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
PCM.
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 9
4.CHECK THE (T118) GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT FOR AN OPEN
Turn the ignition off to the lock position.
Disconnect the Transmission Solenoid Assembly harness connectors.
Disconnect the PCM C2 harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance of the (T118) Governor Pressure Solenoid Con-
trol circuit between the Transmission Solenoid Assembly harness con-
nector and the PCM C2 harness connector.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 5
No>>
Repair the (T118) Governor Pressure Solenoid Control cir-
cuit for an open.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)
5.CHECK THE (T118) GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT FOR A SHORT TOGROUND
Measure the resistance between ground and the (T118) Governor Pres-
sure Solenoid Control circuit.
Is the resistance below 5.0 ohms?
Ye s>>
Repair the (T118) Governor Pressure Solenoid Control cir-
cuit for a short to ground.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 6
6.CHECK THE (T118) GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT SHORT TO VOLTAGE
Ignition on, engine not running.
Measure the voltage of the (T118) Governor Pressure Solenoid Control
circuit.
Is the voltage above 0.5 volt?
Ye s>>
Repair the (T118) Governor Pressure Solenoid Control cir-
cuit for a short to voltage.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 7
9.CHECK THE (T16) TRANSMISSION CONTROL OUTPUT CIRCUIT FOR OPEN.
Ignition on, engine not running.
Using the scan tool in the TIPM, actuate the Transmission.
Using a 12-volt test light connected to ground, back probe the (T16)
Transmission Control Output circuit at the TIPM C10 harness connector.
Does the test light illuminate brightly?
Ye s>>
Go To 10
No>>
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 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)
10.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 PCM, actuate the Transmission.
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 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 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 11
11 .CHECK THE (T515) TRANSMISSION CONTROL CIRCUIT FOR AN OPEN
Turn the ignition off to the lock position.
Disconnect the PCM C2 harness connector.
Connect a jumper wire between cavity 30in the PCM 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 (PCM) 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 PCM per the Service Information.
(Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/ENGINE CONTROL MODULE - REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Repair the (T515) Transmission Control circuit for an open.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)
12.INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
Use the Freeze Frame Data to help duplicate the conditions in which the DTC originally set. Pay particular attention
to the DTC set conditions, such as, VSS, MAP, ECT, and Load
Using the schematics as a guide, visually inspect the related wiring harness. Look for any chafed, pierced, pinched,
or partially broken wires.
Visually inspect the related wiring harness connectors. Look for broken,bent, pushed out, or corroded terminals.
Wiggle the wiring and connectors while checking for any possible open or shorted circuits.
Check for any Service Information Tune-ups or Technical Service Bulletins that may apply.
Were there any problems found?
Ye s>>
Repair as necessary.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Te s t C o m p l e t e .
Theory of Operation
The Tow/haul Overdrive OFF (control) Switch is located in the shift lever arm. The switch is a momentary contact
device that signals the PCM to toggle current status of the overdrive function. At ignition on, overdrive operation is
allowed. Pressing the Tow/Haul Overdrive Off switch once causes the Tow/haul Overdrive OFF mode to be entered
and the Tow/Haul lamp to be illuminated. Pressing the switch a second time causes normal overdrive operation to
be restored and the Tow/haul lamp to be turned off. The Tow/haul Overdrive OFF mode defaults to ON after the
ignition switch is cycled OFF and ON. Thenormal position for the control switch is the ON position. The switch must
be in this position to energize the solenoid and allow a 3-4 upshift. The control switch indicator light illuminates only
when the Tow/haul Overdrive Off switch is turned to the OFF position, or when illuminated by the transmission con-
trol module.
When Monitored:
The engine must have been running for at minimum of 10 seconds. The circuit is tested every 440ms.
Set Condition:
This DTC will set if the Tow/Haul Overdrive Off Switch Sense circuit is heldlow for 5 minutes or more from the
time of switch closure or ignition on with the engine running.
Possible Causes
TOW/HAUL OVERDRIVE OFF SWITCH SENSE CIRCUIT SHORT TO GROUND
TOW/HAUL OVERDRIVE OFF SWITCH
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.TOW/HAUL OVERDRIVE OFF SWITCH SENSE CIRCUIT SHORT TO GROUND
Turn the ignition off.
Disconnect the PCM C3 harness connector.
Disconnect the Tow/Haul OverdriveOff switch harness connector.
Measure the resistance between ground and the Tow/Haul Overdrive
Off switch sense circuit in the PCM C3 harness connector.
Is the resistance below 5.0 ohms?
Ye s>>
Repair the Tow/Haul Overdrive Off switch sense circuit for a
short to ground.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 2
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 DTC will set if the voltage detected on the 3-4 Shift Solenoid Control circuit at the PCM 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 OUTPUT DTC PRESENT
(T9) 3-4 SOLENOID CONTROL CIRCUIT OPEN
(T16) TRANSMISSION CONTROL OUTPUT CIRCUIT OPEN
(T9) 3-4 SOLENOID CONTROL CIRCUIT SHORT TO VOLTAGE
(T9) 3-4 SOLENOID CONTROL CIRCUIT SHORT TO GROUND
(T16) TRANSMISSION RELAY OUTPUT CIRCUIT SHORT TO GROUND
(T9) 3-4 SOLENOID CIRCUIT SHORT TO OTHER CIRCUITS
TOTALLY INTEGRATED POWER MODULE
3-4 SHIFT SOLENOID
POWERTRAIN 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 THERE ANY TRANSMISSION CONTROL DTCS PRESENT
Ignition on, engine not running.
With the scan tool, read Engine DTCs.
Are there any TIPM TCM Power Control Circuit DTCs also 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 12
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
PCM.
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 3-4 SHIFT SOLENOID
With the scan tool, actuate the Overdrive (3-4) Solenoid.
Using a 12-volt test light connected to 12-volts, check the (T9) 3-4 Shift
Solenoid Control circuit in the Transmission Solenoid Assembly harness
connector.
Does the test light cycle on and off and illuminate brightly?
Ye s>>
Check all internal wiring pertaining to the 3-4 Shift Solenoid
for an open, short, and bent or broken terminals. If no inter-
nal wiring problems are found, replace the Transmission
Solenoid Assembly per the Service Information. (Refer to 21
- TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE/
VA LV E B O D Y - R E M O VA L )
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 5
5.CHECK THE (T9) 3-4 SOLENOID CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
Turn the ignition off to the lock position.
Disconnect the PCM C1 and C2 harness connectors.
Ignition on, engine not running.
Measure the voltage of the (T9) 3-4 Solenoid Control circuit.
Is the voltage above 0.5 volts?
Ye s>>
Repair the (T9) 3-4 Solenoid Control circuit for a short to
voltage.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 6
6.CHECK THE (T9) 3-4 SOLENOID CONTROL CIRCUIT FOR AN OPEN
Turn the ignition off to the lock position.
Measure the resistance of the (T9) 3-4 Solenoid Control circuit between
the Transmission Solenoid Assembly harness connector and the PCM
C2 harness connector.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 7
No>>
Repair the (T9) 3-4 Solenoid Control circuit for an open.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)