TEST ACTION APPLICABILITY
2 Ignition on, engine not running.
With the DRBIIIt, erase Transmission DTCs.
Raise the vehicle on the hoist.
Start the engine.
NOTE: This condition indicates a catastrophic transmission failure.
With the DRBIIItin Sensors, monitor the N2 and N3 Speed Sensors.
Firmly apply the brakes and place the gear selector in Drive (D).
Release the brakes and raise the engine RPM to allow the Transmission to upshift to
the 2-3 and 3-4 shift schedule.
CAUTION: BE SURE TO KEEP HANDS AND FEET CLEAR OF ROTATING
WHEELS.
Did either the N2 or N3 Speed Sensors display a RPM above 7700?All
Ye s!Go To 3
No!Go To 5
3 Remove the Transmission Oil Pan and inspect for debris or a plugged Transmission
Oil Filter.
Is there any debris, plugged Transmission Oil Filter, or signs of an Internal
Transmission problem?All
Ye s!Repair Internal Transmission as necessary. Pay particular atten-
tion to the Electrohydraulic Control unit. Refer to the Service
Information for proper repair procedures.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 4
4 If there are no possible causes remaining, view repair. All
Repair
Replace the Transmission Control Module.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
5 The conditions necessary to set this 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.
NOTE: Check for any Technical Service Bulletins that may apply.
Were there any problems found?All
Ye s!Repair as necessary
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Test Complete.
81
TRANSMISSION - NAG1
INPUT SENSOR OVERSPEED ÐContinued
Symptom:
INTERNAL CONTROLLER
When Monitored and Set Condition:
INTERNAL CONTROLLER
When Monitored: Always monitored with system active at each ignition cycle
Set Condition: This code is set whenever Transmission Control Module (TCM) senses an
internal error. If this Internal Controller DTC is set with any Solenoid DTC's repair the
Solenoid DTC's first, erase all DTC's, then verify the Internal Controller DTC sets before
replacing the TCM.
POSSIBLE CAUSES
TCM - INTERNAL ERROR
TEST ACTION APPLICABILITY
1 If there are no possible causes remaining, view repair. All
Repair
The Transmission Control Module is reporting internal errors and
must be replaced.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
82
TRANSMISSION - NAG1
Symptom:
MODULATING PRESSURE SOLENOID CIRCUIT
When Monitored and Set Condition:
MODULATING PRESSURE 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
MOD. PRESS SOLENOID CONTROL CIRCUIT OPEN
MOD. PRESS SOLENOID CONTROL CIRCUIT SHORT TO GROUND
MOD. PRESS SOLENOID CONTROL CIRCUIT SHORT TO OTHER CIRCUITS
MOD PRESS SOLENOID
TCM - MOD. PRESS 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
84
TRANSMISSION - NAG1
TEST ACTION APPLICABILITY
2 Ignition on, engine not running.
With the DRBIIIt, erase DTCs.
With the DRBIIIt, perform the Solenoid Test
With the DRBIIIt, read DTCs.
Did the DTC, Mod Press SOLENOID CIRCUIT, reset?All
Ye s!Go To 3
No!Go To 7
3 Turn the ignition off to the lock position.
Disconnect the Transmission Control Module C2 harness connector.
Disconnect the Transmission Solenoid Assembly harness connector
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the Mod. Press Solenoid Control circuit from the TCM C2
harness connector to the Transmission Solenoid Assembly harness connector.
Is the resistance above 5.0 ohms?All
Ye s!Repair the Mod. Press Solenoid Control circuit for an open.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 4
4 Turn the ignition off to the lock position.
Disconnect the Transmission Control Module C2 harness connector.
Disconnect the Transmission Solenoid Assembly harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance between ground and the Mod. Press Solenoid Control circuit.
Is the resistance below 5.0 ohms?All
Ye s!Repair the Mod. Press Solenoid Control circuit for a short to
ground.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 5
5 Turn the ignition off to the lock position.
Disconnect the Transmission Control Module C2 harness connector.
Disconnect the Transmission Solenoid Assembly harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the Mod Press Solenoid Control circuit to all other circuits
in the Transmission Solenoid Assembly harness connector.
Is the resistance below 5.0 ohms between any other circuit?All
Ye s!Repair the Mod. Press Solenoid Control circuit for a short to other
circuits.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 6
85
TRANSMISSION - NAG1
MODULATING PRESSURE SOLENOID CIRCUIT ÐContinued
TEST ACTION APPLICABILITY
6 Turn the ignition off to the lock position.
Disconnect the Transmission Control Module C2 harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance between the Mod Press Solenoid Control circuit and the
Solenoid Supply Voltage circuit in the Transmission Control Module C2 harness
connector.
