When the odometer displays no bus it means that the communication data bus has an issue and there is no communication taking place between the modules. Sometimes a module loses its ground circuit and that back-feeds a high voltage on the bus, and there are also times when a module or a wiring issue takes the bus to ground.
You'll have to measure from pin#2 of the ALDL to ground to first see if the bus is going high or low when you lose communication, and then you'll need to start taking modules off of the bus until communication is restored. When you have communication the bus voltage will read from two volts to three and a half volts.
My truck has simular problem, after a recent rain store my truck started with no problems but no gauges work and all idiot lights are lit engine runs fine but if i turn on my headlights on high beam everything goes back to normal and the no bu5 goes off and odom. works fine. I checked all of my connections and ecm and have found no visable problems all fuses are good and as long as my bright lights are on i have no problems and no codes appear.
Comments
starts minutes later
odometer reads "No bus"
Any help would be appreciated.
2001 Dodge Ram 1500 4x4
You'll have to measure from pin#2 of the ALDL to ground to first see if the bus is going high or low when you lose communication, and then you'll need to start taking modules off of the bus until communication is restored. When you have communication the bus voltage will read from two volts to three and a half volts.