Technical Definition:

4 – 5 Shift

Trouble Code: P0784
Address: 0x0784
System: Powertrain
Subsystem: Transmission Controls
Technical Description:

On vehicles with electronically controlled automatic transmissions, the 4-5 shift solenoid is responsible for actuating the hydraulic circuits to activate clutches or bands that change gears inside the automatic transmission. The shift solenoids are controlled by either a Transmission Control Module (TCM), or the Engine Control Unit / Powertrain Control Module (ECU / PCM). The control circuit may be power or ground side controlled depending on the application.

Possible Causes:
  • 4-5 shift solenoid failure
  • Electrical short to power – pinched wires
  • Electrical short to ground – pinched wires
  • Open in power or ground circuit wiring – disconnected or loose connections
  • TCM or PCM internal failure

Possible Symptoms:
  • Check engine light illuminated (Malfunction Indicator Lamp / MIL)
  • Vehicle will not shift from 4th to 5th gear

4-5 Shift Malfunction

Possible Solutions:
  • Disconnect PCM or TCM wiring harness, depending on the application and using an electrical diagram as reference, check for excessive resistance or an open in the control circuit. Using a Digital Volt Ohm Meter (DVOM) set to the Ohms scale, check for resistance on the 4-5 solenoid power and ground sources to determine if there is an open circuit or excessive resistance in the 4-5 solenoid. Visually inspect for for any pinched, disconnected or loose wires on the harness connectors.
  • Short to power: Disconnect battery positive cable and wiring harness connector at transmission and check for continuity using the DVOM between power source and solenoid circuit wiring in key on / engine off (KOEO) position as well as the key off position.
  • Short to ground: Disconnect battery positive cable and wiring harness connector at transmission and check for continuity using the DVOM between 4-5 solenoid power source and a known good ground.
  • TCM or PCM failure: Using an advanced scan tool capable of controlling solenoids, manually activate the 4-5 shift solenoid. It may be necessary to manually activate transmission control relay on some vehicles if power is not present at the transmission wiring harness connector. If a scan tool is not available, it will be necessary to monitor the 4-5 solenoid circuit to determine if the TCM or PCM is sending a power or ground signal to the 4-5 solenoid during vehicle operation.

OBD-II Trouble Code Type:

Diagnostic Step:

Tech Notes:

– Low transmission fluid level
– Dirty transmission fluid
– Faulty shifting solenoid valve
– Shifting solenoid valve harness is open or shorted
– Shifting solenoid valve circuit poor electrical connection

Specific Makes:

– Transmission may not shift to the next gear

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