Dodge Ram Truck 1500-2500-3500. Manual — part 1726

P0748-PRESSURE SOL CONTROL/TRANS RELAY CIRCUITS (DIESEL) (CONTINUED)

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 ECM C2 harness connector.

NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance of the (T118) Governor Pressure Solenoid
Control circuit between the Transmission Solenoid Assembly harness
connector and the ECM C2 harness connector.

Is the resistance below 5.0 ohms?

Yes

>> Go To 5

No

>> Repair the (T118) Governor Pressure Solenoid Control cir-

cuit for an open.

Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)

5.

CHECK THE (T118) GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT FOR A SHORT TO GROUND

Measure the resistance between ground and the (T118) Governor
Pressure Solenoid Control circuit.

Is the resistance below 5.0 ohms?

Yes

>> Repair the (T118) Governor Pressure Solenoid Control cir-

cuit for a short to ground.

Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)

No

>> Go To 6

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AUTOMATIC TRANSMISSION - 48RE - DIESEL - ELECTRICAL DIAGNOSTICS

DR/DH

P0748-PRESSURE SOL CONTROL/TRANS RELAY CIRCUITS (DIESEL) (CONTINUED)

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 Con-
trol circuit.

Is the voltage above 0.5 volt?

Yes

>> Repair the (T118) Governor Pressure Solenoid Control cir-

cuit for a short to voltage.

Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)

No

>> Go To 7

7.

CHECK THE (T118) GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT FOR A SHORT TO
ANOTHER CIRCUIT

Turn the ignition off to the lock position.

Remove the Transmission Control Relay.

Measure the resistance between the (T118) Governor Pressure Sole-
noid Control circuit and all other circuits in the Transmission Solenoid
Assembly harness connector.

Is the resistance below 5.0 ohms between the (T118) Governor
Pressure Solenoid Control circuit and any other circuit in the
Transmission Solenoid Assembly harness connector?

Yes

>> Repair the (T118) Governor Pressure Solenoid Control cir-

cuit 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 8

DR/DH

AUTOMATIC TRANSMISSION - 48RE - DIESEL - ELECTRICAL DIAGNOSTICS

21 - 837

P0748-PRESSURE SOL CONTROL/TRANS RELAY CIRCUITS (DIESEL) (CONTINUED)

8.

CHECK THE GOVERNOR PRESSURE SOLENOID

Remove the Transmission Oil Pan per the Service Information. (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE/FLUID - STANDARD PROCEDURE)

Check all internal wiring pertaining to the Governor Pressure Solenoid for an open, short, and bent or broken ter-
minals.

If no internal wiring problems are found, replace the Governor Pressure Solenoid per the Service Information. (Refer
to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE/GOVERNOR PRESSURE SENSOR - REMOVAL)

Drive the vehicle performing multiple upshifts and downshifts.

With the scan tool, read Transmission DTCs.

Does the DTC reset?

Yes

>> 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 attention to all power and ground cir-
cuits. If no problems are found, replace and program the ECM per the Service Information. (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)

No

>> Test Complete.

Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)

9.

CHECK THE FUSED B(+) CIRCUIT

Turn the ignition off to the lock position.

Remove the Transmission Control Relay.

Ignition on, engine not running.

Using a 12-volt test light connected to ground, check the Fused B(+)
circuit in the Transmission Control Relay connector.

Does the test light illuminate brightly?

Yes

>> Go To 10

No

>> Repair the Fused B(+) circuit for an open. If the fuse is

open, make sure to check for a short to ground.

Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)

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AUTOMATIC TRANSMISSION - 48RE - DIESEL - ELECTRICAL DIAGNOSTICS

DR/DH

P0748-PRESSURE SOL CONTROL/TRANS RELAY CIRCUITS (DIESEL) (CONTINUED)

10.

CHECK THE (T16) TRANSMISSION CONTROL RELAY OUTPUT CIRCUIT FOR A SHORT TO GROUND

Turn the ignition off to the lock position.

Disconnect the Transmission Solenoid Assembly harness connector.

Measure the resistance between ground and the (T16) Transmission
Control Relay Output circuit.

Is the resistance below 5.0 ohms?

Yes

>> Repair the (T16) Transmission Control Relay Output circuit

for a short to ground.

Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)

No

>> Go To 11

11.

CHECK THE (T16) TRANSMISSION CONTROL RELAY OUTPUT CIRCUIT OPEN

Connect a jumper wire between Fused B(+) and the (T16) Transmis-
sion Control Relay Output circuit in the Transmission Control Relay
connector.

Ignition on, engine not running.

Using a 12-volt test light connected to ground, check the (T16) Trans-
mission Control Relay Output circuit in the Transmission Solenoid
Assembly harness connector.

Does the test light illuminate brightly?

Yes

>> Replace the Transmission Control Relay.

Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)

No

>> Replace the (T16) Transmission Control Relay Output cir-

cuit for an open.

Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCE-
DURE)

DR/DH

AUTOMATIC TRANSMISSION - 48RE - DIESEL - ELECTRICAL DIAGNOSTICS

21 - 839