P1755
P1755-TRANSMISSION THROTTLE VALVE CONTROL CIRCUIT
For a complete wiring diagram refer to Diagrams/Electrical. Electrical 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:
Continuously with the ignition on.
- Set Condition:
The current detected on the TTVA circuit is greater than a threshold for a calibrated amount of time or the feedback to the controller does not match the intended state.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Checkout (Diesel)
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 12
2. CHECK THE TTVA
Turn the ignition off to the lock position.
Disconnect the TTVA harness connector
Connect a 12-volt test light between the (K314) TTVA Motor (+) circuit and the (K315) TTVA Motor (-) circuit in the TTVA harness connector.
Monitor the test light in the following step.
NOTE: The test light should momentarily flash brightly, one time, immediately after the ignition is turned to the on position.
Ignition on, engine not running.
Did the test light illuminate brightly one time after turning the ignition to the on position?
Yes
- Go To 3
No
- Go To 4
3. CHECK THE (K315) TTVA MOTOR (-) CIRCUIT FOR A SHORT TO GROUND
Turn the ignition off to the lock position.
Disconnect the ECM C1 harness connector.
Measure the resistance between ground and the (K315) TTVA Motor (-) circuit.
Is the resistance below 5.0 ohms?
Yes
- Repair the (K315) TTVA Motor (-) circuit for a short to ground.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test
No
- Check the Transmission Throttle Valve components for proper movement or sticking. If no problems are found replace the TTVA.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test
4. CHECK THE (K314) TTVA MOTOR (+) CIRCUIT FOR AN OPEN
Turn the ignition off to the lock position.
Disconnect the ECM C1 and C2 harness connectors.
Measure the resistance of the (K314) TTVA Motor (+) circuit between the ECM C1 harness connector and the TTVA harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go To 5
No
- Repair the (K314) TTVA Motor (+) circuit for an open.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test
5. CHECK THE (K315) TTVA MOTOR (-) CIRCUIT FOR AN OPEN
Measure the resistance of the (K315) TTVA Motor (-) circuit between the ECM C1 harness connector and the TTVA harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go To 6
No
- Repair the (K315) TTVA Motor (-) circuit for an open.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test
6. CHECK THE (K314) TTVA MOTOR (+) CIRCUIT FOR A SHORT TO GROUND
Measure the resistance between ground and the (K314) TTVA Motor (+) circuit.
Is the resistance below 5.0 ohms?
Yes
- Repair the (K314) TTVA Motor (+) circuit for a short to ground.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test
No
- Go To 7
7. CHECK THE (K314) TTVA MOTOR (+) CIRCUIT FOR A SHORT TO VOLTAGE
Ignition on, engine not running.
Measure the voltage of the (K314) TTVA Motor (+) circuit.
Is the voltage above 0.5 volts?
Yes
- Repair the (K314) TTVA Motor (+) circuit for a short to voltage.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test
No
- Go To 8
8. CHECK THE (K315) TTVA MOTOR (-) CIRCUIT FOR A SHORT TO VOLTAGE
Measure the voltage of the (K315) TTVA Motor (-) circuit.
Is the voltage above 0.5 volts?
Yes
- Repair the (K315) TTVA Motor (-) circuit for a short to voltage.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test
No
- Go To 9
9. CHECK THE (K314) TTVA MOTOR (+) CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT
Turn the ignition off to the lock position.
Measure the resistance between the (K314) TTVA Motor (+) circuit and every other circuit in the ECM C1 and C2 harness connectors.
Is the resistance below 5.0 ohms between the (K314) TTVA Motor (+) circuit and any other circuit in the ECM C1 and C2 harness connectors?
Yes
- Repair the (K314) TTVA Motor (+) for a short to another circuit(s).
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test
No
- Go To 10
10. CHECK THE (K315) TTVA MOTOR (-) CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT
Measure the resistance between the (K315) TTVA Motor (-) circuit and every other circuit in the ECM C1 and C2 harness connectors.
Is the resistance below 5.0 ohms between the (K315) TTVA Motor (-) circuit and any other circuit in the ECM C1 and C2 harness connectors?
Yes
- Repair the (K315) TTVA Motor (-) for a short to another circuit(s).
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test
No
- Go To 11
11. CHECK THE ECM OPERATION
Turn the ignition off to the lock position.
Reconnect all previously disconnected connectors.
Turn the ignition on for the period of 30 seconds to allow the ECM to reset.
Turn the ignition off to the lock position.
Disconnect the TTVA harness connector.
Connect a 12-volt test light between the (K314) TTVA Motor (+) circuit and the (K315) TTVA Motor (-) circuit in the TTVA harness connector.
Monitor the test light in the following step.
NOTE: The test light should momentarily flash brightly, one time, immediately after the ignition is turned to the on position.
Ignition on, engine not running.
Did the test light illuminate brightly one time after turning the ignition to the on position?
Yes
- Go To 12
No
- Using the schematics as a guide, check the Engine Control Module (ECM) pins, terminals, and connectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace and program the ECM.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test
12. INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
Use the Freeze Frame Data to help duplicate the conditions in which the DTC originally set. Pay particular attention to the DTC set conditions, such as, VSS, MAP, ECT, and Load
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). Transmission Verification Test
No
- Test Complete.