P1752
P1752-TRANSMISSION THROTTLE VALVE SPAN PERFORMANCE
For the Transmission circuit diagram Refer to Transmission Control Systems/Diagram.
For a complete wiring diagram refer to diagrams.
Theory of Operation
The transmission throttle valve cable has been replace by the transmission throttle valve actuator (TTVA). The TTVA consists of an electric DC motor, two potentiometers, and a gear drive system. The TTVA is mechanically connected to the transmission throttle valve in the valve body by the "D" shaped opening in the bottom of the TTVA shaft.
The Transmission Throttle Valve Actuator (TTVA) does not require any mechanical adjustments. All changes in throttle valve position are controlled by the Engine Control Module (ECM).
The TTVA does require an initialization period after the actuator has been removed or replaced. After the actuator has been removed or replaced, move the ignition to the ON position for thirty (30) seconds. This will allow the ECM sufficient time to perform the internal calibration procedures to learn the TTVA's current "zero" position.
- When Monitored:
Ignition on and with or without engine running with transmission in the park or neutral position. Note: Not monitored when either the engine is cranking or while vehicle is moving.
- Set Condition:
Each time the ignition is cycled to the on position, the ECM commands a TTVA internal calibration procedure (autozero) to determine the zero position. After completion of the autozero procedure, the TTVA is instructed to perform a span check to record the minimum and maximum span positions. This DTC will set if the minimum total span is not achieved.
Possible Causes
- TRANSMISSION THROTTLE VALVE ACTUATOR BINDING
- TRANSMISSION THROTTLE VALVE
- INTERNAL TRANSMISSION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
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 5
2. CHECK TTVA FOR SIGNS OF DAMAGE
Turn the ignition off to the lock position.
Visually inspect the TTVA shaft for any signs of external damage or improperly mounted.
NOTE: It is not necessary to remove the TTVA to perform this procedure.
Is the TTVA damaged or improperly mounted?
Yes >>Repair as necessary.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Verification Tests
No >>Go To 3
3. CHECK THE TTVA POSITIONS WITH THE AUTO ZERO FEATURE
NOTE: Each time the ignition is cycled to the on position, the ECM commands a TTVA internal calibration procedure (autozero) to determine the zero position.
With the scan tool, monitor the TTVA position during the autozero test.
Ignition on, engine not running.
After the autozero test is completed, record the position percentage value.
Press and hold the accelerator pedal to full throttle after completion of the autozero test and record.
After completion of the autozero test and recording the autozero value, press and hold the accelerator pedal to full throttle and record the autozero value on the scan tool.
Subtract the TTVA full throttle value from the value recorded after the autozero test.
Is the difference between the two values greater than or equal to 48 degrees?
Yes >>Go To 5
No >>Go To 4
4. CHECK THE TRANSMISSION THROTTLE VALVE
Turn the ignition off to the lock position.
Remove the TTVA from the transmission per the Service Information.
Properly support the TTVA and reconnect the TTVA wiring harness.
Like in the previous step, with the scan tool, monitor the TTVA position during the autozero test.
Ignition on, engine not running.
After the autozero test is completed, record the position percentage value.
Press and hold the accelerator pedal to full throttle after completion of the autozero test and record.
After completion of the autozero test and recording the autozero value, press and hold the accelerator pedal to full throttle and record the autozero value on the scan tool.
Subtract the TTVA full throttle value from the value recorded after the autozero test.
Is the difference between the two values greater than or equal to 48 degrees?
Yes >>Repair internal transmission as necessary. Refer to the Service Information for proper repair procedures for components related to the Transmission Throttle Valve.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Verification Tests
No >>Replace the TTVA per the Service Information.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Verification Tests
5. INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
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). Verification Tests
No >>Test Complete.