Scania Truck Engine DTCs

Access to fault codes through the coordinator

A diagnostic scanner or a diagnostic lamp located on the dashboard can be used to display fault codes.

Read fault codes:

Turn on the onboard power supply. Press the diagnostic tool, the switch and hold it down for 2 seconds. When reading fault codes, it should be borne in mind that long flashes are diagnosed. the lamps correspond to the tens digit, and short flashes to the discharge unit in the digital trouble code.

In the example shown in the figure, fault code 21 is issued as follows: long flash - long flash. - short flash. If there are no fault codes, the diagnostic lamp will turn on once and will continue to light for 4 seconds. To read the next fault code, press the diagnostic tool, switch again.

Erasing trouble codes:

To erase all fault codes, do the following.

1. Turn off the power to the vehicle electrical system (line 15).

2. Press and hold the diagnostic tool, the switch is pressed.

3. Turn on the power to the on-board network (line 15) while continuing to hold the diagnostic tool, the switch in the down position.

Store fault codes in control unit memory

The memory of the EOS control unit is sufficient to store 10 fault codes.

The fault codes of the machine, are arranged by priority. When the memory is filled with fault codes, the fault codes of the highest priority are saved, the lowest - are erased. Fault codes are stored in 2 different memory segments of the control unit. When the codes are erased by the diagnostic switch, all fault codes are cleared, which are indicated by the flashing of the alarm lamp. However, the fault codes remain in another memory segment, access to which is possible only with the help of a diagnostic scanner. The diagnostic scanner allows you to find out how many times each of the faults has been fixed.

This information may be useful, for example, if there is an unreliable contact in the connector. The diagnostic scanner simultaneously erases fault codes from both memory segments of the control unit. If a

the memory, which can be entered using a personal computer (PC), is filled, new fault codes with a lower priority cannot enter the memory even if the old codes are erased using the diagnostic switch.

When the eleventh low priority code appears, the indicator lamp will light. The indicator lamp is lit and does not indicate a malfunction, but the memory remains empty. When re-memorizing the malfunction code in the computer's memory (PC), a flash code is formed and the indicator lamp lights up.

Limitations of diagnostic capabilities

Despite the perfect software, there may be such faults that the control unit will not be able to distinguish from the normal functioning of the system. In such cases, fault codes are not set. Fault codes can be set if you disconnect the wire when the on-board power is on.

This is quite a typical case.

The control unit interprets the disconnection of the wire as a fault. In case of violation of electr. connections may malfunction spontaneously.

However, this fault code will be stored in the memory of the control unit until it is erased. Even if the malfunction has disappeared, this allows one to later find out in which circuit there was a malfunction and to eliminate the cause of this malfunction.

Faults, the occurrence of which does not establish codes: In the absence of information from the engine control unit regarding the coolant temperature, the pointer indicator is set to

maximum temperature. In this case, the fault code in the block-coordinator is absent. In the absence of information from the engine control unit regarding the oil pressure, the dial gauge is set to zero (complete absence of oil pressure). In this case, the fault code

STI in the block-coordinator is missing.

List of fault codes

DTC 11

Malfunction:

Forbidden signal from the potentiometer of the gas pedal position sensor.

Symptoms / causes of failure:

The signal voltage on the plug 54 is too low or too high.

Notes: The potentiometer signal voltage is less than 0.2 V (approximately) or greater than 4.0 V (approximately). Since the supply voltage and electr. the resistance of the potentiometer of the gas pedal sensor may vary slightly at different a / m, then the voltage values given are

only indicative.

Elimination:

Check the potentiometer of the gas pedal sensor, electr. connectors and wiring.

DTC 12

Malfunction:

Prohibited discrepancy between the potentiometer signal and the state of the gas pedal limit switch.

Symptoms / causes of failure:

The signal voltage on plug 54 is too low - provided that plug 30 is connected to “ground.” Or vice versa, the signal voltage on plug 54 is too high, provided that there is no connection to ground plug 30. The potentiometer signal voltage was below 0.49 V, while the gas pedal limit switch was in the closed state. Or vice versa, the potentiometer signal voltage exceeded 0.90 V, while the pedal limit switch

gas was in the open state.

Notes: The signals of the limit switch and the gas pedal potentiometer must match. The signal of the potentiometer cannot indicate that the accelerator pedal is pressed, while the limit switch is in the open state, which corresponds to the idling of the engine.

Elimination:

Check potentiometer and throttle limit switch. Check electr. connectors and wiring.

DTC 13

Malfunction:

Prohibited signal from the cruise control switch box.

Symptoms / causes of failure:

The voltage between plugs 29 and 48 is too low or too high. The fault may also be in the deviation of the signal voltage from the specified

the intervals corresponding to the inclusion of the following functions: ACC, RES, RET, ON and OFF.

