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Old 05-30-2008, 01:13 PM   #1
500dollar744ti
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Default 1992+ 740/940 Instrument Cluster Repair!

http://www.turbobricks.com/maint.php?content=art0031

Note: Pics can be enlarged by clicking the thumbnail. Just so you know.

Do you have a 1991+ 740 or 940 with instrument cluster problems? The problems may be intermittent or permanent and generally appear to be electrical. Symptoms may include, but are not limited to, non-functioning gauges, warning lamps that do not light up when the car is started or the key is in position II and SRS light that stays on without throwing any codes.

If you feel your car has symptoms of this nature and you want to repair them, this article will assist in guiding you through the repair.

As a known Volvo certified technician, I've received numerous PM's asking about 1991+ instrument cluster electrical mysteries which I myself could not answer off the top of my head. I've got a long time customer that has been driving with a non-functional fuel gauge for 3 years now. I work on the car often and every time wonder why the fuel gauge and cluster warning lights act the way they do (or don't act at all).

The victim is a 1993 940 Turbo sedan with 240,000 miles on it. The car is in pristine condition and is maintained like a new born child. Ever since I started attending to this customer's vehicle, the fuel gauge has not worked and the cluster warning lamps haven't lit. Sometimes the SRS light will stay on, sometimes it won't come on at all and the only warning light to come up is for the seat belts. The customer had been quoted an exorbitant amount of money by another shop to replace the fuel tank sending unit and remedy the gauge issue. I never questioned this diagnosis because the customer was not interested in further diagnosis. However this week, I let curiosity get to me. I asked if it would be okay if I attempted to repair the cluster under the pretense that if the problem was not remedied the customer would not be charged. We told them that if the problem could be repaired we could charge a minimal amount of labor to cover it. The customer agreed and off I went on a hunch. My hunch was that, like all other Volvo electrical items, a bad solder joint was to blame. The question was just, where?

Here is the cluster showing symptoms before removal. The fuel gauge does not register and the warning lamps do not light, except for the seat belt reminder.



To remove the cluster, pop the metal trim around it out and remove the two screws securing the frame with the cluster in it. The frame and cluster can be removed together and with some careful handwork it will come out. Disconnect all of the connectors from the rear carefully and note which connector belongs in each position. Once the cluster is removed this is what you will see on the rear of it. A printed circuit board with numerous distribution strips and solder joints is present. The arrow points to the affected area which is magnified in the next picture for clarity.


If you have good eyes you may not need one but I recommend a magnifying glass to inspect the solder joints. You are looking for joints that have a break in the solder that prevents a connection from being made on the circuit board. These breaks occur from heat soak and poor solder composition as well as just plain age of components. When I removed the cluster from the 940 and examined it closely, it did not take long to identify the culprit. Here in this picture, the bad joint has been circled for identification.


What needs to be done is simple. Go around the board and reflow a small amount of fresh solder over each of the joints. There are also a few solder joints on the bottom of the circuit board so make sure to get them as well. A pencil soldering iron is all you need and can be had at Radio Shack for about $12, solder is available there as well. Wait for the soldering iron to pre-heat and then touch it lightly up to a joint while lightly touching a bit of new solder to the tip of the gun. Wait for the solder to cleanly flow over the entire joint and make a clean connection. Be careful not to bridge (let the solder expand to another joint, creating a short) any joints. You also do not want to leave a cold solder joint which is an area that is not fully heated to allow the solder to completely flow over the connection. Cold solder joints create resistance and sometimes don't make a connection at all, they also do not last as long if they work at all. After soldering all of the joints, carefully examine your work to make sure all the new solder has flowed over the joints in a clean fashion and that none of it has bridged over to any other joints that it was not supposed to. Take a picture beforehand for your own reference if you would like to see what it looked like before any repairs. This picture here shows a semi-close view of the rear part of the cluster after solder has been flowed over the joints.


Here is the picture of the previously broken solder joint after repairs. Again, a closer view and circled for identification.


So now that the repair is complete, time to test the cluster. I reinstalled the cluster and connected all of the connectors but did not screw it down in case something didn't function or wasn't connected fully. EPIC WIN! All of the cluster warning lights work and BAM gas gauge works! Sweet, I am happy, the customer is ecstatic and if you do this, you will be happy too.

EPIC WIN!
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Last edited by boostdemon; 09-07-2008 at 11:25 PM..
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Old 05-30-2008, 01:33 PM   #2
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Good deal. You would be amazed at how common the problem is.
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Old 05-30-2008, 02:40 PM   #3
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Dont forget about the built in fusible link. I just had this problem with mine and it turned out that it was indeed blown! I somehow blew it installing my ambient temp gauge. Spliced in a small legenth of copper to bypass it and all is good! Sure caused me a huge headache though.

Blown:



Fixed:

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Old 05-30-2008, 03:31 PM   #4
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^^^ yup, the fusible link will only blow if a wire shorts out or the cluster somehow shorts, happened on my 740, however you'll know if thats bad or not because it usually happens while you are messing with the cluster or trying to check signals at the wires.

this is my second article, first was megasquirt install, then this. i think the next will be 240 temp comp board fix.
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Old 05-31-2008, 01:47 PM   #5
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Good work.
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Old 05-31-2008, 03:30 PM   #6
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shouldnt the fusable link thingie be replaced with a fuse??? a wire might be a scary fuse??
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Old 06-04-2008, 02:05 PM   #7
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Quote:
Originally Posted by DaButcher View Post
shouldn't the fusible link thingie be replaced with a fuse??? a wire might be a scary fuse??

