P1776
P1776-SOLENOID SWITCH VALVE LATCHED IN LR POSITION
For a complete wiring diagram, refer to: Electrical Diagrams
When Monitored
Every 7 ms when doing PEMCC or FEMCC.
Set Condition
Must be in partial or full EMCC. The DTC is set if LR pressure is detected high for the fourth time.
Possible Causes
- RELATED DTC P0841 PRESENT
- (T16) TRANSMISSION CONTROL RELAY OUTPUT CIRCUIT OPEN
- (T50) L/R PRESSURE SWITCH SENSE CIRCUIT OPEN
- (T50) L/R PRESSURE SWITCH SENSE CIRCUIT SHORT TO GROUND
- (T50) L/R PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE
- INTERNAL TRANSMISSION
- POWERTRAIN CONTROL MODULE
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. 42RLE Automatic Transmission
Theory of Operation
The Solenoid Switch Valve, an internal, hydraulically operated valve, controls the direction of the transmission fluid when the LR solenoid is energized. When the solenoid switch valve is in the downshifted position and the LR solenoid is energized, fluid is directed to the LR element for 1st gear. When the solenoid switch valve is In the upshifted position (2nd, 3rd, and 4th gear) and the LR solenoid is energized, fluid is directed into the Lockup Switch Valve which controls the Torque Converter Clutch. When doing PEMCC or FEMCC, the LR pressure switch should indicate no pressure if the solenoid switch valve is in the LU position. If the LR pressure switch indicates pressure for some time while in partial or full EMCC, the EMCC operation is aborted and momentarily inhibited to avoid accidental application of the LR clutch. EMCC is attempted again when there is no LR pressure. The fourth detection of LR pressure while in PEMCC or FEMCC will result in setting the DTC. Torque converter EMCC operation inhibited. MIL on after 5 minutes of substituted operation.
Diagnostic Test
1. DETERMINING IF RELATED DTC'S ARE PRESENT
With the scan tool, check for other Transmission DTC's
Is the DTC P0841 present also?
Yes >> Refer to the Transmission category and perform the appropriate diagnostic procedure.
Perform 42RLE TRANSMISSION VERIFICATION TEST - Ver 1. Verification Tests.
No >> Go To 2
2. CHECK TO SEE IF DTC P1776 IS CURRENT
With the scan tool, check the STARTS SINCE SET counter for P1776.
NOTE: This counter only applies to the last DTC set.
Is the STARTS SINCE SET counter 2 or less?
Yes >> Go To 3
No >> Go To 10
3. PCM AND WIRING
Turn the ignition off to the lock position.
Remove the Starter Relay.
CAUTION: Removal of the Starter Relay is to prevent a Transmission, NO RESPONSE, condition and disable the starter.
Install the Transmission Simulator, Miller tool #8333 and the Electronic Transmission Adapter kit 8333-1A.
Ignition on, engine not running.
With the Transmission Simulator, turn the Pressure Switch selector switch to L/R.
With the scan tool, monitor the L/R Pressure Switch State while pressing the Pressure Switch Test button.
Did the Pressure Switch state change from open to closed when the test button was pressed?
Yes >> Go To 4
No >> Go To 5
4. INTERNAL TRANSMISSION
If there are no possible causes remaining, view repair.
Repair
Repair internal transmission as necessary per the Service Information. Inspect the Solenoid Switch Valve per the Service Information and repair or replace as necessary. If no problems are found, replace the Transmission Solenoid/Pressure Switch Assembly.
Perform 42RLE TRANSMISSION VERIFICATION TEST - Ver 1. Verification Tests.
5. (T16) TRANSMISSION CONTROL RELAY OUTPUT CIRCUIT OPEN
Turn the ignition off to the lock position.
Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.
Remove the Transmission Control Relay.
Connect a jumper wire between the (A104) Fused B+ circuit and the (T16) Transmission Control Relay Output circuit.
NOTE: Check connectors - Clean/repair as necessary.
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.
Disconnect the PCM C4 harness connector. Remove the Starter Relay.
Using a 12-volt test light connected to ground, check all (T16) Transmission Control Relay Output circuits in the appropriate terminals of special tool #8815.
NOTE: The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.
Does the test light illuminate brightly on all Transmission Control Relay Output circuits?
Yes >> Repair the (T16) Transmission Control Relay Output circuit(s) for an open.
Perform 42RLE TRANSMISSION VERIFICATION TEST -Ver 1. Verification Tests.
No >> Go To 6
6. (T50) L/R PRESSURE SWITCH SENSE CIRCUIT OPEN
Turn the ignition off to the lock position.
Disconnect the PCM C4 harness connector.
Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance of the (T50) L/R Pressure Switch Sense circuit from the appropriate terminal of special tool #8815 to the Transmission Solenoid/Pressure Switch Assembly harness connector.
Is the resistance above 5.0 ohms?
Yes >> Repair the (T50) L/R Pressure Switch Sense circuit for an open.
Perform 42RLE TRANSMISSION VERIFICATION TEST - Ver 1. Verification Tests.
No >> Go To 7
7. (T50) L/R PRESSURE SWITCH SENSE CIRCUIT SHORT TO GROUND
Turn the ignition off to the lock position.
Disconnect the PCM C4 harness connector.
Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between ground and the (T50) L/R Pressure Switch Sense circuit.
Is the resistance below 5.0 ohms?
Yes >> Repair the (T50) L/R Pressure Switch Sense circuit for a short to ground.
Perform 42RLE TRANSMISSION VERIFICATION TEST - Ver 1. Verification Tests.
No >> Go To 8
8. (T50) L/R PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE
Turn the ignition off to the lock position.
Disconnect the PCM C4 harness connector.
Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.
Remove the Transmission Control Relay
NOTE: Check connectors - Clean/repair as necessary.
Connect a jumper wire between the (Internal) Fused B+ circuit and (T16) Transmission Control Relay Output circuit in the Transmission Control Relay connector.
Ignition on, engine not running.
Measure the voltage of the (T50) L/R Pressure Switch Sense circuit.
Is the voltage above 0.5 volts?
Yes >> Repair the (T50) L/R Pressure Switch Sense circuit for a short to voltage.
Perform 42RLE TRANSMISSION VERIFICATION TEST - Ver 1. Verification Tests.
No >> Go To 9
9. POWERTRAIN CONTROL MODULE
Using the schematics as a guide, inspect the wiring and connectors. Repair as necessary Pay particular attention to all power and ground circuits.
If there are no possible causes remaining, view repair.
Repair
Replace the Powertrain Control Module per the Service Information. With the scan tool perform QUICK LEARN, then program Pinion Factor in the Front Control Module.
Perform 42RLE TRANSMISSION VERIFICATION TEST - Ver 1. Verification Tests.
10. INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
Test drive and verify if the transmission is launching in 2nd gear and/or no TCC engagement.
With the scan tool, check the EATX DTC EVENT DATA to help identify the conditions in which the DTC was set.
Are there 2nd gear launches and/or no TCC engagement?
Yes >> Disassemble and inspect the Valve Body per the Service Information and repair or replace as necessary. If no problems are found in the Valve Body, replace the Transmission Solenoid Pressure Switch Assembly.
Perform 42RLE TRANSMISSION VERIFICATION TEST - Ver 1. Verification Tests.
No >> Test Complete.