940 Volvo Speed Sensor Cause Not to Read Speed

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A vehicle speed sensor, or VSS, is a sensor that is used to make up one's mind how fast your vehicle is traveling. If your vehicle'due south speedometer stops working or isn't telling you the correct speed that you're traveling, yous likely have a faulty VSS. You can test your VSS to brand sure information technology'southward operation properly past using a device chosen a multimeter. Kickoff by disconnecting and removing the VSS from your engine so yous can test it. You can then connect it to a multimeter and set the multimeter to the AC setting. Connect the VSS to a power drill so you can simulate the rotation of the vehicle'southward transmission and read the multimeter to meet if the voltage increases as the speed increases to check if the sensor is working properly.

1. one

   Make sure the vehicle is turned off to avoid being shocked. Put the vehicle in park on level basis and turn off any lights or accessories that may draw ability from the battery. Remove the key from the engine to brand sure information technology'due south completely turned off.^[1]

   • Parking on level ground makes it easier for you to admission the VSS.

2. ii

   Open the hood of the vehicle and so you can access the engine. Locate and pull the release hatch most the commuter's side door to open the hood. Engage the interior release hatch on the front of your hood and raise the hood up. If your hood uses a rod to hold information technology open, motility the rod to its slot.^[2]

   • Make sure the hood is held securely in place earlier you lean into it to examination the VSS.

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3. 3

   Locate the VSS sensor most the transmission of your vehicle. Detect the transmission dipstick and follow information technology to locate your transmission. The VSS will be a small sensor attached to your manual by 2 wires and held in place by a bracket. It will also have a sliding pull tab on information technology. Await for a small, metal sensor surrounded by a metal bracket with a white and black wire continued to it.^[3]

   • Vehicle speed sensors can be installed in different locations depending on what make and model of vehicle y'all have, but they mensurate the rotation of the manual, so they'll mostly be located on or next to the transmission.
   • Consult your possessor's manual to find the location of your VSS.

   Tip: If yous don't accept your owner'south manual, or you're unable to find your vehicle'southward VSS, search the brand and model of your vehicle online to locate the VSS.

4. 4

   Disengage the wiring harness connector from the VSS. There are 2 wires connected to the VSS, a blackness 1 and a white 1. Both wires connect the VSS to your vehicle to basis the sensor and transmit data about you're vehicle'due south speed. Unplug the harness then you can have out the sensor.^[iv]

   • The wiring harness may be located on the underside of the VSS.
   • If you can't grip the harness with your fingers, use a pair of needle-olfactory organ pliers to disengage it.

5. 5

   Printing the pull tab or button on the VSS to carve up it. On the top or side of your VSS will be a sliding tab or a button. Engage the tab or push button and gently pull on the sensor to release it from its housing.^[5]

   • You may need to wiggle or slide the VSS out of its base.
   • Don't forcefulness or yank the VSS or you lot could damage it. Brand certain y'all've engaged the sliding tab or the push button that releases information technology.
   • Some sensors may crave you to remove 2 small screws to slide it out of place.

6. 6

   Unscrew the concord-down bolt and bracket to remove the VSS. Use a screwdriver to remove the bracket around the VSS. And so, use a socket wrench with a slice that fits over the bolt to twist the bolt and loosen it and then you can pull out the sensor.^[6]

   • Brand sure y'all don't lose the screws or bolts so you can replace the sensor.

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1. 1

   Plug the colored lead cables into their slots on the multimeter. Your multimeter volition take a carmine and a black lead cable. Plug the black lead into the blackness colored terminal that's labeled "COM" which stands for common. And so, insert the crimson lead into the red colored terminal labeled "V" for voltage, which is what yous're testing.^[7]

   • Push the leads into their slots completely. They may "click" into identify when they're fully connected.

2. 2

   Prepare the multimeter to AC to examination your VSS. Wait for a dial on your multimeter that has numbers and letters on it. The Air-conditioning, or alternating current, setting may exist labeled as Ac, 5 with a squiggly line, or ACV. Plough the dial until the arrow or indicating line is pointing to the Air conditioning setting.^[8]

   • Electrical devices, such as your VSS, apply an Air-conditioning current for power.

3. iii

   Plug a point output and ground wire into the sensor. On the VSS is a slot where the sensor plugs into the vehicle. You can find a plug that fits into your VSS and contains a white signal output wire and black ground wire from auto supply stores. Make certain the plug fits your VSS securely.^[nine]

   • The plug uses a white indicate output wire and a blackness ground wire to transmit signals from the device to your vehicle.
   • Y'all can too find plugs that contain the signal wire and ground online.

4. 4

   Connect the black lead and the red lead to wires on the plug. Have your black pb wire and clip it to the exposed wire at the terminate of the blackness basis wire plugged into the VSS. And so, have your ruby lead wire and connect information technology to the exposed end of the white point wire plugged into the sensor.^[10]

   • Make sure the red and blackness leads are securely connected.

   Tip: If the bespeak wire and ground wire are completely covered in sheathing, apply a knife to strip about ¹⁄_iv inch (0.64 cm) of the wire sheathing to betrayal the wire beneath then y'all tin can clip your leads to it.

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1. 1

   Find a drill chip that fits securely into the VSS. In club to simulate the movement of your vehicle to properly test the sensor, you demand to rotate the gear inside of the VSS. Insert drill bits into the gear slot on the VSS until y'all detect one that fits securely into it.^[xi]

   • Different sensors have differently sized slots, and then endeavor out a few bits until you find one that fits your VSS.

2. 2

   Connect the fleck to your power drill. Loosen the chuck, or the piece on the end of the drill, by rotating it so the jaws open upward. Slide the polish stop of the scrap into the jaws and so slowly rotate the drill to tighten the jaws around the bit so information technology's held deeply.^[12]

   • Requite the bit a gentle tug to make certain it won't fall out.

3. three

   Spin the gears of the VSS by pulling the trigger on the drill. Agree the VSS in identify with your hand and bring the drill up to speed slowly to rotate the gears in the slot the drill bit is inserted into. Allow the VSS to rotate at full speed so you can get an accurate reading.^[13]

   • Start slowly and continue to increase the speed of the drill at a consequent stride then you don't strip or damage the VSS.

4. 4

   Read the voltage on the multimeter to see if it increases with speed. While the VSS rotates, the multimeter will brandish a voltage reading. If the VSS is functioning correctly, the voltage on the multimeter volition increase as the speed of the VSS rotation increases.^[14]

   • If the voltage doesn't increase or doesn't display at all, then the VSS is damaged or faulty.

   Tip: Rotate the VSS at varying speeds to make sure the multimeter is accurately detecting speed changes.

5. 5

   Disconnect the plug and drill, and reinstall the VSS into your vehicle. Remove the drill bit from the VSS and take out the plug containing the white point output and black basis wires. If the VSS is functioning properly, slide it back into its housing, reconnect the wiring harness, and replace the bracket and bolts.^[xv]

   • If your VSS isn't performance properly, supersede it with the aforementioned make and model so it fits into your vehicle.
   • Take a mechanic inspect your vehicle if your VSS is functioning just your speedometer still isn't working properly.

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Things You'll Need

• Multimeter
• Screwdriver
• Socket wrench
• Signal output and ground wire plug
• Power drill
• Drill bit

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Source: https://www.wikihow.com/Test-a-Vehicle-Speed-Sensor-with-a-Multimeter

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