Originally Posted by
Jack G
Pizza guy in regard to the input pulses or data points to the odometer, is this data generated by an optical encoder driven somewhere off the transmission output shaft? If it is and it is operating erratically this could be affecting the distance data input to the odometer. If 9mpg is real where is all the fuel going? It almost seems like the exhaust system should be operating like an after burner on a gas turbine engine.
No, that whole thing about driving a speedometer by a sensor/cable on the output of the transmission is "old school", not "R170" at all.
There is a wheel speed sensor at each wheel. All four of them report to the CAB (Controller-Antilock Brake), that is, the brake controller. The CAB then sends
front wheel speed sensor data only to the Instrument cluster on CAN BUS C, the cluster then uses this data to drive the speedometer and odometer. (The data is also sent to the TCU [automatics only] and PCM/ECM, but not for the purpose we are talking about here.) If the speedometer is accurate, the data is accurate.
I agree, 9mpg sounds nuts, but again, I have seen my SE go down into the 12-14mpg range when driven hard on, say, the Dragon (hey, it takes a lot to keep up with SRTs!) It just seems to me, as has been mentioned before, the plugs and exhaust tips should show a lot of carbon buildup.