Controller Area Network (CAN) Bus (Automatic gearbox - Jatco)
- Make
- Land Rover
- Model
- Freelander System Description and Operation (UK)
- Section
- Description and operation › Controller Area Network (CAN) Bus
| P Code | Component | Description |
|---|---|---|
| P0753 | Shift solenoid A | Open circuit or short circuit to earth or battery |
| P0758 | Shift solenoid B | Short circuit to earth or battery |
| P0763 | Shift solenoid C | Short circuit to earth or battery |
| P0790 | Mode switch input | Multiple signal |
| P1562 | Power supply voltage | Out of range |
| P1605 | EAT ECU EEPROM | Error flag set |
| P1715 | Intermediate speed sensor | No signal |
| P1748 | 2-4 brake duty solenoid | Open circuit or short circuit to earth or battery |
| P1785 | Low clutch timing solenoid | Short circuit to earth or battery |
| P1786 | Reduction timing solenoid | Short circuit to earth or battery |
| P1787 | 2-4 brake timing solenoid | Open circuit or short circuit to earth or battery |
| P1815 | Steptronic (manual) +/- switch input signals | Multiple signals/No signal |
| P1825 | Shift interlock ECU | Shift interlock failure |
| P1840 | CAN Bus | CAN Bus malfunction |
| P1841 | CAN Bus monitoring | CAN Bus off |
| P1842 | CAN level monitoring | Incompatible |
| P1843 | CAN timeout monitoring | CAN Bus missing nodes detected |
| P1844 | Engine RPM (speed signal) Engine temperature signal Torque reduction signal Throttle angle signal Virtual throttle angle | Error flag set Error flag set Torque reduction volume not achieved Error flag set Error flag set |
Controller Area Network (CAN) Bus
The CAN bus is a high speed broadcast network between the ECM, instrument pack, ABS ECU and the EAT ECU allowing fast exchange of data between the ECU's every few microseconds.
The bus comprises two wires which are identified as CAN low (L) and CAN high (H). The wires are twisted together to minimise the electromagnetic interference (noise) produced by the CAN messages.
To prevent message errors from electrical reflections, 120Ω resistors are incorporated into the CAN wire terminals of the ECM, instrument pack, ABS ECU and the EAT ECU.
CAN messages consist of a signal which is simultaneously transmitted, in opposite phase, on both wires. CAN L switches between 2.5 and 1.5 volts, while CAN H switches between 2.5 and 3.5 volts. This causes a potential difference between the two lines to switch between 0 volt (logic 1) and 2 volts (logic 0) to produce the digital signal message.
In the event of a CAN bus failure any of the following symptoms may be observed: l Transmission defaults to 4th gear l Torque converter lock-up control is disabled l Transmission of torque reduction message to the ECM is inhibited.
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