Description of operation, function chains: Diagnostics
ABS has extremely good diagnostics for its wheel sensors. This means that with a high degree of certainty the wheel speed signals will be present on the control module's four outputs if no diagnostic trouble codes have been generated in the system.
Neither the main instrument panel nor any of the other bus systems have speed signal diagnostics for the LH rear wheel. If the speedometer is working, however, it is certain that speed information is present on the bus and consequently available to all systems connected to the bus.
If the speedometer is not working, the speed reading obtained on any bus system is always 0, and there are no diagnostic trouble codes in ABS, then the fault is probably in the lead between ABS and MIU.
Trionic has diagnostics on the speed signal for the RH front wheel, but it may require longer driving without a speed signal for a DTC to be set.
A readout of the two speed signals used in the car can be obtained from Trionic using the diagnostic tool.
When TWICE, MIU or the Trionic control module is replaced, immobilization must be reprogrammed in TWICE. If this is not done, the engine cannot be started and DTC P1460 is set in Trionic.
If immobilization is not reprogrammed in TWICE, the following DTCs are set in TWICE: DTC B1780 with replacement of Trionic, DTC B1782 with replacement of MIU.
If the diagnostic trouble code is generated even though programming was carried out, fault diagnosis will have to be carried out on the immobilization function in TWICE.