What this code means
P0974 may indicate an open-type electrical fault in the shift solenoid valve A control circuit.
What the vehicle may do
- The vehicle may have automatic transmission shift complaints.
- The code may set with limited obvious drivability symptoms.
- The transmission control strategy may react differently depending on when the fault is detected.
Possible fault areas
- Possible shift solenoid valve A circuit issue.
- Possible shift solenoid wire harness issue.
- Possible connector or terminal concern between the solenoid circuit and the PCM.
- Possible PCM-side control issue.
Diagnostic path
Opening context
On this 2010-2015 Honda Civic with the 1.8 gas engine, P0974 is pointing at the shift solenoid valve A electrical circuit, specifically an open-type fault. The car may have shift complaints or may set the code without a major drivability change, but the diagnostic path treats this as an electrical circuit problem. Broadly, we may be dealing with the solenoid circuit, the shift solenoid wire harness, connector or terminal issues, or the PCM side of the circuit. Before getting into the checks, save the captured data and any on-board snapshot with the HDS, and start with the basic system checks. Also keep this important point in mind: this code is caused by an electrical circuit problem and cannot be caused by a mechanical problem in the transmission.
Duplicate the fault first
Start by turning the ignition switch to ON (II), clearing the DTC with the HDS, then starting the engine with the shift lever in P. Wait for at least 1 second, then check for Pending or Confirmed DTCs with the HDS. If P0974 comes right back, the failure is duplicated and you move into the circuit checks. If it does not come back, command shift solenoid valve A from the Miscellaneous Test Menu with the HDS. If you hear the solenoid click, the solenoid operation check passes for the moment, so continue by starting the engine in P again, waiting for at least 1 second, and watching the OBD STATUS for P0974. If the HDS shows FAILED, the fault is duplicated. If it shows PASSED, treat it as an intermittent at this time and look closely for poor connections or loose terminals between shift solenoid valve A and the PCM. If it shows NOT COMPLETED, run the operating condition again instead of making a call too early.
Check the solenoid circuit resistance
Once the fault is duplicated, turn the ignition switch to LOCK (0), jump the SCS line with the HDS, and disconnect PCM connector B (49P). Measure resistance on the SH_A circuit between PCM connector B (49P) No. 21 (BLU) and body ground. The expected result is 13.8－17.1 Ω. If the resistance is in that range, shift solenoid valve A is OK by this check. At that point, update the PCM if it does not have the latest software, or substitute a known-good PCM, then go to repair verification. If the resistance is not 13.8－17.1 Ω, continue down the circuit and check for an open.
Check the SH_A wire for an open
Next, disconnect the shift solenoid wire harness 8P connector. With the ignition still at LOCK (0), the shift solenoid wire harness 8P connector disconnected, and PCM connector B (49P) disconnected, check continuity on the SH_A wire between shift solenoid wire harness 8P connector No. 8 (BLU) and PCM connector B (49P) No. 21 (BLU). If you have continuity, that section of the SH_A wire is OK and you keep moving toward the solenoid harness. If you do not have continuity, repair the open in the SH_A wire between the shift solenoid wire harness and the PCM, then verify the repair.
Check the shift solenoid wire harness
If the SH_A wire to the PCM checks good, remove the shift solenoid wire harness and check continuity through the harness. The test is between shift solenoid wire harness 7P connector No. 7 (BLU) and shift solenoid valve A 1P connector No. 1 (BLU), with the 7P connector, the solenoid 1P connector, and PCM connector B (49P) disconnected. If there is continuity, the shift solenoid wire harness is OK, so replace shift solenoid valve A and then verify the repair. If there is no continuity, replace the shift solenoid wire harness and then verify the repair.
Verify the repair
Keep verification separate from the testing. Reconnect all connectors, turn the ignition switch to ON (II), clear the DTC with the HDS, then start the engine with the shift lever in P and wait for at least 1 second. After that, test-drive the vehicle in 2nd gear for at least 1 second, and monitor the OBD STATUS for P0974 with the HDS. If it shows PASSED, troubleshooting is complete. If a known-good PCM was substituted, replace the original PCM. Afterward, check for any other Pending or Confirmed DTCs and handle those by what they indicate. If P0974 shows FAILED, go back to the beginning and recheck the path; if the PCM was updated, substitute a known-good PCM and check OBD STATUS again. If the status is NOT COMPLETED, meet the test condition and check OBD STATUS again.
Takeaway and CTA
The takeaway on P0974 is simple: prove whether the code is current, then work the electrical path in order—solenoid response, resistance, SH_A continuity, and the shift solenoid harness—before making the final call. For more diagnostic training, visit stepdiagnostics.com.
Final check
P0974 is approached as an electrical circuit diagnosis, not a mechanical transmission diagnosis.
For more guided automotive diagnostics, visit STEP Diagnostics.
