TEST
ACTION
APPLICABILITY
1
NOTE: Low fluid level can be the cause of many transmission problems. If
the fluid level is low locate and repair the leak then check and adjust the
fluid level per the service information.
NOTE: Always perform diagnostics with a fully charged battery to avoid
false symptoms.
With the DRBIII
t, read the engine DTCs. Check and repair all engine DTCs prior to
performing transmission symptom diagnostics.
With the DRBIII
t, read and record all Transmission DTCs.
NOTE: Check connectors - Clean/repair as necessary. Poor pin to terminal
connections can set DTCs.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
Repair as necessary.
Most DTCs set on start up but some must be set by driving the vehicle such that all
diagnostic monitors have run.
Note: Verify flash level of transmission controller. Some problems are
corrected by software upgrades to the transmission controller.
NOTE: Check for any Technical Service Bulletins that may apply.
Perform this procedure prior to Symptom diagnosis.
All
Continue
Go To
2
2
With the DRBIII
t, read the active and stored DTCs for all modules that use CAN Bus
communication.
NOTE: Due to capabilities of certain controllers that use the CAN Bus, not
all modules report CAN Bus DTCs.
NOTE: If a total CAN Bus failure transpires, there will be multiple CAN Bus
DTCs present in many modules. If the other modules are reporting Trans-
mission CAN Bus messages ONLY, answer No for the following question.
Are other modules reporting active or stored CAN Bus communication DTCs?
All
Yes
→ Go To 3
No
→ Go To 12
3
Turn the ignition off to the lock position.
Disconnect the negative battery cable.
While back probing, measure the resistance between the CAN C Bus (+) and the CAN
C Bus (-) in the selected control module harness connector.
NOTE: Termination of the CAN Bus is located in the ECM and SKREEM.
Both modules use a 120.0 ohm resistor for termination of the CAN Bus. A
properly terminated CAN Bus will read 60.0 ohms ± 5.0 ohms.
Pick the one that best describes your readings:
All
60.0 ohms ± 5.0 ohms.
Go To
4
120.0 ohms ± 5.0 ohms.
Go To
10
Less than 60.0 ohms
Go To
8
49
TRANSMISSION - NAG1
CAN BUS CIRCUIT —
Continued