Page 3652 of 5267
P0748-PRESSURE SOL CONTROL/TRANS RELAY CIRCUITS (DIESEL)
For a complete wiring diagramRefer to Section 8W
Page 3654 of 5267

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.
Page 3676 of 5267
P0882-TRANS 12 VOLT SUPPLY RELAY CONTROL CIRCUIT LOW (DIESEL)
For a complete wiring diagramRefer to Section 8W
Page 3677 of 5267

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
Page 3680 of 5267
P0883-TRANS 12 VOLT SUPPLY RELAY CONTROL CIRCUIT HIGH (DIESEL)
For a complete wiring diagramRefer to Section 8W
Page 3685 of 5267

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.
Page 3686 of 5267

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)
Page 3695 of 5267

5.CHECK THE (T9) 3-4 SHIFT SOLENOID CONTROL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT
Turn the ignition off to the lock position.
Disconnect the ECM C1 and C2 harness connectors.
Disconnect the Transmission Solenoid Assembly harness connector.
Remove the Transmission Control Relay.
Measure the resistance between the (T9) 3-4 Shift Solenoid Control cir-
cuit and all other circuits in the Transmission Solenoid Assembly har-
ness connector.
Is the resistance below 5.0 ohms between the (T9) 3-4 Shift
Solenoid Control circuit and anyother circuit(s) in the ECM C1
and C2 harness connectors?
Ye s>>
Repair the 3-4 Shift Solenoid Control circuit for a short to
another circuit(s).
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 6
6.CHECK THE 3-4 SOLENOID
Turn the ignition off to the lock position.
Disconnect the Transmission Solenoid Assembly harness connector.
Ignition on, engine not running.
With the scan tool, actuate the 3-4 (Overdrive) Solenoid.
Using a 12-volt test light connected to 12-volts, check the 3-4 Solenoid
Control circuit in the TransmissionSolenoid Assembly harness connec-
tor.
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 7
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)