How to Troubleshoot a VDO Electronic Speedometer
By Breann Kanobi
The VDO speedometer interfaces with the gauges and senders of your vehicle in order to properly display speed. You can determine any problems with your speedometer using an ohm meter. When using an ohm meter you work with electric parts. To keep yourself safe during this task, wear rubber-soled shoes and double check each wire you intend to touch before you touch it. Keep your engine off during the process.
Rewire the sender. Gently pull each wire from the sender and insert the wires into their appropriate slots. The red sender should connect to the #2 terminal of the speedometer. The black wire of the sender should connect to the #3 terminal of the ground. The white sender should connect to both terminal #6 and #8. The 12-volt switch should connect to the #4 terminal.
Insert the key into your automobile ignition and turn the car to the "On" position. The pressure gauge should be at "0." Grasp the wire of the speedometer sender and look at the gauges. The fuel gauge and pressure gauge should move to the right-most position. The temperature gauge should move to the left-most position. Touch the wire to the chassis of your automobile's engine. The pressure and fuel gauges should move to the left-most position. The temperature gauge should move to the right-most position. If the gauges do not respond as they should, your problem lies with the gauges.
Hold an ohm meter near the sender terminal. Touch the positive lead of the ohm meter to the cold temperature sender terminal. Touch the negative lead of the terminal to a ground. It should read "- 700 ohms." Touch the positive lead to the pressure sender. The ohm meter should read "- 10 ohms." This tests the temperature and pressure senders.
Touch the positive wire of the ohm meter to the fuel sender. If your tank is empty, the ohm meter will display a number around 10. If the tank is full, the ohm meter will display a number around 180. A partially full tank should display a number in between. If the readings you see are different from the expected readings, your problem lies with the fuel sender.
Reprogram the VDO. Press and hold the "In" button of the device and start your automobile. Press the device's button until you see the screen display "AUtOCL." Watch the screen until it displays "bUttOn." Drive exactly 1 mile and press the button of the device. Drive exactly 1 mile and press the button on the front of the VDO.
Breann Kanobi has worked as freelance writer since 2010. Kanobi regularly submits content online to Gamer DNA. Kanobi received a Bachelor of Fine Arts in film and television from New York University in 2010.