19 Bus Communicat on With Engine Module

WHEN MONITORED:
Every 0.007 second.

SET CONDITIONS:
1) Engine speed does not equal zero (engine cranking or running).

2) No CCD messages received for 10 seconds.

SET TIME:
If the above conditions are met, the code will set in approximately 10 seconds.

EFFECT:
1) Transmission does NOT enter limp-in, when this code is set.

2) Delayed 3/4 shift or early 4/3 shift for few minutes after engine is started.
OR
No lock-up operations for few minutes after the engine is started.

THEORY OF OPERATION:
EATX communicates with the engine controller over the CCD bus. Engine rpm, engine and ambient temperature are among the information received by EATX. The controller continuously monitors the bus activity and receives the messages it needs.

PROBABLE CAUSES:
Open serial bus (+) circuit or serial bus (-) circuits between EATX and engine controller.

Shorted serial bus (+) or serial bus (-) circuit. CCD bus biasing problem (bus has to be properly biased by one of the vehicle's controllers).

Engine controller CCD problem circuit.

EATX or body controller CCD circuit problem.