DTC P0734

DTC P0734: 4th Gear Incorrect Ratio

General Description

Courtesy of HONDA, U.S.A., INC.

Courtesy of HONDA, U.S.A., INC.

To engage 4th gear, line pressure is supplied to the 4th clutch piston, engaging the 4th clutch, and the mainshaft and the mainshaft 4th gear are connected and revolve together. Hydraulic pressure is supplied to the 4th clutch through the ATF strainer → the ATF pump → the regulator valve → the manual valve → the shift valves → the feed pipe → the 4th clutch piston. (A shift valve failure in the supply route above is detected by the malfunction detection of each shift solenoid valve.) The powertrain control module (PCM) computes the ratio of the input shaft (mainshaft) speed to the output shaft (countershaft) speed. When the ratio is not the 4th gear ratio, the PCM detects a malfunction of the hydraulic circuit or the 4th clutch and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status

Execution	Continuous
Sequence	None
Duration	12 seconds or more
DTC Type	Two drive cycles, MIL off, A/T gear position indicator blinks
OBD Status	PASSED/FAILED/NOT COMPLETED (STILL TESTING)

Enable Conditions

Condition	Minimum	Maximum
Engine speed [ENGINE SPEED]	1, 000 RPM	-
Vehicle speed [VEHICLE SPEED]	8 mph (12 km/h)	-
Battery voltage [BATTERY VOLTAGE]	11 V	-
Shift lever position	D
No active DTCs set (prevents monitor from running)	P0117, P0118, P0122, P0123, P0222, P0223, P0705, P0706, P0716, P0717, P0718, P0721, P0722, P0723, P0731, P0732, P0733, P0735, P0747, P0752, P0756, P0757, P0761, P0771, P0776, P0777, P0780, P0796, P0797, P0962, P0963, P0966, P0967, P0970, P0971, P0973, P0974, P0976, P0977, P0979, P0980, P0982, P0983, P0985, P0986, P1658, P1659, P1683, P1684, P1730, P1731, P1732, P1733, P1734, P2101, P2118, P2122, P2123, P2127, P2128, P2135, P2138, P2176

[ ]: HDS Parameter

Malfunction Threshold

The actual gear ratio must match one of these conditions for at least 12 seconds with the 4th gear command:

Actual gear ratio is greater than the 4th gear ratio by a factor of 1.2
Actual gear ratio is less than the 4th gear ratio by a factor of 0.75

Possible Cause

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

Shift control system failure
4th clutch disc surface worn
ATF pump flow pressure insufficient

Confirmation Procedure

With the HDS

None.

With the Driving Pattern

Start the engine.
Drive the vehicle in D at a speed of 8 mph (12 km/h) or more for at least 12 seconds in 4th gear.

Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

Diagnosis Details

Conditions for setting the DTC

When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, a Confirmed DTC and the freeze data are stored. The MIL does not come on.

Conditions for clearing the DTC

The Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.