Mechanics

CODE P0740 TORQUE CONVETER CLUTCH SOLENOI

1999 Honda Accord

Transmission problem
1999 Honda Accord 6 cyl Front Wheel Drive Automatic 170000 miles

Hi!

I have question related to the transmission. The car start slip gear when I shift to D4 or 1, 2 or D3, the RPM jump to 2000 but the car doesn't move much. The CEL on and I pulled out the code P0740. I right away changed the transmission fluid, unussually in the old transmission has a lot of metal deris. I also troublshoot and clean Lockup Control Solenoid Valve Shift Control Solenoid Valve A and A/T cluth Pressure Control solenoid Valve A/B. All of two unit above pass the Ohm test within the range and click sound heard when test. Also no futher code fail for the 2nd, 3rd clutch pressure switch. The car run fine after I changed Transmission fluid but the unfortunatelly, the CEL still on with code P0740. The RPM also some time jump little on low speed 10 or 20 MPH or when I stop on the red light or Stop. Please let me know what wrong cause for the code P0740? Is the Torque converter failed or the whole transmission dead? The car run fine but still had error code P0740 and RPM will jump when slow speed.
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Lovehonda
November 22, 2009.




Hi lovehonda,

Here are the diagnostic procedures for the trouble code.

DTC P0740/40: LOCK - UP CONTROL SYSTEM

NOTE: DO NOT perform this DTC test until all other DTCs have been repaired first.

1. Using scan tool, retrieve A/T freeze data. Clear fault codes and road test vehicle under same conditions freeze data was recorded. If fault code returns, go to next step. If fault code does not return, problem is intermittent, check transaxle and PCM connections.
2. Using scan tool, check for any other DTCs. If any other DTCs are present, repair those DTCs first, then recheck for DTC P0740/40. If no other DTCs are present, go to next step.

3. Test line pressure. If line pressure is within specification, go to next step. If line pressure is not within specification, repair hydraulic system as necessary.

4. Test clutch pressure. If clutch pressure is within specification, go to next step. If clutch pressure is not within specification, repair hydraulic system as necessary.

5. Replace lock-up control solenoid valve/shift control solenoid valve " A" assembly. Turn ignition off and clear codes. Road test vehicle at over 50 MPH for more than one minute. Recheck DTCs. If P0740/40 returns, go to next step. If P0740/40 does not return, system is okay.

6. Replace A/T clutch pressure control solenoid assembly. Turn ignition off and clear codes. Road test vehicle at over 50 MPH for more than one minute. Recheck DTCs. If P0740/40 returns, go to next step. If P0740/40 does not return, system is okay.

7. Replace torque converter. Turn ignition off and clear codes. Road test vehicle at over 55 MPH for more than one minute. Recheck DTCs. If P0740/40 returns, replace transaxle and torque converter. If P0740/40 does not return, system is okay.

KHLow2008
Nov 27, 2009.
Hi KHlow2008,

Thanks for take your time reply the question. I did find down it cause P0740, the werd thing that unit ( Shift Control Solenoid Valve A) I had been test the Ohm within the range or 12-25 Ohm also I hook up Terminal 1 to Positive battery and I heard the clicking sound. A week later after I change Transmission oil again, test the unit and it fail the Ohm so I am replacing that unit let see if it work or not. Thanks for the information and maybe someone will need it.
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Tiny
Lovehonda
Nov 27, 2009.
You are welcomed. However this is a rather common problem and in most cases the trans needs to be replaced.

KHLow2008
Nov 27, 2009.

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