Usual 1998 Chevy Silverado Speedometer Problems: How to Fix?

1998 Chevy Silverado speedometer can give you faulty speed reading. This can due to several reasons for example your vehicle wheel/tires are not of recommended size, vehicle engine control unit ECU is defective, Speedometer wire is broken or your vehicle speed sensor is not working properly. What ever the reason is, there is a complete solution for it.

The speedometer in 98 Silverado is a vital part that reads the actual speed of your car in MPH. Due to some reasons, this speedometer can refuse to show the right MPH reading.

Some of the reasons that can cause 1998 Chevy Silverado speedometer problems includes,

  1. Different size wheels being used than the recommended size
  2. Engine control module/Unit (ECM/ECU) failure
  3. Speedometer wiring issue
  4. Broken vehicle speed sensor VSS

In order to fix the bugs, you might need to attach the correct size wheels then calibrate the speedo, reset ECM/ECU, replace the wire of speedo, and change the VSS.

Keep on reading to know the in-depth procedure of fixing the speedometer bugs!

Usual 1998 Chevy Silverado Speedometer Problems: How to Fix?

1998 Chevy Silverado Speedometer Problems, Causes & Fixes!

If your car is suffering from speedo issues, then this article will let you know about each kind of issue, its cause, and how to solutions that issue.

Problem #1: Speedometer Reads Slower / Higher Than Actual Speed

Speedo indicator needle sometimes shows 40 MPH while you are going at 60 MPH or 60 MPH when you are going 40 MPH. This mostly happens when you recently change wheels or tires and then calibrate to get the accuracy. If wheel are bigger or shorter than recommended size then speedometer will show wrong reading.

How To Troubleshoot?

  1. Check the door jamb to know the right size wheels or tires that you need to put on. Take out the wheels or tires and insert the new ones. Be sure to calibrate the speedometer after attaching the wheels or tires by doing the following steps.
  2. Use a speedometer calibrator tool and connect the plug to the laptop and inline module. Just enter the new and old tire size details which you have inserted into the car.
  3. Find the On-board diagnostics OBD II port (under the driver’s side) and detach the white conductor. Insert the OBD II plug (that comes with the speedometer calibrator tool) on the white conductor and another side on the inner module.
  4. Hit the calibration button on the speedometer and turn your car on. Release the button.
  5. Press the same button again.
  6. Then, test-drive the vehicle for 5 to 10 minutes.

Problem #2: Speedometer Stop Working & Activate Check Engine Light

A lot of times the speedometer doesn’t work or stays in one specific position while the CEL (Check Engine Light) or SES (Service Engine Soon) lights turn on. If that ever happens to you, the culprit is none but the ECM failure.

How To Troubleshoot?

  1. Open the hood.
  2. Locate the battery compartment in the top section.
  3. Remove the cover of the battery.
  4. Take out the negative wire and then the positive wire.
  5. Let them sit on a rag or cloth to avoid electric issues.
  6. Briefly attach them together to drain or discharge all capacitors.
  7. Then, wait for a while.
  8. Connect the negative wire to the negative terminal and then the positive wire to the positive terminal.
  9. Done!

Note: If you smell something frying, then, it’s best to call an expert to do the ECM reset or replace the unit.

Problem #3: Speedometer Can’t Move According to Speed

When the speedo can’t be able to settle or move according to the actual speed of your vehicle, this might be indicating a wiring issue. The indicator needle might jerk or bounce back but read wrongly.

How To Troubleshoot?

  1. Wear electrical gloves and turn your vehicle off.
  2. Open the hood.
  3. Locate the engine.
  4. Remove the engine cover using a proper tool (if you have to unbolt some screws).
  5. Inspect the cabling to understand where it enters the main body of your car.
  6. Locate the thick black wire that goes to the instrumental panel. This wire is the speedometer cable of your car.
  7. Take out the screw under the dash using a screwdriver. Find the thick black cable and detach it.
  8. Detach the nut on the transmission and pull out the cable if you can.
  9. Unplug the clamps on the transmission and the engine bar which holds the speedometer cable.
  10. Clean a little using a small brush.
  11. After removing the thick black wire, insert the new cable by doing the opposite of removal.
  12. Reinstall all the parts.

Problem #4: Speedometer Read Too Fast or Too Slow

The 1998 Chevy Silverado speedometer too fast or slow is a real issue that occurs when the VSS (Vehicle Speed Sensor) turns bad. It is not able to send the signals to the computer (VCM) to process and give the correct input to the speedo.

How To Fix?

Replace The VSS From FWD (Front Wheel Drive):

  1. Open the hood of your car.
  2. Locate the engine compartment on the front side.
  3. Find the speed sensor (behind the engine, above the transaxle).
  4. Take out the hose, air cleaner, and connector (on top of the sensor).
  5. Detach the screws that hold the speed sensor in place.
  6. Remove the speed sensor by twisting it in the anticlockwise direction. Be sure to detach the O ring and other things.
  7. Clean the flange and housing.
  8. Insert a new O ring and a speed sensor.
  9. Reinstall all the parts back to their place.

Replace The VSS From RWD (Rear Wheel Drive):

  1. Open the front trunk.
  2. Locate the speed sensor behind the transmission on the driver’s side.
  3. Lift the vehicle by using jack stands.
  4. Remove the wheels using the proper tool.
  5. Detach the connectors above the sensor.
  6. Then, take out the screws using a wrench.
  7. Unplug the speed sensor by twisting and detaching the O ring.
  8. Insert a new O ring and speed sensor into the right place.
  9. Put on all the parts by doing the opposite of the removal procedure.

Also Read: 1997 GMC Sierra Speedometer Problems And Causes!

Overall Thoughts

If in the future you face the 1998 Chevy Silverado speedometer problems like right now, try the given solutions based on the causes.

Yes, you might need to spend bucks to grab new gear if parts need replacement. And it’s all okay to change the problematic components via a skilled person if you have sufficient money in your pocket. 

Hope you like this guide and get the needed information that helps. Bye, For Now!

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William Baldwin

This Is William Baldwin, The Founder & Managing Editor of this website. Me and my team share automotive tips, tricks, and news