Dodge Dakota (ND). Manual — part 1056
P0944-LOSS OF HYDRAULIC PUMP PRIME
For the Transmission circuit diagram (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE -
SCHEMATICS AND DIAGRAMS)
For a complete wiring diagram Refer to Section 8W
•
When Monitored:
If the transmission is slipping in any forward gear and all the pressure switches are not indicating pressure, a
loss of prime test is run.
•
Set Condition:
If the transmission begins to slip in a forward gear and all the pressure switch(s) that should be closed are
open a loss of prime test begins. Available elements are turned on by the PCM to see if pump prime exists.
The DTC sets if no pressure switch(s) respond.
Possible Causes
SHIFT LEVER OUT OF ADJUSTMENT
INPROPER FLUID LEVEL
CRACKED OR IMPROPERLY INSTALLED PRIMARY OIL FILTER OR SEAL
LOOSE COOLER RETURN FILTER
STUCK OR STICKING MAIN REGULATOR VALVE
TRANSMISSION OIL PUMP
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - DIAGNOSIS AND TESTING).
Theory of Operation
The Loss of prime test is used to prevent transmission defaults and erroneous fault codes during temporary loss of
pump prime that may occur with low transmission fluid under severe braking conditions, start-up, etc. and to point
towards more subtle problems such as a plugged or cracked oil filter.
The Loss of Prime DTC is set by a loss of hydraulic pressure in the transmission system. This condition, if sus-
tained, will result in the vehicle being unable to move.
Diagnostic Test
1.
SHIFT LEVER POSITION TEST
Using the scan tool, perform a Shift Lever Position test. Follow the instructions on the scan tool.
Did the Shift Lever Position Test pass?
Yes
>> Go To 2
No
>> Refer to the Transmission category and perform the appropriate symptom.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
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AUTOMATIC TRANSMISSION 545RFE - ELECTRICAL DIAGNOSTICS
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P0944-LOSS OF HYDRAULIC PUMP PRIME (CONTINUED)
2.
CHECK TO SEE IF DTC P0944 IS CURRENT
Place the gear selector in Park.
Start the engine.
The transmission must be at operating temperature prior to checking pressure. A cold transmission will give higher
readings.
Run the engine at 1500 RPM.
With the scan tool, monitor the Transmission Line Pressure.
Does the Line Pressure match the Desired Line Pressure within ± 5 psi?
No
>> Go To 6
Yes
>> Go To 3
3.
CHECK LINE PRESSURE IN DRIVE AND REVERSE
Firmly apply the brake and repeat the previous test in both Drive and the Reverse gear positions.
With the scan tool, monitor the Transmission Line Pressure.
Does the Line Pressure match the Desired Line Pressure within ± 5 psi in all gear ranges?
Yes
>> Go To 4
No
>> Go To 5
4.
REVIEW CUSTOMER COMMENTS
The conditions necessary to set this DTC are not present at this time.
Verify with the customer if a delayed engagement and/or an intermittent
9
No Drive
9
condition has occurred.
If the customers answer is
9
No
9
erase the DTC and return the vehicle to the customer.
Make sure to check for any TSBs or controller flash updates that my apply.
With the scan tool, check the EATX DTC EVENT DATA to help identify the conditions in which the DTC was set.
Has the customer experienced any delayed engagement and/or
(
No Drive
(
conditions?
Yes
>> Repair internal transmission as necessary. Replace the Transmission Oil Pump if inspection reveals no
signs of internal seal leakage. Refer to the Service Information for the proper repair procedure.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
No
>> Test Complete.
5.
DTC VERIFICATION
Read and record the DTC and the EATX DTC EVENT DATA information.
Test drive the vehicle and attempt to operate the vehicle within the parameters in which the DTC set.
With the scan tool, read DTCs.
Did any following DTCs set, P0868, P0944, P0841, P0846, P0871, P0876, or P0988?
Yes
>> Go To 6
No
>> Test Complete.
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AUTOMATIC TRANSMISSION 545RFE - ELECTRICAL DIAGNOSTICS
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P0944-LOSS OF HYDRAULIC PUMP PRIME (CONTINUED)
6.
CHECK TRANSMISSION OIL FILTER
Remove and inspect the Transmission Oil Pan per the Service Information.
Remove and inspect the Primary Oil Filter per the Service Information.
Inspect the oil filter seal for damage and proper installation.
Does the Oil Pan contain excessive debris and/or is the Oil Filter plugged or seal damaged?
Yes
>> Repair the cause of the plugged transmission oil filter or excessive debris. Check the Transmission Oil
Filter seal for improper installation onto filter neck instead of into the pump bore, not fully seated against
pump housing, filter neck not engaged into pump. Repair as necessary.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
No
>> Repair the Transmission Oil Pump as necessary. Check for a stuck main regulator valve and clean if
necessary. Refer to the Service Information for the proper repair procedure.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
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AUTOMATIC TRANSMISSION 545RFE - ELECTRICAL DIAGNOSTICS
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P0987-4C HYDRAULIC PRESSURE TEST
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AUTOMATIC TRANSMISSION 545RFE - ELECTRICAL DIAGNOSTICS
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