Theory of Operation
The Governor Pressure Sensor is used by the ECM to adjust the Governor Pressure to a desired level for shifts in
first, second, and third gear. If the ECM detects the monitored sense voltage is greater than or less than a prede-
termined specification, the ECM will set the desired DTC.
When Monitored:
Continuously with the ignition on and the engine running.
Set Condition:
This DTC will set if the monitored voltage from the Governor Pressure Sensor drops below 0.12 volts for the
period of 8.5 seconds.
Possible Causes
PARK NEUTRAL DTC PRESENT OR OTHER TRANSMISSION DTC’S PRESENT
(T38) GOVERNOR PRESSURE SENSOR SIGNAL CIRCUIT SHORT TO GROUND
(T38) GOVERNOR PRESSURE SENSOR SIGNAL CIRCUIT SHORT TO OTHER CIRCUITS
TRANSMISSION SOLENOID ASSEMBLY
GOVERNOR PRESSURE SENSOR
ENGINE CONTROL MODULE
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
Diagnostic Test
1.CHECK IF THE DTC IS CURRENT
Ignition on, engine not running.
With the scan tool, read Engine DTCs.
Record the Freeze Frame data for the reported DTC.
With the scan tool, erase DTCs.
Turn the ignition off to the lock position.
Using the Freeze Frame data recorded earlier, try to duplicate the conditions in which the DTC originally set.
NOTE: It may be necessary to road test the vehicle to duplicate the originalset conditions.
With the scan tool, read Engine DTCs.
Did the DTC reset?
Ye s>>
Go To 2
No>>
Go To 7
2.CHECK FOR OTHER TRANSMISSION DTC’S PRESENT
Are there any Park/Neutral or other Transmission DTCs present?
Ye s>>
Refer to the Transmission category and perform the appropriate symptom(s). If a Park/Neutral DTC is
present, perform its respective test first.
No>>
Go To 3
5.CHECK THE TRANSMISSION SOLENOID ASSEMBLY
Reconnect the Transmission Solenoid Assembly harness connector.
Remove the Transmission Oil Pan perthe Service Information. (Refer to
21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE/FLUID -
STANDARD PROCEDURE)
Disconnect the Governor Pressure/Transmission Temperature Sensor
connector (inside transmission).
Measure the resistance between the (T38) Governor Pressure Sensor
Signal circuit and all other circuits in the ECM C1 and C2 harness con-
nectors.
Is the resistance below 100k ohms between the (T38) Governor
Pressure Sensor Signal circuit any other circuits in the ECM
C2 harness connector?
Ye s>>
Replace the Transmission Solenoid Assembly per the Ser-
vice Information.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 6
6.CHECK THE GOVERNOR PRESSURE SENSOR SENSOR
Turn the ignition on.
With the scan tool, erase DTCs.
Connect a jumper wire between the (T38) Governor Pressure Sensor
Signal circuit and the (F856) 5-volt Supply circuit in the Governor Pres-
sure Sensor connector.
With the scan tool, read DTCs.
Did the DTC P0868 set?
Ye s>>
Inspect the Governor Pressure Sensor wiring for damage. If
no problems are found, replace the Governor Pressure Sen-
sor per the Service Information.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Using the schematics as a guide, check the Engine Control Module (ECM) pins, terminals, and connec-
tors for corrosion, damage, or terminal push out. Pay particular attentiontoallpowerandgroundcir-
cuits. If no problems are found, replace and program the ECM per the ServiceInformation. (Refer to 8
- ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
Theory of Operation
The Transmission Control Output from the Totally Integrated Power Module(TIPM) supplies power to the TCC,
Overdrive, and Governor Pressure Solenoids when in normal operating mode. The Transmission Control circuit is
constantly monitored by the ECM. If the expected state of the TransmissionControl circuit is different then the
expected state, a corresponding DTC will set and the ECM will de-energize the Transmission Control and place the
transmission in Limp-in.
When Monitored:
Continuously with the Ignition on.
Set Condition:
This DTC will set if the ECM monitored voltage of the Transmission Control Relay Control circuit is different
than the expected voltage for the period 3.0 seconds.
Possible Causes
(T515) TRANSMISSION CONTROL CIRCUIT OPEN
(T515) TRANSMISSION CONTROL CIRCUIT SHORT TO GROUND
(T515) TRANSMISSION CONTROL CIRCUIT SHORT TO ANOTHER CIRCUIT
TOTALLY INTEGRATED POWER MODULE (TIPM)
ENGINE CONTROL MODULE
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
1.CHECK IF THE DTC IS CURRENT
Ignition on, engine not running.