Meh, if anything shorts out, it will be the super weak little copper circuits on the circuit board. I'm not too worried
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Old 05-31-2008, 04:13 PM   #8
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Damn you did a good job. It just needs a bit o'editing for spelling and it's pretty much good to go. It'd help to sectionalize it by putting in subheads to break up the text too.
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Old 06-01-2008, 11:43 PM   #9
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^^^ i think i fixed most of the spelling... for some reason i always spell gauge incorrectly as guage.
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Old 06-04-2008, 01:51 PM   #10
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awesome dude. gonna try to do this this weekend
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Old 06-30-2008, 03:28 PM   #11
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Yesterday I noticed that when I start the car my spedo will jump from 0 to 40 and come back down to 0 again. Also while driving and coming to a full stop it will stay at like 25 or 30. And one time I was standing still at a light and it started dancing up and down randomly. And today it did that once and now its fine.

I know u didn't mention those symptoms but would my problem be similar or is it caused by something else
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Old 02-02-2009, 10:34 PM   #12
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About how long did it take for you to do this?
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Old 02-03-2009, 07:43 AM   #13
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20-30 minutes. 10 of those probably waiting for the soldering iron to pre-heat.
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Old 02-03-2009, 09:28 AM   #14
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This is good info. The only weirdness I have noticed on my '94 is sometimes when the fuel level gets to half a tank, the gauge decides the tank is full and swings over to the full mark, stays there. Also the lighting for the ambient temp is out so I can't see what the temp is at night.
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Old 02-03-2009, 12:03 PM   #15
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Quote:
Originally Posted by MrSteve View Post
This is good info. The only weirdness I have noticed on my '94 is sometimes when the fuel level gets to half a tank, the gauge decides the tank is full and swings over to the full mark, stays there. Also the lighting for the ambient temp is out so I can't see what the temp is at night.
The ambient temp gage has its own light bulb. Pull the cluster and look close.
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Old 02-03-2009, 12:53 PM   #16
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Quote:
Originally Posted by 2manyturbos View Post
The ambient temp gage has its own light bulb. Pull the cluster and look close.
Thanks. I have been too busy/lazy to pull the cluster. Now that Matt has told us how to pull it, I will get around to it soon.
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Old 02-08-2009, 03:06 PM   #17
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nice
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Old 02-25-2009, 10:51 AM   #18
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Exclamation 1985 740 turbo instrument cluster repair

I need help in repairing my cluster. temperature gauge shows spikes in electrical system like indicators ,brake lights, etc. Any tips would be nice
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Old 02-26-2009, 01:35 AM   #19
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My analogue clock is forever at 10:13. Any way to get this fixed?
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Old 04-08-2009, 10:05 AM   #20
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Im diggin up this thread because, my cousin has a 95 940 that some of the cluster lights don't come on, but if he floors the pedal they will light up and stay lit till he turns the car off, when he goes to turn it on, same thing no lights, floors the gas, lights come on...
any idea what this might be?

Also his warning light that says a bulb is burned out is forever on, but no bulbs are out, however, his car eats brake light bulbs...
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Old 07-10-2009, 04:17 PM   #21
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Im diggin up this thread because, my cousin has a 95 940 that some of the cluster lights don't come on, but if he floors the pedal they will light up and stay lit till he turns the car off, when he goes to turn it on, same thing no lights, floors the gas, lights come on...
any idea what this might be?
gaspedal assembly hitting a hanging part of the wiring loom ?

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Also his warning light that says a bulb is burned out is forever on, but no bulbs are out, however, his car eats brake light bulbs...
is he using the correct wattage bulbs in the brakelights?
my 940 has a 3rd brakelight and i have installed an additional brakelight in the spoiler. I hooked it up to one of the existing brakelights and now every time i brake the yellow bulb failure light comes on. in other words: the error light is sensitive to how many and what kind of bukbs you install.
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Old 07-14-2009, 02:50 PM   #22
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Quote:
Originally Posted by Janspeed View Post
gaspedal assembly hitting a hanging part of the wiring loom ?



is he using the correct wattage bulbs in the brakelights?
my 940 has a 3rd brakelight and i have installed an additional brakelight in the spoiler. I hooked it up to one of the existing brakelights and now every time i brake the yellow bulb failure light comes on. in other words: the error light is sensitive to how many and what kind of bukbs you install.
i have the same setup: third brake light + a honda prelude spoiler with a diode brake light.
I sometimes get these "bulb out" warnings for a few pushes of the brake pedal once in a while.
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Old 07-24-2009, 02:23 PM   #23
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The bulb-failure warning device works on the resistance in the circuit, lighting the warning bulb when the preset resistance is not met or exceeded.
You could try using a small relay to switch the extra brake light bulb, taking power from a separate fused circuit.
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Old 04-12-2009, 05:59 AM   #24
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sounds like a bad alternator, at least in a 240.
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Old 04-19-2009, 09:23 PM   #25
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yes
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