Hi kevtwad,
This means that the hr meter MDI is in conflict with controller unit in that the truck may have had anew controller fit and the MDI will show you that code denoting that the hr memory will be a eraised in sixty seconds with traction inhibited. If you know for a fact a new combi controller has not been fit, then it's more than likely that the multi pin connector in the MDI gauge has come loose and when the truck goes over a bump the connector makes and breakes putting the MDI into conflict with the combi controller, switch the truck of and make sure the connector is firmly inserted in the MDI gauge. Switch the truck back on do not drive the truck, the MDI will flash for 60 secondsu will be able to drive the truck. and the hrs will then be displayed and yo