360 throwing a code of 1790

Hi gal,

See the attached 430 Fault Code list (thanks, Marti). For code P1790, the malfunction source is: “CLUTCH POSITION PRIMARY_VAC SENSOR”. The malfunction description is: “Primary signal for clutch position sensor out of range. Possible failure either in the sensor primary or in the ECU internal.” The malfunction type is “DEFECTIVE SIGNAL”. The diagnostics procedure is to “Check the wiring on Pin 34 (primary output 1) and Pin 35 (secondary input 1) / component intactness.

There is a small magnet mounted to the throw-out bearing and the clutch sensor renders a signal from the magnet’s position in relation to the sensor. The fault code implies that the magnet is out of the range that the ECU expects from the sensor signal. This means that the sensor could be loose, gone or defective, the magnet could be loose or gone or the position sensor wiring could be loose or disconnected. There could also be a fault with the ECU but this is not likely. It would be more likely that you would have much more severe problems with the car with a bad ECU and not just one particular problem like the clutch position. From the sudden onset of the problem, I suspect something is totally gone: sensor, magnet or connection. First thing I would check would be the integrity of the sensor and its wiring. Sorry, this is long on theory and short on practicality, but I hope it helps.

Of course, part of this game is spending huge sums of money in keeping our prides-and-joy going.

Tom
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Was this issue ever resolved? The same thing happened to me, car worked fine but suddenly one morning when starting up i got this code, and code p1710, car shuts down when trying to engage gear when car is running. All this only happens intermittently

I have changed the clutch position sensor and the connector to it but problem persists.

I didn´t change the magnet as the old one was not cracked or out of position. Could this really be the problem?

When i monitor the clutch position with the diagnostic computer, it sometimes becomes unstable, starts drifting, jumping back and forth. This happens with ignition on, engine off so the clutch is not moving.

If it is the TCU, have anyone managed to repair a broken one? The TCU feeds the primary coil in the clutch position sensor (LVDT-sensor) with alternating current so maybe there is a capacitor whitin that circuit that is broken or soemthing else that is possible to repair.