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 P0716 and/or P0721 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.



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

With the scan tool, check for other transmission DTCs.

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

Yes


No

2. CHECK DTC EVENT DATA

With the scan tool, read and record the 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


No

3. CHECK RPM IN DTC EVENT DATA

Refer to the DTC EVENT DATA recorded earlier.

Does the Input rpm read zero?

Yes


No

4. CHECK LINE PRESSURE READING

Refer to the DTC EVENT DATA recorded earlier.

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

Yes


No

5. PLUGGED TRANSMISSION OIL FILTER

Turn the ignition off to the lock position.
Remove and inspect the Transmission Oil Pan for excessive debris per the Service Information.
Remove and inspect the Primary Oil Filter per the Service Information.

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

With the scan tool, perform the 2nd Prime Gear Clutch Test. Follow the instructions on the scan tool.
Increase the throttle angle, TPS Degree, to 30 degrees for no more than a few seconds.

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


No

7. CHECK FOR INTERMITTENT OPERATION

Check the Shifter adjustment per the Service Information.
Intermittent gear ratio DTCs can be set by problems in the Input and Output Speed Sensor circuits and/or Speed Sensor Ground circuit.
Check the Speed Sensor wiring and connectors for good connection, then perform a wiggle test using the Transmission Simulator, Miller tool #8333.

Were there any problems found?

Yes


No

8. CHECK FOR SLIPPAGE

With the scan tool, erase Transmission DTCs.
Road test the vehicle.
During the road test, operate in 4th gear, and perform kickdown shifts from 4th to 2nd (prime) gears.

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

Remove Transmission Oil Pan and check for excessive debris.
Remove the Valve Body and air check the UD clutch hydraulic circuit (in the case) per the Service Information.

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

Check the UD bleed orifice, accumulator piston, and accumulator piston seal in the main valve body.

Were there any problems found?

Yes


No

11. EXCESSIVE DEBRIS

Remove the Transmission Oil Pan and check for excessive debris.
Remove the valve body and air check the 4C clutch hydraulic circuit per the Service Information.

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

Check the 4C Accumulator piston for cracks or a cut seal.
Check for a cut or missing #5 check ball.
Check the Solenoid Switch Valve and its plugs for sticking in its bore or excessive wear.

Were there any problems found?

Yes


No

13. CHECK FOR BROKEN REVERSE SUN GEAR WELD

Working through the windows in the bottom of the case, check for a broken Reverse Sun gear weld to the reaction carrier as follows:
(1) Hold the Transmission Output Shaft by holding the Transmission Manual Lever in the park position.
(2) Rotate the Input Annulus gear and drive shell, (the drum that encloses the two rearmost carriers).
(3) Check to see if the reaction carrier (the front most carrier, whose outer shell is splined to the 4C clutch) is rotating faster than the drive shell is being turned.

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

If any other DTCs set during the road test, refer to the appropriate symptom in the Transmission category.
If no other DTC's set during the road test, below is a list of possible causes, but not strictly limited to those:
Check for excessive debris in the Transmission Oil pan, plugged, cracked, or split Primary Transmission Oil Filter and/or seal.
Check for cuts or missing #5 check ball in the main valve body.
Check the 4C and UD accumulator pistons and seals, UD bleed orifice, and the Solenoid Switch Valve and Plugs in the main valve body.
Check the UD clutch piston seals, reaction shaft support seal rings, and the flatness of the pump valve body and pump housing faces.
Check the 4C clutch piston seals, and bleed orifice.
Check the UD clutch piston seals, reaction shaft support seal rings, and dribbler assemblies, and the flatness of the pump valve body and pump housing faces.

View repair

Repair

16. INTERMITTENT DTC

The conditions necessary to set this DTC are not present at this time.
Use the DTC EVENT DATA to help identify the conditions and/or possible causes that may have caused the DTC to set.
Check for any Service Information Tune-ups or Technical Service Bulletins that may apply.

Where there any problems found?

Yes


No