19 BUS Communication With Engine Module

Part 1 Of 2:

Part 2 Of 2:

NOTES:
- PCM BUS communication with body module 1998 and later. Programmable communications interface is a single wire communications system.

- CCD BUS communication with engine module 1997 and prior. Chrysler Collision Detection is a two wire communications system.

THEORY OF OPERATION:
The Transmission control Module requires communications with one of the two multiplexed BUS options: CCD or PCI BUS (see above). The controller continuously monitors the BUS activity and receives the messages it needs. This code does not cause the transmission to go into limp in mode. However, it results in delayed 3-4 shift, early 4-3 shift and no torque converter clutch operations for a few minutes after the engine is started.

NOTE: If the transmission controller fails to operate, check the battery, ignition and ground wires to the controller for a open or short. Before replacing the controller. The MIL light will be illuminated by the engine controller due to a "no bus communications" response from the transmission controller.

LIMP-IN:
NO

WHEN MONITORED/SET CONDITIONS:
Communications tested every 7 milliseconds. Engine rpm must not be equal to zero. This code sets in approximately 10 seconds if no CCD/PCI messages are received for 10 seconds. The following conditions must be met for a successful OBDII trip:
- The engine must be run for more than 2 minutes
- The input speed (Turbine Speed) must be greater than 600 RPM or the output speed must be greater than 400 RPM
- If the transmission is either cool or warm, all forward gears must be applied for 3.5 seconds each and the transmission must be in park or neutral for 3.5 seconds
- If the transmission is hot, all forward gears must be applied for 1.5 seconds each and the transmission must be in park or neutral for 1.5 seconds
- No MIL lamp trouble codes have occurred or reoccurred

TRANSMISSION EFFECTS:
- Delayed upshifts and early downshifts
- No torque converter clutch operation


POSSIBLE CAUSES:

PCI BUS 1998 And Later
- A no response from the TCM will cause the PRNDL indicator to light all positions
- A total PCI BUS failure will cause a (NO BUS) message to appear in the odometer indicator
- Open or short circuits between transmission control module and the Powertrain Control Module
- Body Control Module PCI circuit problem
- Powertrain Control Module PCI circuit problem
- Transmission Control Module PCI circuit problem
- The PCI BUS does not require biasing (each controller handles it's own biasing)

CCD BUS 1997 And Prior
- Open or short circuits between Transmission Control Module and the Powertrain Control Module
- Powertrain Control Module CCD circuit problem
- Transmission Control Module CCD circuit problem
- CCD BUS biasing problem (BUS has to be properly biased by one the vehicle's controllers)