Peterbilt Speedometer And Tach Not Working - I have a 90 that had the same problems with tach and speedo. If you wiggle the wire plug on the back they come back to life if held in the right position. I ended up having to take. We have noticed that the tachometer doesn't work at all and it looks like they just replaced it with a brand new one. I pulled the dash panel out (which i love how easy that is to. It shows miles when the key is off but gives lines when key is turned on. Sometimes the end of the sensor can get chipped off and not work anymore. If it needs a new sensor, clean the threads in bellhousing with a tap. Screw sensor in until it. All of a sudden both went down. The tach is buried straight down between 0 & 30. My speedo is just under the 0 and they don't move when i turn the. The most common issue with the dixson 900 series analog peterbilt 379 speedometer is the odometer mileage stops and/or the speedometer needle stops working. This failure may be. Having an issue with a speedometer on a 2025 389. Speedometer has power and sweeps on initial key on but does not read speed. Both speed sensors are working correctly. You'll be best off to open the dash and access the back of the tach with a tester to check for continuity back to the sending unit first, to see if the wires are ok. At that point if they. I've got a 90 and had lots of problems with the plugs going into the back of the gauges.
I have a 90 that had the same problems with tach and speedo. If you wiggle the wire plug on the back they come back to life if held in the right position. I ended up having to take. We have noticed that the tachometer doesn't work at all and it looks like they just replaced it with a brand new one. I pulled the dash panel out (which i love how easy that is to.