Speedometer stopped--86/760 Turbo

[CFSEnterprises]

Bought a 1986 760 Turbo in fantastic condition....runs great, very well maintained.

Have two puzzling problems:

1. The speedometer just stopped working....I understand it's electrical....where is the fuse? relay? Don't know where to look, start. Help!!!

2. The fuel guage was going up and then down and then nothing at all...
it would flip from full to empty rapidly and then when the speedometer quit working it stopped flipping at all.....any ideas? Where to begin

If there is anyone out there that can get me to the information on how to fix these problems or can help me please contact me at [email protected] or call me on my toll free number...1-877-885-3868.

Thanks,

Chuck Shadduck

[Tore]

The speedometer and possibly also the fuel gauge has electrolytic capacitors which may break open with age. The speedometer then will not work but the capacitors may be replaced. The electrolyte may be washed off the board with distilled water. Here are the steps. Remove the instrument cluster. Remove the speedometer from the instrument cluster. Do not break any of the little stop posts. Remove the speedometer needle by twisting in the backwards (CCW) direction. It will not come off with a straight pull. Then remove the board and the odometer motor. Make a diagram of all electrolytic capacitors, noting their polarity. On my 1991 740 there were 6. Remove them with a soldering iron and a popping syringe type solder sucker. Replacements can be ordered from Mouser electronics. Observe polarity, temperature ratings (105 C), voltage rating and capacity in microfarads. Of the six capacitors, two of them were replaced with tantalum capacitors of the same rating. Solder back in. The needle goes back on at about the -5 to -7 mph position. Check the speedometer with a sine wave generator if you have one available. I put the needle back at about the -7 mph position and it checked 40 mph at a true 38.3 mph. Close enough.

[Speedwagon]

Bump for an old thread from the grave!

So I just picked up a 240DL last night. Speedo and odometer don't work. I know the speedo is capable of working though. Was looking behind the instrument cluster, and found a loose white/pink wire. Hooked that up to the one tab I saw loose on the back of the unit. This made the engine not start(just cranked), but the speedo needle slowly rose. Is this wire just supposed to be hanging back there?

I'm guessing since it's an electrical unit, and neither the speedo/odo work, that it must be the sending unit. Where are these located in a Volvo 240? In/on the trans, or the diff?

[LaRy]

I suppose that the fuel gauge and speedometer problem starteded for you at the same time. Don't you have problems with the temp gauge? All these 3 components have one unit in common, feeding is coming from a voltage stabilisator placed close to these units.
Either the voltage stabilisator is broken or the ground is bad. Check the ground distributer rail in the right footwell, placed behind the panel in front of the door, 4 inches above the floor. Check all the flat AMP connectors. Actually if you hit the panel by your foot, the ground connection is so close behind, the it can make some connectors loose. Check also all connections in the back of the dashboard. Most probably you have a bad ground or voltage feeding.

The voltage stabilisator is reliable, but the speedometer PC board has some well known elctrical problems, the capacitor but also some IC-unit is getting mechanicly cracked after all these years. If you can make the speedometer work by knocking hard on the upper side of the dashboard when driving, you have a broken IC-circuit. It is so common, that in Sweden were I live and Volvo is very common, some companies replace your speedometer with used one, the PC board is updated with new capacitors and IC circuit.
But as I said in the beginning, if speedometer, temp gauge and fule gauge are having problems at the same time, ckeck the ground and voltage stabilisator. Just remember that if you take the dashboard out, it is a good idea to make some notes and small drawings about the connections, to avoid new problems when putting it back.

[LaRy]

Reply to the 240DL problem. Is it a diesel made after 1990? Then it could be the wire that is going to the glow plug indication light bulb. In some 240's this wire is white-pink. If you are connecting this to the wrong place, maybe the glowplug system does not work and the diesel does not start.

[Guest]

No, it's an '87 gasoline 240DL.