My service engine light is on combined with a blinking cruise control light. Also, my cruise control does not currently function.
The diagnostic code is P0851 - Neutral swith input circuit, low voltage. One of the listed probable causes is a failed neutral switch, so I thought I would start there. The Haynes repair manual references the the NSS for the manual transmission, but not the automatic.
I recently bought the OB, so I am unfamiliar with the vehicle. Any help is appreciated.
My 07 service manual lists two P0851 codes, one for MTs and one for ATs. They are essentially the same.
They indicate that there's a ground, or a malfunction in the relevant switch circuit to the ECM.
In the AT, normally, when the gear shift lever and the Inhibitor Switch are in P or N, the Switch connects the starter relay to the starter solenoid. (See attached diag.) When the ignition switch is turned to Start, 12V is passed through the relay and through the Inhibitor Switch to the starter solenoid.
When the gear shift lever and Inhibitor Switch are in any other position, pin C31 should be "high"; in other words, there should be no continuity from C31 to ground. The ECM compares the voltage at C31 with signals coming from the TCM corresponding to which gear it is actually in, and if it finds that C31 is Low while the transmission is in anything other than P or N, it triggers the DTC. (As with the NSS, the purpose is to prevent the starter from running when the transmission is in any gear other than P or N.)
The cause of the DTC might be a problem in the wiring between the ECM and the Inhibitor Switch, or in the Inhibitor Switch, that is keeping pin C31 low, even when the transmission is not in P or N. (It could be just a misadjustment of the Inhibitor Switch or it's connecting cable, that is allowing the switch to maintain the N connection when the lever is in R or D. But this will require some direct measurements to confirm and correct.)