further... anyone got any bright Ideas?

I had the fuel gauge problem in my daughter's car when we
purchased it two years ago. I would hit the dash and some
times get the gauge to work for a short while.

My first repair attempt was to remove the screws in the
back of the gauge and add brass washers that I soldered
to the circuit board. This was delicate since I did not
wish to damage the polyimide circuit board, and also had
to get the holes lined up correctly. I will not go into
any detail here since this did not work. But the idea
was to give the screws some soft solder to sink into.

What finally did work on my third attempt was the "Don
Foster" approach to resolder. Take a look at the article
over at http://www.turbobricks.com/maint.php?content=art0031.
There was one joint that had a bad solder joint causing
intermittent contact.

In my case the bad solder joint was not the one circled, but
next to the far left screw. http://www.turbobricks.com/maintenance/img/art0031_img004.jpg

I heated up the solder till it reflowed, and have had a rock
solid fuel indication since. Just be careful soldering to the
flexible circuit board. I used a small 27 watt iron, and took
my time. Too much heat to quickly can kill the board.

Donald E Booth

1993 245, B230F, AW70, 154000 miles
1993 945, B23oT, AW71, 118000 miles

Gone but not forgotten

1991 245, B230F, M47, 118000 miles
1984 245, B32F, M46, 286000 miles

People tell me that Volvo is Latin for "Mass in Motion".
I believe it's actually French for "Bad Solder Joints".
The units comprising the dash display, and the plugs are, in my experience, pretty reliable.
The problem is bad or cold solder joints. I've had issues even with "reflowing" the solder. I've gotten good results with removing bad solder with a solder sucker and reapplying using Ersin Multicore or perhaps military circuit board solder, if you can get it. It should be kind of skinny, not like fat pipe solder. The kind of solder you're looking for is "eutectic", that is, it goes from liquid to solid without a plastic state in between. You'll know this solder because it will be something like 63% lead, 37% tin, or similar. (Not 60/40, like most cheap circuit board solder.) If it's got 1% copper, you know you've got some of the best. You want to use a temperature controlled iron, 700F degrees is effective. Keep the tip of the iron clean with a damp (water) sponge, and tin it before you apply heat. Try to heat both metal parts at the same time, then apply the solder to the tip of the iron and both parts equally. That should get you a good joint. Eutectic solder will "freeze" instantly, so you won't get what's referred to as a "cold" joint that's high electrical resistance.
Be cautious not to overheat the flex, because it will cause the trace to come unglued. If you do have a damaged flex, get a small piece of skinny wire (24 gauge stranded is ideal), and jumper over the bad part of the flex from one soldered joint to another, soldering only at the ends to minimize heat on the flex.
I believe it's advisable to solder every single joint on the flex, systematically. Remember, Volvo is French for "Bad Solder Joints". (P.S., You can fix the intermittent stereo and small relays the same way.)