Diagnostics communication
| Diagnostics communication |
The systems that are not connected to the bus, ABS, AHL (Automatic Headlamp Levelling) and the additional heater for diesel (DAH) are connected to pin 8 of the data link connector with their own communication cable.
On cars with Traction Control and ESP, the TC/ABS and ESP control modules are connected to the bus, but diagnostics communication is done via the K-lead.
The diagnostic tool communicates digitally and serially with the selected system. Digitally means that the voltage difference between the lead and ground only has two values. In this case, approx. 0 V and B+. The information is coded so that different combinations of 0 V and B+ pulses mean different things, such as whether ABS or AHL should be called.
Serial means that the information is sent in “packets” which are transmitted one after the other in rapid succession.
Diagnostics
If none of the systems can be contacted, the fault may be either in the car or the diagnostic tool. If the diagnostic tool can contact one of the systems concerned in another car, then the fault is in the car.Check first that the control module is awake. The ABS, TC/ABS, ESP and AHL warning lamps are tested by the control module directly after ignition is switched on. If the control module is awake, the fault is probably localised to the lead between the data link connector and the control module.
If Trionic receives no communication from TC/ABS for 3 seconds during operation, DTC P1625 is set.
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