Symptom:
*TRANSMISSION SHIFTS EARLY WITH NO DTC’S
POSSIBLE CAUSES
VEHICLE BUS PROBLEMS
CHECK FOR INTERMITTENT WIRING & CONNECTORS
COLD TRANSMISSION
TEST
ACTION
APPLICABILITY
1
Using the DRBIII
t, check all other Modules for signs of a PCI bus problem such as
bus related DTC’s and/or communication problems.
Check and diagnose all 1 trip failures as a hard code.
Although it takes two occurences of a missed TRD link message to set the DTC
P1793, one missed message will cause the transmission to short shift until the next
start up. If the vehicle has any indications of a bus problem, the bus must be repaired
first
Do any of the other modules show signs of a bus problem?
All
Yes
→ Refer to the Communication category and perform the appropri-
ate diagnostics.
No
→ Go To 2
2
The conditions necessary to set the DTC are not present at this time. Using the
schematics as a guide, inspect the wiring and connectors specific to this circuit.
Wiggle the wires while checking for shorts and open circuits.
Although it takes two occurences of a missed TRD link message to set the DTC
P1793, one missed message will cause the transmission to short shift until the next
start up. If the vehicle has any indications of a bus problem, the bus must be repaired
first
Were there any problems found?
All
Yes
→ Repair as necessary.
No
→ Go To 3
3
If the transmission shifts too early when the transmission is cold, this is a normal
condition. The software is designed to protect the transmission from high torque
and/or high RPM shifts during cold operation.
Did the problem occur when the transmission temperature was cold?
All
Yes
→ This is a normal condition. The software is designed to protect the
transmission from high torque and/or high RPM shifts during
cold operation.
No
→ Test Complete.
160
TRANSMISSION - NGC