Symptom:
IC/ATC CAN MESSAGE MISSING
POSSIBLE CAUSES
CAN BUS CIRCUIT DTC PRESENT
AUTOMATIC TEMP CONTROL DTCS PRESENT
INSTRUMENT CLUSTER DTCS PRESENT
OPEN CAN BUS CIRCUITS AT INSTRUMENT CLUSTER
OPEN CAN BUS CIRCUITS AUTOMATIC TEMP CONTROL
AUTOMATIC TEMP CONTROL
INSTRUMENT CLUSTER
TEST ACTION APPLICABILITY
1NOTE: 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 DRBIIIt, read the engine DTCs. Check and repair all engine DTCs prior to
performing transmission symptom diagnostics.
With the DRBIIIt, 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 Ignition on, engine not running.
With the DRBIIIt, read Transmission DTCs.
NOTE: If the DTC, CAN BUS CIRCUIT, is present, perform diagnostics on
that symptom first.
Is the DTC, CAN BUS CIRCUIT, present?All
Ye s!Refer to the Transmission category and perform the appropriate
symptom.
No!Go To 3
3NOTE: NOTE: If vehicle is equipped with Air Conditioning diagnose the ATC
system first.
Is the vehicle equipped with air conditioning?All
Ye s!Go To 4
No!Go To 6
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TRANSMISSION - NAG1
TEST ACTION APPLICABILITY
4 Ignition on, engine not running.
With the DRBIIIt, read Automatic Temp Control DTCs.
Are there any ATC DTCs present?All
Ye s!Refer to the Heating and A/C category and perform the appropri-
ate symptom.
No!Go To 5
5 Turn the ignition off to the lock position.
Disconnect the ATC harness connector.
Measure the resistance between the CAN Bus (+) circuit and the CAN Bus (-) circuit
in the ATC harness connector.
Is the resistance 60 ohms, 3.0 ohms?All
Ye s!Replace the Automatic Temp Control per the service information.
No!Repair the CAN C Bus (+) or the CAN C Bus (-) circuit for an open.
6NOTE: If vehicle is equipped with Air Conditioning diagnose the ATC
system first.
Ignition on, engine not running.
With the DRBIIIt, read Instrument Cluster or Automatic Temp Control DTCs.
Are there any Instrument Cluster DTCs present?All
Ye s!Refer to the INSTRUMENT CLUSTER category and perform the
appropriate symptom.
No!Go To 7
7 Turn the ignition off to the lock position.
Disconnect the Instrument Cluster C1 harness connector.
Measure the resistance between the CAN Bus (+) circuit and the CAN Bus (-) circuit
in the Instrument Cluster harness connector.
Is the resistance 60 ohms, 3.0 ohms?All
Ye s!Replace the Instrument Cluster per the service information.
No!Repair the CAN C Bus (+) or the CAN C Bus (-) circuit for an open.
73
TRANSMISSION - NAG1
IC/ATC CAN MESSAGE MISSING ÐContinued
