Serial Communications

A serial communications system allows signals to be sent back and forth between the vehicle ECU's and JDS, via the vehicle wiring harness. Three ECU's on the 1990 MY Sedan Range have serial communication capability, with each having a different level of fault retention as follows:

Instrument Pack- (Pod 7 is connected at LS131)
^ Does not store any fault information regarding instrument pack faults.

Engine Management- (Pod 7 is connected to LI57)
^ Stores permanent and intermittent engine management faults, but cannot identify one from the other.
^ Information on the faulty system(s) is available by reading the EMS trace fault table (fault table reading is included in this bulletin).

Electronic Transmission- (Pod 7 is connected to LI57).
^ Stores permanent and intermittent faults and identifies one from the other.
^ Five different faults can be stored in the ECU's memory.