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Volvo 240 86-93 speedometer replacement for odometer/speedometer electrical issues
Volvo 240 speedometer/odometer circuit board replacement 86-93
Tools: Phillips screwdriver, flatblade (I use a butter knife) to remove plastic, soldering iron, solder removal items (wick, solder pump, or both), and solder.
Board numbers used:
VDO- 992645 145 (does not have connections for the cruise control board). Picture below with the wires cut but attached.
VDO- 992645 734 Cruise control capable board (Note the red circles showing the solder joints)
Removal: The procedure getting to the speedometer board is the same procedure as replacing the odometer gears, but with the addition of removing the board. With the speedometer board hanging down, take your soldering iron and desolder the black and blue wires, keeping careful note about where they go. It is always a good idea to mark wire locations with a sharpie marker or take lots of photos.
NOTE: If you have the Cruise Control board, desolder the two brown wires. NOTE that one has a red stripe down the side, making it your positive lead. Be sure to mark this.
Once all wires are removed, install the new board in reverse. Make sure to not hold the soldering iron too long in any location and to create good clean solder joints. There are many online tutorials on YouTube about proper soldering.
NOTE: If you did not replace the center (larger) gear, make sure there is no sticky residue on the gear. If so, spray it with contact cleaner or dip it (gently) in lighter fluid, and allow to air dry. Do not “dab dry” or touch the rubber gear teeth. Also look for pieces of broken gear just in case something was missed.
Reinstall: After soldering, install the odometer gears and reattach the board. Assembly will be the same procedure as if you were just replacing the gears. A common issue with speedometer damage is caused by the tachometer wire being connected (accidentally) to the cruise control taxi. Make sure to leave the Red/White wire alone if you do not have a tachometer. Many shops see this orphaned wire and hook it up to what appears to be the right location, causing damage.
Make sure before attempting any long drives that the speedometer is working correctly. When getting a used board from a yard, there is always risk of an issue.
If I was unclear on something please let me know! I struggled for years to get my odometer actually working and was told online there was nothing to do but replace the whole unit. Even my local Volvo dealer said that was all I could do besides giving up like many people.
Anyways, enjoy your tracked miles!