
Symptom:
SYSTEM OVERVOLTAGE
When Monitored and Set Condition:
SYSTEM OVERVOLTAGE
When Monitored: Always monitored with system active at each ignition cycle
Set Condition: Ignition voltage above 16.9 volts with the engine and transmission input
speed sensors above 2000 rpm for 60 seconds
POSSIBLE CAUSES
VEHICLE JUMP STARTED IMPROPERLY
ENGINE CHARGING SYSTEM DTC'S PRESENT
TRANSMISSION RELAY OUTPUT HIGH AT TCM
TCM - SYSTEM OVERVOLTAGE
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 Determine is the vehicle was jump started improperly.
NOTE: If the battery was jump started with the batteries in series, the
System Overvoltage DTC will be set.
Was the vehicle jump started improperly?All
Ye s!Erase the DTC , if the vehicle was jump started improperly.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 3
107
TRANSMISSION - NAG1

Symptom:
SYSTEM UNDERVOLTAGE
When Monitored and Set Condition:
SYSTEM UNDERVOLTAGE
When Monitored: Always monitored with system active at each ignition cycle.
Set Condition: Ignition voltage falls below 8.5 volts with the engine rpm greater than
2000 rpm for 60 seconds.
POSSIBLE CAUSES
ENGINE CHARGING SYSTEM DTC'S PRESENT
TRANSMISSION RELAY OUTPUT LO AT TCM
TCM - SYSTEM UNDER VOLTAGE
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 With the DRBIIIt, read Engine DTC's.
Are there any Engine Charging System DTC's present?All
Ye s!Refer to the Charging category and perform the appropriate
symptom.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 3
109
TRANSMISSION - NAG1

Symptom:
TCC OVER TEMP
When Monitored and Set Condition:
TCC OVER TEMP
When Monitored: Solenoid supply active. No Input Speed Sensor N2 - N3, CAN C Bus,
PCM/ECM, CAN Engine, CAN Engine Speed DTCs present. Torque Converter Clutch in
slip mode.
Set Condition: Friction loss factor reaches threshold.
POSSIBLE CAUSES
INTERNAL TRANSMISSION
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 This DTC is an informational DTC.
Check for any TSBs or Controller updates that may apply.
This is usually a sign of TCC failure or internal transmission problems.
Check the Engine and Transmission Cooling Systems for proper operation.
View repair.All
Repair
Repair internal Transmission as necessary. Refer to the Service
Information for proper repair procedure.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
111
TRANSMISSION - NAG1

Symptom:
TCC SOLENOID CIRCUIT
When Monitored and Set Condition:
TCC SOLENOID CIRCUIT
When Monitored: Always monitored with system active at each ignition cycle.
Set Condition: If the TCM detects a short to ground or battery on the solenoid control
circuit, shorted solenoid, open solenoid, or an open or shorted solenoid control circuit driver
in the TCM.
POSSIBLE CAUSES
INTERMITTENT WIRING AND CONNECTORS
TCC SOLENOID CONTROL CIRCUIT OPEN
TCC SOLENOID CONTROL CIRCUIT SHORT TO GROUND
TCC SOLENOID CONTROL CIRCUIT SHORT TO OTHER CIRCUITS
TCC SOLENOID
TCM - TCC SOLENOID CIRCUIT
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
11 2
TRANSMISSION - NAG1

Symptom:
TCC STUCK ON
When Monitored and Set Condition:
TCC STUCK ON
When Monitored: No Input Speed Sensor N2 - N3, CAN C Bus, PCM/ECM, CAN Engine,
No CAN Engine Torque and/or Shift in progress DTCs present. Must be in a valid forward
gear.
Set Condition: Engine RPM - Turbine Speed is greater than 30 RPM when the Engine
torque is less than 100 NM for 1.0 second
POSSIBLE CAUSES
TCC SOLENOID CONTROL CIRCUIT SHORT TO GROUND
TCC SOLENOID CONTROL CIRCUIT SHORT TO OTHER CIRCUITS
INTERNAL TRANSMISSION
TCM - TCC STUCK ON
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
11 5
TRANSMISSION - NAG1

Symptom:
TRANS TEMP SENSOR - P/N SWITCH CIRCUIT
When Monitored and Set Condition:
TRANS TEMP SENSOR - P/N SWITCH CIRCUIT
When Monitored: Always monitored with system active at each ignition cycle.
Set Condition: Temp sensor is open while in forward gears (1-5), temp sensor, open Trans
temp circuit, P/N Switch.
POSSIBLE CAUSES
SHIFTER ADJUSTMENT
SENSOR GROUND CIRCUIT OPEN
TEMP SENSOR - P/N SWITCH CIRCUIT OPEN
TEMP SENSOR - P/N SWITCH CIRCUIT SHORT TO GROUND
SENSOR GROUND CIRCUIT SHORT TO OTHER CIRCUITS
TEMP SENSOR- P/N SWITCH CIRCUIT SHORT TO OTHER CIRCUITS
TEMP SENSOR - P/N SWITCH
TCM - TEMP SENSOR - P/N SWITCH
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
11 7
TRANSMISSION - NAG1

Symptom:
TRANS TEMP SENSOR ERRATIC
When Monitored and Set Condition:
TRANS TEMP SENSOR ERRATIC
When Monitored: When transmission temperature is below 170É C (338É F)
Set Condition: When there is a 10É C (18É F) variation between each transmission
temperature sensor read. If the DTC is reset (after an ignition cycle), the DTC will be set
to Stored (Intermittent) status.
POSSIBLE CAUSES
TRANSMISSION TEMP SENSOR WIRING
TCM - TRANS TEMP SENSOR ERRATIC
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, monitor the Transmission Temperature.
With the brakes firmly applied, place the gear selector in Drive.
While monitoring the DRBIIIt, wiggle the wires and connectors from the TCM to the
Transmission Solenoid Assembly.
Did the Transmission Temperature fluctuate while wiggling the wires?All
Ye s!Repair the wiring and/or connectors as necessary.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 3
120
TRANSMISSION - NAG1

Symptom:
TRANS TEMP SENSOR SHORTED
When Monitored and Set Condition:
TRANS TEMP SENSOR SHORTED
When Monitored: Always monitored with system active
Set Condition: Temperature sensor input below a threshold, failed temperature sensor,
short to ground, TCM
POSSIBLE CAUSES
TEMP SENSOR - P/N SWITCH CIRCUIT SHORT TO GROUND
TEMP SENSOR - P/N SWITCH CIRCUIT SHORT TO OTHER CIRCUITS
TCM - P/N SWITCH CIRCUIT
TRANSMISSION TEMPERATURE SENSOR
TCM - TRANS TEMP SENSOR SHORTED
TRANSMISSION TEMP SENSOR - P/N SWITCH
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 Attempt to start the vehicle in Park and Neutral.
Does the engine start in either position, Park or Neutral?All
Ye s!Go To 3
No!Go To 5
122
TRANSMISSION - NAG1