DTC 312

EBD. Code 3-1-2

3-1-2 Transmission RPM signal incorrect

DTC information


Conditions for DTC






The transmission rpm signal is sent by the rpm sensor on the transmission. The transmission control module TCM uses the signal to work out the rpm on the input shaft after the torque converter. This signal is used to compare the transmission rpm with the car's road speed. The TCM uses this comparison in calculating gear-shift points. The rpm and road speed data are also utilized in modulating system pressure, lock-up function control and in torque-reduction. The end result is smooth shifting. If the TCM registers an unusually large variation in the signal voltage, DTC 3-1-2 is set.



Substitution value

Control Module GROUP I:
No substitution value

Control Module GROUP II:
The transmission control module (TCM) "Emergency mode II program is initiated.


Defect cause

- Loose contact in the wiring or cable splices
- Cable insulation damaged
- Malfunction in the rpm sensor.
- Interference from other Systems or accessories
- Contact resistance in connections.


Fault symptom

- Rough gear shifting due to maximum system pressure in the transmission (Emergency mode II)
- No Lock-up operation (Emergency mode II).
- Fault-tracing starts with EBD1.




EBD1

Other DTCs.






- Read off other DTCs

If DTC 3-1-1 is stored:
- Fault-tracing as per EBC. DTC 3-1-1 RPM signal absent. DTC 311

If DTC 3-1-1 is not stored:
- Checking wiring and connections EBD2.




EBD2

Checking wiring and connections






- Check that the rpm sensor is in position.
- Check the transmission connector and the TCM connector for loose connections as per FA5, and contact resistance and oxidation as per FA6. FA. Checking Wiring and Connections

- Check the cables between the rpm sensor and the TCM #A1 and #A2 for intermittent breaks as per FA2, intermittent short circuit to supply as per FA4, intermittent short circuit to ground as per FA3, intermittent short circuit between the cables. FA. Checking Wiring and Connections

Then continue with: Checking for interference EBD3.



EBD3

Checking for interference

- Check the rpm sensor wiring is not located too near sources of interference, such as electric motors, sparkplug leads, mobile telephone cables etc.

Then continue with: Checking the rpm sensor EBD4.



EBD4

Checking the rpm sensor

- Ignition ON.
- Clear DTCs
- Test drive the car as per Test Drive Form. Test Aide Drive Form






If the DTC is set again:
- Try a new rpm sensor as per YI-Y7