With the scan tool, read Engine DTCs.
Record the Freeze Frame data for the reported DTC.
With the scan tool, erase DTCs.
Turn the ignition off to the lock position.
Using the Freeze Frame data recorded earlier, try to duplicate the conditions in which the DTC originally set.
NOTE: It may be necessary to road test the vehicle to duplicate the originalset conditions.
With the scan tool, read Engine DTCs.
Did the DTC reset?
Ye s>>
Go To 2
No>>
Go To 5
2.CHECK THE TIPM FOR CODES
Ignition on, engine not running.
With the scan tool, read TIPM DTCs.
Are there any TIPM DTCs?
Ye s>>
Refer to the Transmission category and perform the appropriate symptom(s).
No>>
Go To 3
3.CHECK THE (T515) TRANSMISSION CONTROL CIRCUIT
Turn the ignition off to the lock position.
Disconnect the TIPM C1 harness connector.
Ignition on, engine not running.
Using the scan tool in the ECM, actuate the Transmission.
Using a 12-volt test light connected to ground, check the (T515) Trans-
mission Control circuit at the TIPM C1 harness connector.
Does the test light cycle on and off and illuminate brightly?
Ye s>>
Using the schematics as a guide, check the Totally Inte-
grated Power Module (TIPM) pins, terminals, and connec-
tors for corrosion, damage, or terminal push out. Pay
particular attention to all power and ground circuits. If no
problems are found, replace and program the TIPM per the
Service Information.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 4
4.CHECK THE (T515) TRANSMISSION CONTROL CIRCUIT FOR AN OPEN
Turn the ignition off to the lock position.
Disconnect the ECM C2 harness connector.
Connect a jumper wire between cavity 5 in the ECM C2 harness con-
nector and ground.
Using a 12-volt test light connected to 12 volts, check the (T515) Trans-
mission Control circuit at the TIPM C1 harness connector.
Does the test light illuminate brightly?
Ye s>>
Using the schematics as a guide, check the Engine Control
Module (ECM) pins, terminals, and connectors for corrosion,
damage, or terminal push out. Pay particular attention to all
power and ground circuits. If no problems are found,
replace and program the ECM per the Service Information.
(Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/ENGINE CONTROL MODULE - REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Repair the (T515) Transmission Control circuit for an open.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
Theory of Operation
The Transmission Control Output from the Totally Integrated Power Module(TIPM) supplies power to the TCC,
Overdrive, and Governor Pressure Solenoids when in normal operating mode. The Transmission Control circuit is
constantly monitored by the ECM. If the expected state of the TransmissionControl circuit is different then the
expected state, a corresponding DTC will set and the ECM will de-energize the Transmission Control and place the
transmission in Limp-in.
When Monitored:
Continuously with the ignition on.
Set Condition:
This DTC will set if the ECM monitored voltage of the Transmission Control circuit is different than the
expected voltage for the period 3.0 seconds.
Possible Causes
(T515) TRANSMISSION CONTROL CIRCUIT SHORT TO VOLTAGE
(T515) TRANSMISSION CONTROL CIRCUIT SHORT TO ANOTHER CIRCUIT
ENGINE CONTROL MODULE
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
Diagnostic Test
1.CHECK IF THE DTC IS CURRENT
Ignition on, engine not running.
With the scan tool, read Engine DTCs.
Record the Freeze Frame data for the reported DTC.
With the scan tool, erase DTCs.
Turn the ignition off to the lock position.
Using the Freeze Frame data recorded earlier, try to duplicate the conditions in which the DTC originally set.
NOTE: It may be necessary to road test the vehicle to duplicate the originalset conditions.
With the scan tool, read Engine DTCs.
Did the DTC reset?
Ye s>>
Go To 2
No>>
Go To 5
2.CHECK THE TIPM FOR CODES
Ignition on, engine not running.
With the scan tool, read TIPM DTCs.
Are there any TIPM DTCs?
Ye s>>
Refer to the Transmission category and perform the appropriate symptom(s).
No>>
Go To 3
3.CHECK THE (T515) TRANSMISSION CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
Turn the ignition off to the lock position.
Disconnect the TIPM C1 harness connector.
Ignition on, engine not running.
Using a volt meter connected to ground, check the (T515) Transmission
Control circuit at the TIPM C1 harness connector.
Is the voltage above 1.0 volts?
Ye s>>
Go To 4
No>>
Go To 5
4.CHECK THE (T515) TRANSMISSION CONTROL CIRCUIT
Turn the ignition off to the lock position.
