Book says:"is the ecu connector c750 properly connected? "This is the metal box that is mounted to the back panel of the engine compartment. Check the left hand plug. Clean pins and check for broken wires where the pin and the wire connect. We had a problem with oil pressure light on our 9510 and it was a broken wire at the tiny pins in those connectors. Back to our project, If the plugs and the connections are good , It says to refer to the schematic and repair cc#132 (which is wire marked #132) it is in the engine, r.h. main and cab harness. Alot of wire tracing if your problem is not at the ecu connector. Both of our wiring problems were wires broken at the back of the pin connectors. Took me nearly a week to trace down both of our wiring problems.