DTC 231

EAX. Code 2-3-1

2-3-1 Irregular throttle position (TP) signal

DTC information

Conditions for DTC







The throttle position TP signal is passed from the TP sensor at the throttle body by the transmission control module TCM. The signal tells the TCM how far the throttle damper has opened. The TCM uses the signal in its control functions, among them controlling gear-shifting and the system pressure. The signal normally varies between approx. 0.5 and approx. 4.2 V. Opening the throttle damper increases the signal voltage. If the TCM registers an unusually large variation in the signal voltage , DTC 2-3-1 is set.


Substitution value

No substitution value

Defect cause

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


Fault symptom

- Rough gear shifting due to maximum system pressure in the transmission
- No Lock-Up operational.
- Fault-tracing starts with EAX1.



EAX1

Other DTCs.






- Read off other DTCs in the engine control module (ECM MFI Fenix 5.2, LH 3.2 or Motronic 4.3).


If DTC 2-4-3 for Fenix 5.2, 4-1-1 for LH 3.2 or 4-1-1 for Motronic 4.3 ECM has been stored:
- Fault-tracing procedures as indicated by the DTC for the ECM.






If none of the above DTCs have been stored:
- Checking voltage drop over signal ground and power EAX2.



EAX2

Checking voltage drop over signal ground and power ground






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

- TCM connected
- Ignition ON.
- Turn on as many power consuming items as possible.

Use a voltmeter to measure between #20 (#A20) and #29 (#A29) on the test box.
The voltmeter should read less than 0.6V.






If reading is OK:
- Checking voltage drop over signal ground EAX3

If reading is incorrect:
- Check ground points 31/32 and 31/33, the cables between the ground points and the TCM #A20 and #A29, and the TCM connector for a break in the circuit as per FA2 and contact resistance and oxidation as per FA6. FA. Checking Wiring and Connections

Then continue with: Checking voltage drop over signal ground EAX3



EAX3

Checking voltage drop over signal ground






- Ignition OFF
- Test box connected
- Connect a test box to the engine control module ECM (MFI Fenix 5.2, LH 3.2, or Motronic 4.3).
- Control modules connected
- Ignition ON.
- Turn on as many power consuming items as possible.

Use a voltmeter to measure between transmission test box #20 (#A20) and the ECM test box:

- Fenix 5.2 MFI control module: #42 (#A42) signal ground, control module
- LH 3.2 MFI control module: #20 (#A20) signal ground, control module
- Motronic 4.3 MFI control module: #42 (#A42) signal ground, control module







The voltmeter should read less than 0.1 V.

If reading is OK:
- Checking the throttle position TP sensor EAX4.

If reading is incorrect:
- Check ground point 31/33, wiring between the ground point and the TCM and ECM modules for contact resistance and oxidation as per FA6. FA. Checking Wiring and Connections

Then continue with: Checking the throttle position TP sensor EAX4.



EAX4

Checking the throttle position TP sensor






- Ignition ON.
- Control modules connected

Use a voltmeter to measure between #50 (#B20) and #20 (#A20) on the transmission test box.

- Depress the accelerator pedal AP slowly several times and take a reading.

The voltmeter should read approx. 0.5 V for closed throttle position CTP and approx. 4.2 V at wide open throttle WOT. The voltage should increase as the AP is pressed down and not show any indication of open circuits, breaks etc.

If the signal is OK:
- Checking interference EAX5.

If the signal shows wide variations (indicating open circuit, break etc):
- Repeat test with new TP sensor


EAX5

Checking interference

- Ignition OFF

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

- Check that the cable between the TCM #B20 and the ECM #B20 for Fenix 5.2, LH 3.2 or Motronic 4.3 is not located near sources of interference, such as electric motors, sparkplug leads, mobile telephone cables etc.

- On cars with engine management systems type LH 3.2/EZ129K, also check the cable between ECM LH 3.2 #B20 and EZ129K #B20 for possible sources of interference.

Correct faults if any.

Then continue with: Intermittent fault EAX6.



EAX6

Intermittent fault Checking wiring and connections






- Check the cable between the TCM #B20 and the ECM #B20 for Fenix 5.2, LH 3.2 and Motronic 4.3 for intermittent break as per FA2, intermittent short circuit to ground as per FA3 and intermittent short circuit to supply as per FA4. FA. Checking Wiring and Connections

- On cars with engine control modules ECM type LH 3.2/EZ129k, also check the cable between ECM LH 3.2 #B20 and EZ129K #B20 for intermittent short circuits to ground as per FA3 and intermittent short circuits to supply as per FA4. FA. Checking Wiring and Connections

- Check the TP sensor circuit for the ECM installed:

Fenix 5.2 DTC 2-4-3 TP signal, intermittent malfunction
LH 3.2 DTC 4-1-1 TP sensor signal, intermittent malfunction, signal too low
LH 3.2 DTC 4-1-1 TP sensor signal, intermittent malfunction, signal too high
Motronic 4.3 DTC 4-1-1 TP sensor signal, intermittent malfunction, signal too low
Motronic 4.3 DTC 4-1-1 TP sensor signal, intermittent malfunction, signal too high