Notes: Until the malfunction is eliminated, the cruise control system and the engine idling frequency adjustment will not function. The control unit interprets the signal voltage as follows: 0.7-0.9 V: ON + AGC, (14.4-18.3% of the supply voltage); 1.6-1.7 V:

ON + RES, (31.2-35.1% of the supply voltage); 2.5-2.7 V: ON + RET, (49.6-53.5% of the supply voltage): 3.3-3.5 V: ON, (66.4-70.3% of the supply voltage ); 3.7-4.3 V: OFF,

(74.2-85.9% of the supply voltage). The above voltage signal ranges correspond to the supply voltage of 5 V. It should be noted that the supply voltage at different a / m may differ. The fault code is set if the signal voltage goes beyond the specified ranges.

Elimination:

Check the cruise control breaker box, electr. connectors and wiring.

DTC 14

Malfunction:

Lack of communication with the engine control unit.

Symptoms / causes of failure:

The communication between the engine control unit and the coordinator unit has been broken.

Notes: The engine control module malfunction indicator lights up. Reading engine trouble codes is not possible.

Elimination:

Check electr. connectors and wiring.

DTC 17

Malfunction:

Open or short circuit between the co-ordinator and the tachograph.

Symptoms / causes of failure:

There is no input signal on plug 41; or the signal voltage is too low or too high. A fault code can only be set if

a / m still

Notes: The block coordinator checks the operability of the communication line with the tachograph only on a stationary car. If the check indicates a communication failure, then a fault code is set. It is allowed to connect to the output D3 of the tachograph only devices intended to limit the maximum speed of the vehicle.

Elimination:

Check the operation of the tachograph. If the tachograph is working normally, then you should check the wire between the tachograph and the coordinator unit.

DTC 18

Malfunction:

The contradiction between the signals received from the limit switches (first and 2nd) brake. the pedals.

The signal of one limit switch indicates that the brake pedal is fully released, while the signal of the other limit switch corresponds to the depressed brake. the pedals.

Symptoms / causes of failure:

Both plugs 52 and 53 are simultaneously connected to the “ground” or none of them is connected to the “ground”. Both limit switches Torm. the pedals were simultaneously in the closed or open state for more than 5 minutes.

Notes: Until the malfunction is eliminated, the cruise control system and the engine idling frequency adjustment will not function.

Elimination:

Check limit switches, electr. connectors and wiring.

DTC 19

Malfunction:

A short circuit of the communication line with the engine control unit, through which the output R / L / M signal is transmitted, which regulates the amount of fuel injected into the engine.

Symptoms / causes of failure:

Output signal line shorted to power wire. A fault code is set if the fault has been present for more than 10 seconds.

Notes: If this DTC is set, other control units may also set the corresponding DTC.

Elimination:

Check electr. connectors and wiring.

DTC 21

Malfunction:

Short circuit of the transmission line signal to the pointer coolant temperature indicator.

Symptoms / causes of failure:

Output signal line shorted to power wire. A fault code is set if the fault has been present for more than 10 seconds.

Notes: In the event of this fault, the arrow indicator will indicate a lower temperature.

Elimination:

Check dashboard, electr. connectors and wiring.

DTC 22

Malfunction:

Short circuit of a signal transmission line to an arrow indicator of pressure of oil.

Symptoms / causes of failure:

Output signal line shorted to power wire. A fault code is set if the fault has been present for more than 10 seconds.

Notes: In the event of this fault, the arrow indicator will indicate a higher pressure.

Elimination:

Check dashboard, electr. connectors and wiring.

DTC 23

Malfunction:

Short circuit of the signal transmission line to the oil pressure drop alarm.

Symptoms / causes of failure:

Output signal line shorted to power wire. A fault code is set if the fault has been present for more than 10 seconds.

Notes: In the event of this fault, the oil pressure drop alarm will not turn on.

Elimination:

Check dashboard, electr. connectors and wiring.

DTC 24

Malfunction:

Short circuit plug 2 connector block coordinator.

Symptoms / causes of failure:

Short circuit of the transmission line output signal to ground, the fault code is set if the fault is present for more than 10 seconds.

Notes: In the event of this fault, the EOC malfunction indicator will not turn on, since it is connected to this output of the coordinator unit.

Elimination:

Check electr. connectors and wiring

DTC 25

Malfunction:

Discrepancy of the coordinator unit and the engine control unit by the method of data exchange.

Symptoms / causes of failure:

The coordinator unit cannot supply the engine control unit with the information it requests.

Notes: The DTC can be set, for example, after replacing one of the units with a new product that is supplied in spare parts. The coordinator unit can adapt to older versions of the engine control unit, but not to new ones. The engine control unit in the new version can request such information that the block coordinator does not have.

Elimination:

Check that the version of the installed engine control unit matches the version of the unit being replaced.