P1736
P1736-GEAR RATIO ERROR IN 2ND PRIME
For a complete wiring diagram, refer to the Wiring Information.
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:
NOTE: Various Gear Ratio Error DTCs will set only if the transmission slips after first achieving the correct ratio. Therefore, a transmission with no drive (or reverse) may not set any Gear Ratio Error DTC because it never achieves a correct gear ratio.
1) Once in a particular gear, if the gear ratio varies from the correct 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 which 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 pulses from the input speed sensor when at a stop 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 Monitored:
Continuously with the ignition on, engine running, and after the transmission has achieved the proper gear ratio.
- 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
Always perform the the 545RFE Pre-Diagnostic Troubleshooting Procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
1. CHECK IF RELATED DTCS ARE PRESENT
1. With the scan tool, read DTCs.
Are any Transmission solenoid, line pressure, speed sensor, or loss of prime DTCs present?
Yes
- Perform the appropriate diagnostic procedure. Perform the test for P0944-LOSS OF PRIME first if it is present. P0944
No
- Go To 2
2. CHECK THE EVENT DATA
1. With the scan tool, read and record the Event Data.
NOTE: Make sure to record all Event Data stored in the scan tool for future reference in this test procedure.
Does the Event Data display information for the DTC P1736?
Yes
- Go To 3
No
- Go To 6
3. CHECK INPUT RPM IN THE EVENT DATA
In the Event Data recorded earlier, does the Input rpm read zero?
Yes
- Check the input speed sensor and wiring. Perform test P0716 and diagnose as if the DTC is current. P0716
No
- Go To 4
4. CHECK LINE PRESSURE READING
In the Event Data recorded earlier, 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
1. Turn the ignition off to the lock position.
2. Remove and inspect the Transmission Oil Pan for excessive debris.
3. Remove and inspect the Primary 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
- Repair the plugged, cracked, or split Primary Transmission Oil Filter and/or seal. If the Primary Transmission Oil Filter is plugged, refer to the Service Information for the proper hydraulic clutch repair procedure. Removal.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
No
- Remove the Transmission Oil Pump. Check the main Regulator Valve for sticking in its bore, scoring, and/or damage and clean and repair as necessary. If no problem is found, replace the Transmission Solenoid/TRS Assembly. Transmission Solenoid and TRS Assembly - Removal.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
6. CHECK IF THE DTC P1736 IS CURRENT
1. With the scan tool, perform the 2nd Prime Gear Clutch Test. Follow the instructions on the scan tool.
2. Increase the throttle angle, TPS Degree, to 30° 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
- Go To 7
No
- Go To 9
7. CHECK FOR INTERMITTENT OPERATION
1. Check the Shifter adjustment.
2. Intermittent gear ratio DTCs can be set by problems in the Input and Output Speed Sensor circuits and/or Speed Sensor Ground circuit.
3. Check the Speed Sensor wiring and connectors for good connection, then perform a wiggle test using the Transmission Simulator 8333A.
Were there any problems found?
Yes
- Repair as necessary.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
No
- Go To 8
8. CHECK FOR SLIPPAGE
1. With the scan tool, erase Transmission DTCs.
2. Road test the vehicle.
3. 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
- Go To 11
No
- Go To 14
9. UD CLUTCH HYDRAULIC CIRCUIT
1. Remove Transmission Oil Pan and check for excessive debris.
2. Remove the Valve Body and air check the UD clutch hydraulic circuit (in the case).
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
- Repair as necessary. Check the UD clutch piston seals and the dribbler assembly, reaction shaft support seal rings, and the flatness of the pump valve body and pump housing faces. Check main regulator valve for sticking in the bore.
NOTE: If the UD clutch has failed but no obvious cause is found (such as a cut piston seal, broken seal ring, stuck regulator valve or any other items listed above) replace the Transmission Solenoid/TRS Assembly in addition to any necessary internal repairs. Transmission Solenoid and TRS Assembly - Removal .
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
No
- Go To 10
10. UD ACCUMULATOR PISTON
1. Check the UD bleed orifice, accumulator piston, and accumulator piston seal in the main valve body.
Were there any problems found?
Yes
- Repair as necessary. Refer to the Service Information for proper repair procedures. Valve Body - Removal.
No
- Replace the Transmission Solenoid/TRS Assembly. Transmission Solenoid and TRS Assembly - Removal.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
11. EXCESSIVE DEBRIS
1. Remove the Transmission Oil Pan and check for excessive debris.
2. Remove the valve body and air check the 4C clutch hydraulic circuit.
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
- Repair as necessary. Refer to the Service Information for proper repair procedures. Note: Check the 4C piston seals and bleed orifice.
NOTE: If the 4C clutch has failed but no obvious cause is found (such as a cut piston seal, broken seal ring, stuck regulator valve or any other items listed above) replace the Transmission Solenoid/TRS Assembly in addition to any necessary internal repairs.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
No
- Go To 12
12. 4C ACCUMULATOR
1. Check the 4C Accumulator piston for cracks or a cut seal.
2. Check for a cut or missing No. 5 check ball.
3. Check the Solenoid Switch Valve and its plugs for sticking in its bore or excessive wear.
Were there any problems found?
Yes
- Repair as necessary. Refer to the Service Information for proper repair procedures. Valve Body - Removal.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
No
- Go To 13
13. CHECK FOR BROKEN REVERSE SUN GEAR WELD
1. Working through the windows in the bottom of the case, check for a broken Reverse Sun gear weld to the reaction carrier as follows:
- Hold the Transmission Output Shaft by holding the Transmission Manual Lever in the park position.
- Rotate the Input Annulus gear and drive shell, (the drum that encloses the two rearmost carriers).
- 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
- Replace the Transmission Solenoid/TRS Assembly. Transmission Solenoid and TRS Assembly - Removal.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
No
- Replace the reaction carrier. Removal.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
14. CHECK IF THE DTC RESET
Did the DTC P1736 reset during the road test?
Yes
- Go To 15
No
- Go To 16
15. LIST OF POSSIBLE CAUSES
1. If any other DTCs set during the road test, refer to the appropriate test in the Transmission category.
2. If no other DTCs 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 No. 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.
Repair
- Repair as necessary. Refer to the Service Information for proper repair procedures. Removal.
NOTE: If the UD or 4C clutch has failed but no obvious cause is found (such as a cut piston seal, broken seal ring, stuck regulator valve or any other items listed above) replace the Transmission Solenoid/TRS Assembly in addition to any necessary internal repairs.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
16. INTERMITTENT DTC
1. The conditions necessary to set this DTC are not present at this time.
2. Use the Event Data to help identify the conditions and/or possible causes that may have caused the DTC to set.
3. Check for any Service Information Tune-ups or Technical Service Bulletins that may apply.
Where there any problems found?
Yes
- Repair as necessary.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
No
- Test Complete.