Is the resistance between 4.0 and 8.0 ohms?All
Ye s!Replace the Transmission Control Module.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Replace the Mod Press Solenoid per the Service Information.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
7 The conditions necessary to set this 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.
NOTE: Check for any Technical Service Bulletins that may apply.
Were there any problems found?All
Ye s!Repair as necessary
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Test Complete.
86
TRANSMISSION - NAG1
MODULATING PRESSURE SOLENOID CIRCUIT ÐContinued
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 Turn the ignition off to the lock position.
Disconnect the TCM C2 harness connector.
Disconnect the Transmission Solenoid harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance of the Sensor Supply Voltage circuit between the TCM
connector and the Transmission Solenoid Assembly connector
Is the resistance above 5.0 ohms?All
Ye s!Repair the Sensor Supply Voltage circuit for an open.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 3
3 With the DRBIIIt, read DTCs.
NOTE: The vehicle must be driven to at least 32 Km/h (20 MPH) for this DTC
to be displayed as active.
Is the Warm up counter displayed and equal to 0?All
Ye s!Go To 4
No!Go To 12
4 Turn the ignition switch to the lock position
Disconnect the TCM C2 harness connector.
Disconnect the Transmission Solenoid Assembly harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the N2 Input Speed Sensor Signal circuit from the TCM
connector to the Transmission Solenoid Assembly connector.
Is the resistance above 5.0 ohms?All
Ye s!Repair the N2 Input Speed Sensor Signal circuit for an open.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 5
88
TRANSMISSION - NAG1
N2 INPUT SPEED SENSOR CIRCUIT ÐContinued
TEST ACTION APPLICABILITY
5 Turn the ignition off to the lock position.
Disconnect the TCM C2 harness connectors.
Disconnect the Transmission Solenoid Assembly harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the Sensor Ground circuit from the TCM C2 harness
connector to the Transmission Solenoid Assembly harness connector.
Is the resistance above 5.0 ohms?All
Ye s!Repair the Sensor Ground circuit for an open.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 6
6 Turn the ignition off to the lock position.
Disconnect the TCM C2 harness connector.
Disconnect the Transmission Solenoid Assembly harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the N2 Speed Sensor Signal circuit to all other circuits in
the Transmission Solenoid harness connector.
Is the resistance below 5.0 ohms between any other circuit?All
Ye s!Repair the N2 Speed Sensor Signal circuit for a short to other
circuit-s.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 7
7 Turn the ignition off to the lock position.
Disconnect the TCM C2 harness connector.
Disconnect the Transmission Solenoid Assembly harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance between ground and the N2 Input Speed Sensor Signal
circuit.
Is the resistance Below 5.0 ohms?All
Ye s!Repair the N2 Input Speed Sensor Signal circuit for a short to
ground.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 8
8 Turn the ignition off to the lock position.
Disconnect the TCM C2 harness connector.
Disconnect the Transmission Solenoid Assembly harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the Sensor Ground circuit to all other circuits in the
Transmission Solenoid harness connector.
Is the resistance below 5.0 ohms between any other circuit?All
Ye s!Repair the Sensor Ground circuit for a short to other circuits.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 9
89
TRANSMISSION - NAG1
N2 INPUT SPEED SENSOR CIRCUIT ÐContinued
TEST ACTION APPLICABILITY
9 Turn the ignition off to the lock position.
Disconnect the TCM C2 harness connectors.
Disconnect the Transmission Solenoid Assembly harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance between ground and the Sensor Ground circuit.
Is the resistance Below 5.0 ohms?All
Ye s!Repair the Sensor Ground circuit for a short to ground.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 10
10 Turn the ignition off to the lock position.
With the DRBIIIt/PEP Module being used as a Dual Channel Lab Scope with Miller
Special tool #6801.
Backprobe N2 Input Speed Sensor Signal circuit using Channel 1 at the TCM
harness connector.
Raise all drive wheels off the ground.
CAUTION: Properly support vehicle
Start the engine.
Place gear selector in drive and increase vehicle speed to engage 2nd gear
CAUTION: BE SURE TO KEEP HANDS AND FEET CLEAR OF ROTATING
WHEELS.
Compare the Scope Pattern on the DRBIIItwith a typical 5-volt square wave
pattern.
Does the scope pattern match a typical 5 volt square wave Signal Scope Pattern?All
Ye s!Go To 11
No!Replace the N2 Input Speed Sensor.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
11 If there are no possible causes remaining, view repair. All
Repair
Replace the Transmission Control Module.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
12 The conditions necessary to set this 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.
NOTE: Check for any Technical Service Bulletins that may apply.
Were any problems found?All
Ye s!Repair as necessary.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Test Complete.
90
TRANSMISSION - NAG1
N2 INPUT SPEED SENSOR CIRCUIT ÐContinued