DTC 311

EBC. Code 3-1-1

3-1-1 Transmission RPM signal absent

DTC information

Conditions for DTC







The transmission rpm signal comes from an 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 does not register the signal when the the car's road speed is over approx. 25 km/h (15 mph), the DTC 3-1-1 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
- Break in the signal (+) wiring or signal (-) wiring.
- Signal (+) wiring or signal (-) wiring short-circuited to ground or supply
- Short circuit between the signal (+) wiring and signal (-) wiring.
- Malfunction in the rpm sensor.
- 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 EBC1.



EBC1

Checking rpm signal






- Test drive the car

Check rpm sensor operation using Diagnostic Test Mode 5. Diagnostic Test Mode 5

If rpm sensor is operating:
- Intermittent fault, fault-tracing as per EBC8.

If the rpm sensor is not operating:
- Checking rpm sensor circuit EBC2.



EBC2

Checking rpm sensor circuit






- Ignition OFF
- Connect test box and check ground points as per GB1-GB2 GB. Connecting the Test Box

- TCM disconnected

Use an ohmmeter to measure between #1 (#A1) and #2 (#A2) on the test box.
The ohmmeter should read 300-600 Ohms.






If reading is OK:
- Checking the signal wiring EBC7.

If reading is incorrect:
- Checking the rpm sensor resistance EBC3.



EBC3

Checking rpm sensor resistance






- Ignition OFF
- Remove the air cleaner (ACL) housing to access the transmission connector
- Disconnect the transmission connector.
- TCM disconnected.

Connect an ohmmeter between the transmission connector terminals 16 and 17 (rpm sensor side).

The ohmmeter should read 300-600 Ohms.

If reading is OK
- Checking resistance in signal (+) wiring EBC3.

If reading is incorrect:
- Check the cables between the rpm sensor and transmission connector terminal 16 and 17 for break as per FA2 and short circuit between the cables. FA. Checking Wiring and Connections

If the wiring is OK: Try a new rpm sensor as per Y1-Y7.



EBC4

Checking resistance in signal (+) wiring






- Ignition OFF
- Disconnect transmission connector
- TCM disconnected.

Connect an ohmmeter between the transmission connector terminal 16 (TCM side) and #1 (#A1) on the test box.

The ohmmeter should read approx. 0 Ohms.






If reading is OK:
- Checking resistance in signal (-) wiring EBC5.

If reading is incorrect:
- Check the cable between the transmission connector terminal 16 and TCM #A1 for breaks in the circuit as per FA2. FA. Checking Wiring and Connections



EBC5

Checking resistance in signal (-) wiring






- Ignition OFF
- Disconnect transmission connector
- TCM disconnected.

Connect an ohmmeter between the transmission connector terminal 17 (TCM side) and #2 (#A2) on the test box.

The ohmmeter should read approx. 0 Ohms.






If reading is OK:
- Checking the signal wiring resistance EBC6.

If reading is incorrect:
- Check the cable between the transmission connector terminal 17 and TCM #A2 for breaks in the circuit as per FA2. FA. Checking Wiring and Connections




EBC6

Checking signal wiring resistance






- Ignition OFF
- Disconnect transmission connector
- TCM disconnected.

Use an ohmmeter to measure between #1 (#A1) and #2 (#A2) on the test box.
The ohmmeter should read infinite resistance.

If reading is OK:
- The DTC was set because of poor contact in the TCM and transmission connectors. Check and correct the connectors for contact resistance and oxidation as per FA6 FA. Checking Wiring and Connections

If reading is incorrect:
- Check the cable between the transmission connector terminal 16 and TCM #A1 for short circuit to cable between the transmission connector terminal 17 and TCM #A2.



EBC7

Checking the signal wiring






- Ignition OFF
- Test box connected
- Connect TCM
- Ignition ON.

Use a voltmeter to measure between #1 (#A1) and #20 (#A20) on the test box.
The voltmeter should read approx. 2.5 V.

If reading is OK
- The DTC was set because of poor contact in the TCM connector. Check and correct the transmission and TCM connectors for contact resistance and oxidation as per FA6 FA. Checking Wiring and Connections

If the voltmeter reads less than approx. 2.5 V:
- Check the cables between the rpm sensor and TCM #A1 and #A2 for short circuit to ground as per FA3. FA. Checking Wiring and Connections

If the voltmeter reads more than approx. 2.5V:
- Check cables between rpm sensor and TCM #A1 and #A2 for short circuit to supply as per FA4. FA. Checking Wiring and Connections



EBC8

Intermittent fault

Checking wiring and connections







- 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 and intermittent short circuit to supply as per FA4 and intermittent short circuit to ground as per FA3. FA. Checking Wiring and Connections

- Check the cables between the rpm sensor and TCM #A1 and #A2 for intermittent short circuit between the cables.