What Does P0789 Mean?
The TCM has detected a malfunction in the Shift/Timing Solenoid circuit, which on some platforms corresponds to the 3-2 Shift Solenoid electrical circuit. This code indicates an electrical problem with the solenoid that controls either shift timing or the specific 3rd-to-2nd gear downshift. The circuit may have an open, short, or out-of-range resistance that prevents proper solenoid operation.
Common Causes
35%
Failed shift/timing solenoid (internal coil open or short circuit)
25%
Damaged wiring between TCM and transmission connector
20%
Corroded or damaged transmission connector
12%
TCM solenoid driver circuit failure
8%
Poor ground connection affecting the solenoid circuit
Diagnostic Steps
1
Identify which solenoid this code refers to on the specific vehicle — it may be a timing solenoid or the 3-2 shift solenoid depending on the platform.
2
Measure the solenoid resistance at the transmission connector and compare to manufacturer specification.
3
Inspect the transmission external connector for water intrusion, corrosion, bent pins, or pushed-back terminals.
4
Check for proper voltage and ground at the solenoid connector when commanded by the TCM.
5
Perform a wiggle test on the wiring harness while monitoring the solenoid circuit for intermittent connection issues.
6
If external tests pass, remove and bench-test the solenoid to confirm internal failure.
Estimated Repair Cost
$150 - $1,000
Parts + labor, varies by vehicle and location
The TCM has detected a malfunction in the Shift/Timing Solenoid circuit, which on some platforms corresponds to the 3-2 Shift Solenoid electrical circuit. This code indicates an electrical problem with the solenoid that controls either shift timing or the specific 3rd-to-2nd gear downshift. The circ...
The most common cause of P0789 (Shift/Timing Solenoid Malfunction/ 3-2 Shift Solenoid Circuit Electrical) is: Failed shift/timing solenoid (internal coil open or short circuit)
Typical repair costs for P0789 range from $150 to $1,000, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle may have harsh or absent 3-2 downshifts, or generally poor shift timing. Limp mode is possible. The vehicle is drivable at reduced capability but should be repaired promptly to restore proper shift control and prevent additional wear.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0789 to identify the root cause.
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Quick Info
Category
Powertrain
System
Automatic Transmission
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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