Information Bus: Description and Operation

Data Communications Link (DCL) Network:

The Data Communications Link (DCL) is a wiring system that allows the sharing of information between the Electronic Engine Control System (EEC- IV), the Message Center Control Assembly (MCCA) and the Cluster Control Assembly (CCA) located in the electronic instrument cluster panel by using a common link (DCL).

The EEC-IV system transmits the following information through the DCL to the CCA and MCCA:
1. Engine rpm.
2. Engine coolant temperature.
3. EEC-IV malfunction indication.
4. Fuel used.

The CCA transmits the following information through the DCL to the MCCA:
1. Fuel level.
2. Odometer.
3. Speed pulses.
4. Cluster display temperature.
5. Battery voltage warning.
6. Oil pressure warning.
7. English/Metric mode.
8. Vehicle in Accessory/Run (ACC/RUN) mode.
9. Engine temperature warning.
10. Charging system warning.

There are two EEC-IV, DCL strategies. One covers the 49-state application, the other covers California. The California strategy uses the EEC-IV system to transmit Malfunction Indicator Lamp (MIL) information to the MCCA. The MCCA uses MIL information to generate a CHECK ENGINE warning in the event of an engine sensor failure.

In the event of a DCL failure, an alternating message of CHECK ENGINE then CHECK DCL is displayed on the MCCA.