P1750

P1750-TRANSMISSION THROTTLE VALVE POSITION SENSOR CIRCUIT HIGH





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:

When the Engine Control Module (ECM) detects the monitored Transmission Throttle Valve Position Sensor voltage rises above a predetermined value.







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 7



2. CHECK THE TTVA

With the scan tool, record and erase Engine DTCs.

Turn the ignition off to the lock position.

Disconnect the TTVA harness connector.

Ignition on, engine not running.

With the scan tool, read Engine DTCs.

Did the DTC Transmission Throttle Valve Position Sensor Circuit High set?

Yes

- Go To 4

No

- Go To 3



3. CHECK THE (K900) SENSOR GROUND CIRCUIT FOR AN OPEN





Ignition on, engine not running.

With the scan tool, record and erase Engine DTCs.

Turn the ignition off to the lock position.

Disconnect the TTVA harness connector.


NOTE: Check connectors - Clean/repair as necessary.

Connect a jumper wire between the (K900) Sensor Ground circuit and the (F856) 5-volt Supply circuit in the TTVA harness connector.

Ignition on, engine not running.

With the scan tool, read Engine DTCs.

Did either P0642 or P0652 Sensor Supply Voltage DTC set?

Yes

- Replace the TTVA.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test

No

- Repair the (K900) TTVA Sensor Ground circuit for an open.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test



4. CHECK THE (K312) TTVA POSITION SENSOR SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE





Turn the ignition off to the lock position.

Disconnect the ECM C1 and C2 harness connectors.

Ignition on, engine not running.

Measure the voltage of the (K312) TTVA Position Sensor Signal circuit.

Is the voltage above 0.5 volts?

Yes

- Repair the (K312) TTVA Position Sensor Signal circuit for a short to voltage.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test

No

- Go To 5



5. CHECK THE (K312) TTVA POSITION SENSOR SIGNAL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT





Measure the resistance between the (K312) TTVA Position Sensor Signal circuit and all other circuits in the ECM C1 and C2 harness connectors.

Is the resistance below 100 kohms between the (K312) TTVA Position Sensor Signal circuit and any other circuit(s) in the ECM C1 or C2 harness connectors.

Yes

- Repair the (K312) TTVA Position Sensor Signal circuit for a short to another circuit(s).
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test

No

- Go To 6



6. CHECK THE ECM OPERATION

Turn the ignition off to the lock position.

Reconnect all previously disconnected connectors.

Ignition on, engine not running.

With the scan tool, record and erase Engine DTCs.

Turn the ignition off to the lock position.

Disconnect the TTVA harness connector.

Ignition on, engine not running.

With the scan tool, read Engine DTCs.

Did the DTC Transmission Throttle Valve Position Sensor Circuit High set?

Yes

- 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

No

- Go To 7



7. INTERMITTENT WIRING AND CONNECTORS

The conditions necessary set this DTC are not present at this time.

Use the Freeze Frame Data to help duplicate the conditions that set the DTC. Pay particular attention to the DTC set conditions, such as, VSS, MAP, ECT, and Load.

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.

Refer to any 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.