P1736-GEAR RATIO ERROR IN 2ND PRIME

For a complete wiring diagram Refer to Section 8W.

Theory of Operation


The transmission system uses two speed sensors, one to measure input RPM and one to measure output RPM. These inputs are essential for proper transmission operation. Therefore, the integrity of this data is verified through the following checks:

1) When in gear, if the gear ratio does not compare to a known gear ratio, the corresponding in-gear trouble code is set (DTCs P0731-36 and P1736).

2) An excessive change in input or output speeds indicating signal intermittent will result in the DTCs P0715 and/or P0720 being set.

3) If the common speed sensor ground circuit is lost, both sensor inputs will read the signal from the input speed sensor at idle in neutral. Since the input speed sensor reads 60 teeth from the input clutch hub and the output speed sensor reads 30 teeth from the park gear, the result is an apparent speed ratio of 1:2 and may cause the DTC P1794 to set when at a stop.


  • When Monitored:

    Continuously with the ignition on, engine running, with the transmission in gear.

  • Set Condition:

    If the ratio of the Input RPM to the Output RPM does not match the current gear ratio. This DTC can take up to five minutes of problem identification before illuminating the MIL


Possible Causes
 
RELATED DTC'S PRESENT
 
INPUT SPEED SENSOR OR WIRING
 
LOW FLUID LEVEL
 
CRACKED OR MIS-INSTALLED PRIMARY OIL FILTER OR SEAL
 
WORN SOLENOID SWITCH VALVE OR PLUGS
 
STUCK OR STICKING MAIN REGULATOR VALVE
 
BURNED UD OR 4C CLUTCH
 
CUT 4C OR UD PISTON SEAL
 
BROKEN 4C PISTON CASTING
 
BROKEN OR MISSING 4C BLEED ORIFICE
 
BROKEN OR MISSING UD BLEED ORIFICE
 
CUT 4C OR UD ACCUMULATOR PISTON SEAL
 
CRACKED 4C OR UD ACCUMULATOR PISTON
 
TRANSMISSION SOLENOID/TRS ASSEMBLY
 
BROKEN WELD - REACTION CARRIER TO REVERSE SUN GEAR
 
MISSING TEETH ON INPUT CLUTCH HUB TONE WHEEL
 


Always perform the 45RFE/545RFE Pre-Diagnostic Troubleshooting Procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)



Diagnostic Test

1.DETERMINING IF RELATED DTC'S ARE PRESENT



Are any Transmission: solenoid, line pressure, speed sensor, or loss of prime DTCs present?

Yes
  • Refer to appropriate symptom in the Transmission category. Perform the test for P0944-LOSS OF PRIME first if it is present.


No
  • Go To 2

2.CHECK DTC EVENT DATA


NOTE: Make sure to record all DTC EVENT DATA stored in the scan tool for future reference in this test procedure.



Does the DTC EVENT DATA display information for the DTC P1736?

Yes
  • Go To 3


No
  • Go To 6

3.CHECK RPM IN DTC EVENT DATA



Does the Input RPM read zero?

Yes
  • Check the input speed sensor and wiring. Refer to test P0715 and diagnose as if the DTC is current.


No
  • Go To 4

4.CHECK LINE PRESSURE READING



Is the line pressure reading more than 10 psi below the desired line pressure?

Yes
  • Go To 5


No
  • Go To 6

5.PLUGGED TRANSMISSION OIL FILTER




NOTE: Make sure the Primary Transmission Oil Filter and/or seal is not cracked or split.



Does the Oil Pan contain excessive debris and/or is the Primary Oil Filter cracked or plugged?

Yes


No

6.CHECK TO SEE IF DTC P1736 IS CURRENT



CAUTION: Do not overheat the transmission.


NOTE: If the 4C clutch is faulty, the overrunning clutch will hold and the slip test will pass. The 2nd Prime Gear Clutch Test will not detect a faulty 4C clutch. However, it will detect a faulty UD clutch.



Did the clutch test pass, did the Input Speed remain at zero?

Yes
  • Go To 7


No
  • Go To 9

7.CHECK FOR INTERMITTENT OPERATION





Were there any problems found?

Yes


No
  • Go To 8

8.CHECK FOR SLIPPAGE





Is there an obvious slippage noticed in 4th or 2nd prime gears, or runaway on the 4-2 shift?

Yes


No

9.UD CLUTCH HYDRAULIC CIRCUIT



NOTE: The UD clutch passage contains a small bleed orifice, a small amount of air leakage is normal.



Were there any problems found, excessive debris and/or excessive air leakage in the UD clutch hydraulic circuit?

Yes


No

10.UD ACCUMULATOR PISTON



Were there any problems found?

Yes
  • Repair as necessary. Refer to the Service Information for proper repair procedures.


No

11.EXCESSIVE DEBRIS



NOTE: The 4C clutch passage contains a small bleed orifice, a small amount of air leakage is normal.



Were there any problems found, excessive debris, improperly assembled 4C clutch and/or excessive air leakage in the 4C clutch hydraulic circuit?

Yes


No

12.4C ACCUMULATOR





Were there any problems found?

Yes


No

13.CHECK FOR BROKEN REVERSE SUN GEAR WELD






Is the reaction carrier turning faster than the drive shell?

Yes


No

14.CHECK IF DTC RESET


Did the DTC P1736 reset during the road test?

Yes


No

15.LIST OF POSSIBLE CAUSES










View repair

Repair

16.INTERMITTENT DTC





Where there any problems found?

Yes


No
  • Test Complete.