DTC P0783: 3-4 SHIFT SOLENOID, NO RPM DROP @ 3-4 SHIFT
Circuit Description
Circuit is monitored continuously while ignition is on and engine is running. DTC sets if expected RPM drop does not occur within 4 seconds of requested gear change by PCM. Test must fail 3 times to set DTC.
Possible Cause
The following items may be area of concern:
- Transmission mechanically defective.
- TP sensor DTCs set.
- Transmission 3-4 shift solenoid wiring harness defective.
- Transmission fluid burnt or oil pan contains excessive debris.
Diagnostic Procedure
1. Using scan tool, read DTCs. If good trip counter for DTC P0783 is not displayed or displayed count is not zero, go to step 7 . If good trip counter is displayed and displayed count is zero, go to next step.
2. If any listed DTCs are present, perform appropriate diagnostic test(s). See 3-4 SHIFT SOLENOID TESTS table. If no DTCs are present, go to next step.
3. Check transmission fluid for proper level and for any debris. Fill or repair transmission as necessary. See appropriate SERVICING article in AUTOMATIC TRANSMISSIONS. If fluid level and condition are okay, go to next step.
4. Connect a 0-300 psi (0-21 kg/cm2 ) pressure gauge to transmission OD clutch pressure test port. Connect a second 0-300 psi (0-21 kg/cm2 ) pressure gauge to transmission governor pressure test port. See HYDRAULIC PRESSURE TESTS . Ensure engine and transmission are at normal operating temperature. With an assistant, test drive vehicle. Using scan tool, select GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select 4th gear while monitoring pressure gauge. Governor pressure should increase to greater than 20 psi (1.4 kg/cm2 ) and OD pressure should increase to greater than 40 psi (2.8 kg/cm2 ). If pressures are as specified, go to next step. If pressures are not as specified, go to step 6 .
5. Ensure ignition is off. Drain transmission fluid and remove oil pan. Inspect pan for debris and burnt fluid. Repair as needed. See appropriate OVERHAUL article. If condition of fluid is acceptable and excessive debris in oil pan is not found, go to next step.
6. Leave gauges connected. Replace 3-4 shift solenoid. See REMOVAL & INSTALLATION in appropriate SERVICING article in AUTOMATIC TRANSMISSIONS. Install transmission oil pan and fill with fluid. Start engine and allow engine and transmission to reach normal operating temperature. Using scan tool, select GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select 4th gear while monitoring pressure gauges. Governor pressure should increase to greater than 20 psi (1.4 kg/cm2 ) and OD pressure should increase to greater than 40 psi (2.8 kg/cm2 ). If pressures are as specified, no problem is currently present. Testing is complete. If pressures are not as specified, internal transmission malfunction exists. Repair as necessary, paying attention to seals and clutches related to OD clutch.
7. Conditions required to set DTC are not currently present. Inspect all applicable connectors and terminals for damage. Repair as necessary. If connectors and terminals are okay, see INACTIVE DTC CONDITION under SELF-DIAGNOSTIC SYSTEM. Testing is complete.