Dodge Ram Truck 1500-2500-3500. Manual — part 1728

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

5.

CHECK THE (T41) P/N POSITION SWITCH SENSE CIRCUIT FOR A SHORT TO GROUND

Measure the resistance between ground and the (T41) P/N Position
Switch Sense circuit.

Is the resistance greater then 100k ohms?

Yes

>> Go To 6

No

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

short to ground.

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

6.

CHECK THE (T41) P/N POSITION SWITCH SENSE CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT

Measure the resistance between the (T41) P/N Position Switch Sense
circuit and all other circuits in the ECM C1 and C2 harness connec-
tors.

Is the resistance greater 100k ohms between the (T41) P/N
Position Switch Sense circuit and any other circuit(s) in the
ECM C1 and C2 harness connectors?

Yes

>> Go To 7

No

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

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AUTOMATIC TRANSMISSION - 48RE - DIESEL - ELECTRICAL DIAGNOSTICS

DR/DH

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

7.

CHECK THE TRANSMISSION RANGE SENSOR

Reconnect the Transmission Range Sensor harness connector.

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

While moving the gear selector through the gear positions, measure
the resistance between ground and the (T41) P/N Position Switch
Sense circuit in the ECM harness connector.

NOTE: The circuit is grounded in Park and Neutral and open in
the other positions.

Did the display change from above 100k ohms (open) to below
5.0 ohms (grounded)?

Yes

>> Using the schematics as a guide, check the Engine Con-

trol Module (ECM) pins, terminals, and connectors for cor-
rosion, 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 MODULES/ENGINE CONTROL MODULE -
REMOVAL)

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

No

>> Replace the Transmission Range Sensor per Service Information. (Refer to 21 - TRANSMISSION/

TRANSAXLE/AUTOMATIC - 48RE/TRANSMISSION RANGE SENSOR - REMOVAL)

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

8.

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.

DR/DH

AUTOMATIC TRANSMISSION - 48RE - DIESEL - ELECTRICAL DIAGNOSTICS

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P0868-GOVERNOR PRESSURE SENSOR VOLTS TOO HI (DIESEL)

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AUTOMATIC TRANSMISSION - 48RE - DIESEL - ELECTRICAL DIAGNOSTICS

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P0868-GOVERNOR PRESSURE SENSOR VOLTS TOO HI (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

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 when the monitored sense voltage from the Governor Pressure Sensor is above 4.89 volts
for the period of 8.5 seconds.

Possible Causes

OTHER TRANSMISSION DTC’S PRESENT

PARK NEUTRAL DTC PRESENT

(T38) GOVERNOR PRESSURE SENSOR SIGNAL CIRCUIT OPEN

(K900) SENSOR GROUND CIRCUIT OPEN

(T38) GOVERNOR PRESSURE SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE

(T38) GOVERNOR PRESSURE SENSOR SIGNAL CIRCUIT SHORT TO ANOTHER CIRCUIT

(T38) GOVERNOR PRESSURE SENSOR SIGNAL CIRCUIT OPEN INSIDE TRANSMISSION

(K900) SENSOR GROUND CIRCUIT OPEN INSIDE TRANSMISSION

(T38) GOVERNOR PRESSURE SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE INSIDE TRANSMISSION

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 original set conditions.
With the scan tool, read Engine DTCs.

Did the DTC reset?

Yes

>> Go To 2

No

>> Go To 11

DR/DH

AUTOMATIC TRANSMISSION - 48RE - DIESEL - ELECTRICAL DIAGNOSTICS

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