Disconnect the TIPM C1 harness connector.
Disconnect the ECM C2 harness connector.
Ignition on, engine not running.
Using a volt meter connected to ground, check the (T515) Transmission
Control circuit at the TIPM C1 harness connector.
Is the voltage above 1.0 volts?
Ye s>>
Repair the (T515) Transmission Control circuit for a short to
voltage.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Using the schematics as a guide, check the Engine Control
Module (ECM) pins, terminals, and connectors for corrosion,
damage, or terminal push out. Pay particular attention to all
power and ground circuits. If no problems are found,
replace and program the ECM per the Service Information.
(Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/ENGINE CONTROL MODULE - REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
Theory of Operation
The 3-4 Solenoid is used the engage the gear change form 3rd gear to 4th gear.
The solenoids used in transmission applications are attached to valves which can be classified as normally open or
normally closed. The normally open solenoid valve is defined as a valve which allows hydraulic flow when no cur-
rent or voltage is applied to the solenoid. The normally closed solenoid valve is defined as a valve which does not
allow hydraulic flow when no current or voltage is applied to the solenoid.These valves perform hydraulic control
functions for the transmission and must therefore be durable and tolerantof dirt particles. For these reasons, the
valves have hardened steel poppets and ball valves. The solenoids operatethe valves directly, which means that
the solenoids must have very high outputs to close the valves against the sizable flow areas and line pressures
found in current transmissions. Fastresponse time is also necessary to ensure accurate control.
When Monitored:
Continuously with ignition on.
Set Condition:
This code will set if the voltage detected on the 3-4 Shift Solenoid Controlcircuit at the ECM is different then
the expected voltage. Note: To clear this DTC it is necessary to drive the vehicle at a sustained speed which
would allow the TCC and/or Overdrive Clutch to operate
Possible Causes
TRANSMISSION CONTROL DTC PRESENT
(T16) TRANSMISSION CONTROL OUTPUT CIRCUIT OPEN
(T16) TRANSMISSION RELAY OUTPUT CIRCUIT SHORT TO GROUND
(T9) 3-4 SOLENOID CONTROL CIRCUIT SHORT TO GROUND
(T9) 3-4 SOLENOID CIRCUIT SHORT TO OTHER CIRCUITS
(T9) 3-4 SOLENOID CONTROL CIRCUIT OPEN
3-4 SHIFT SOLENOID
TOTALLY INTEGRATED POWER MODULE (TIPM)
ENGINE CONTROL MODULE
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
Diagnostic Test
1.CHECK FOR TRANSMISSION CONTROL RELAY DTCS
Ignition on, engine not running.
With the scan tool, read Engine DTCs.
Are there any Transmission Control Relay DTCs present?
Ye s>>
Refer to the Transmission category, and perform the appropriate symptom(s).
No>>
Go To 2
2.CHECK IF THE DTC IS CURRENT
Ignition on, engine not running.
With the scan tool, read Engine DTCs.
Record the Freeze Frame data for the reported DTC.
With the scan tool, erase DTCs.
Turn the ignition off to the lock position.
Using the Freeze Frame data recorded earlier, try to duplicate the conditions in which the DTC originally set.
NOTE: It may be necessary to road test the vehicle to duplicate the originalset conditions.
With the scan tool, read Engine DTCs.
Did the DTC reset?
Ye s>>
Go To 3
No>>
Go To 13
3.CHECK THE (T16) TRANSMISSION CONTROL RELAY OUTPUT CIRCUIT
Ignition on, engine not running.
With the scan tool, actuate the Transmission Control Output in the
ECM.
Using a 12-volt test light connected to ground, back probe the (T16)
Transmission Control Output circuit at the TIPM C10 harness connector.
NOTE: The test light must illuminate brightly. Compare the bright-
ness to that of a direct connection to the battery.
Does the test light cycle on and off and illuminate brightly?
Ye s>>
Go To 4
No>>
Go To 10
4.CHECK THE (T16) TRANSMISSION CONTROL RELAY OUTPUT CIRCUIT
Ignition on, engine not running.
With the scan tool, actuate the Transmission Control Output in the
ECM.
Using a 12-volt test light connected to ground, back probe the (T16)
Transmission Control Output circuit at the Transmission Solenoid
Assembly harness connector.
NOTE: The test light must illuminate brightly. Compare the bright-
ness to that of a direct connection to the battery.
Does the test light cycle on and off and illuminate brightly?
Ye s>>
Go To 5
No>>
Repair the (T16) Transmission Control Output Circuit for an
open.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)