Q: Speedometer jumps up/down and van backfires. 1998 GMC Savana

asked by on

The speedometer in my van jumps up and down. The radio volume drops to almost nothing when it goes to 40 and then to 100. Plus, the van started backfiring when the engine is slightly cold and I’m pulling out. I took it to a professional auto shop and they worked on the temperature gauge, but it did not make any improvement in the speedometer problem. They even replaced it and the same thing is happening. Then they installed a Cam sensor and it stopped backfiring until today. Now it is backfiring again. Hundreds of dollars in repairs and the only thing working is the temperature guage! What will fix my van’s speedometer and backfiring problems?

Hi there, thanks for writing in about your 1998 GMC Savana 2500. The speedometer and radio may work together to adjust volume of the radio as the speed increases. The cluster or any of the affected modules may have a connector issue from fretting corrosion in the connectors. I would suggest disconnecting the battery and disconnecting the connectors to the engine control module, body control module, and the instrument cluster to look for corrosion and clean and apply dielectric lube to the pins and lightly seal and reinstall to make sure connections are secure. If you need further assistance, a certified technician from YourMechanic can come to your car’s location to inspect the speedometer and let you know what should be repaired.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Speedometer jumps up/down and van backfires. 1998 GMC Savana

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Q: Speedometer broke.

Hello, to check the operation of the speedometer, a scan tool needs to be connected to monitor the speed sensor output and see if it has any output, and if it is smooth. You will probably need the aid of...

Q: Will the gaslight still come on if the gauges are not working on my car

The low fuel light is incorporated into the gas gauge cluster and I will only speculate that if the gauge is not working then most likely the low fuel light will not come on. The light usually comes on when...

Q: Battery replaced, engine malfunction warning

Hello there. With any Check Engine Light, the first step is to have the code read to determine what system is involved with the fault. It is possible that this fault was caused by the vehicle losing power when the...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...