Dodge Ram Truck 1500-2500-3500. Manual — part 1727

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

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?

Yes

>> Repair as necessary.

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

No

>> Test Complete.

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AUTOMATIC TRANSMISSION - 48RE - DIESEL - ELECTRICAL DIAGNOSTICS

DR/DH

P0850-P/N SWITCH PERFORMANCE (DIESEL)

DR/DH

AUTOMATIC TRANSMISSION - 48RE - DIESEL - ELECTRICAL DIAGNOSTICS

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P0850-P/N SWITCH PERFORMANCE (DIESEL) (CONTINUED)

For the Transmission circuit diagram (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE - SCHE-
MATICS AND DIAGRAMS)

For a complete wiring diagramRefer to Section 8W

•

When Monitored:
Continuously with the ignition on and engine running.

•

Set Condition:
The Transmission governor pressure set point is above a threshold while in park or the P/N switch is in drive
during an engine start.

Possible Causes

TRS CONNECTOR DAMAGE OR CORROSION

ECM CONNECTOR DAMAGE OR CORROSION

(T41) P/N POSITION SWITCH SENSE CIRCUIT OPEN

(T41) P/N POSITION SWITCH SENSE CIRCUIT SHORT TO GROUND

(T41) P/N POSITION SWITCH SENSE CIRCUIT SHORT TO ANOTHER CIRCUIT

TRANSMISSION RANGE 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 SCAN TOOL DISPLAYS P/N AND D/R IN THE CORRECT POSITION

Ignition on, engine not running.

With the scan tool, monitor the PNP switch input state.

Move the gear selector through all gear positions Park to 1st and back to Park..

Did the scan tool display P/N and D/R in the correct gear positions?

Yes

>> Go To 8

No

>> Go To 2

2.

CHECK THE TRS CONNECTOR FOR DAMAGE OR CORROSION

Turn the ignition off to the lock position.

Disconnect the Transmission Range Sensor harness connector.

Inspect the Transmission Range Sensor harness wiring and connector for damage, pushed out pins, or corrosion,
etc.

Were there any problems found?

Yes

>> Repair as necessary.

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

No

>> Go To 3

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AUTOMATIC TRANSMISSION - 48RE - DIESEL - ELECTRICAL DIAGNOSTICS

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P0850-P/N SWITCH PERFORMANCE (DIESEL) (CONTINUED)

3.

CHECK THE ECM CONNECTOR FOR DAMAGE OR CORROSION

Disconnect the ECM C2 harness connector.

Inspect the ECM wiring and connector for damage, pushed out pins, or corrosion, etc.

Were there any problems found?

Yes

>> Repair as necessary.

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

No

>> Go To 4

4.

CHECK THE (T41) P/N POSITION SWITCH SENSE CIRCUIT FOR AN OPEN

Measure the resistance of the (T41) P/N Position Switch Sense circuit
between the ECM C2 harness connector and the Transmission Range
Sensor harness connector.

Is the resistance below 5.0 ohms?

Yes

>> Go To 5

No

>> Repair the (T41) P/N Position Switch Sense circuit for an

open.

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

DR/DH

AUTOMATIC TRANSMISSION - 48RE - DIESEL - ELECTRICAL DIAGNOSTICS

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