2001 Civic Transmission Control Module electrical problem

Maintenance/Repairs
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1

Hello, I got a 2001 civic LX automatic transmission. I did replace the transmission on it BUT now there is a check engine light comes on and the code reader says P0740 “Torque converter clutch solenoid circuit/Open” it seems like a an electrical problem. up on the information I got from the internet I have replaced Torque converter clutch solenoid, thermostat, engine coolant temperature sensor and fan temperature sensor on the thermostat body. Still I got the check engine light coming on.

Anyone out there knows exactly what might be wrong?

3

Have you checked the TC clutch solenoid connector? Can you feel the clutch engage and RPMs become steady at a constant speed?

4

If there is no drivability issues with your car,disconnect the battery for a couple of hours or overnight.to clear the CEL.

5

Before you disconnect the battery on your Honda, you might want to read this first.

http://www.aa1car.com/library/battery_disconnect_problems.htm

Tester

6

I never had a problem disconnecting the battery when I had an '01 Civic.

7

That’s for the TC lock-up function. It improves mpg, but worse case you can probably make do without it working if you can’t figure out how to fix the problem.

The solenoid is just a coil of wire, electrically speaking. When current flows in that wire it creates a magnetic force and activates the solenoid valve. What the codes is saying is that the computer believes that coil’s continuity is broken somewhere, and so it won’t conduct electricity. The disconnection could be inside the solenoid, but it could also be from the computer to the solenoid, or the ground from the solenoid to the chassis ground. So break it into three sections. Easiest is to check section number 2, the solenoid itself. The coil of wire inside the solenoid should measure less than 30 ohms I’d guess. Since this is a replacement transmission, double check that the transmission is properly grounded to the chassis too.

Another idea, try Googling “Hot Rod to the rescue transmission solenoid” . They had an article on a similar problem in the last few months.

8

George, if you’re talking about what you mentioned a few days ago, that article was about a highly modified car

It was also a completely different scenario

9

Non-working TC clutch should eventually throw a check engine light. (It did on my old Civic when a TC seal failed.)

10

There is no drivability issue with the car as far as I can tell. did disconnect the ECU fuse in the engine compartment to clear the code but it kept coming back. I think i will follow up with George`s recommendation. Check the ground connection from transmission to chassis.

11

There is no drivability issue with the car as far as I can tell. did disconnect the ECU fuse in the engine compartment to clear the code but it kept coming back. I think i will follow up with George`s recommendation. Check the ground connection from transmission to chassis. I already changed the solenoid multiple times, thanks to Junk yards. ohh, the solenoid, it is the single one on top of the transmission correct? Do i need to check the shifting solenoids in the bottom also? and how about the linear dual solenoids? do they need to be checked?

12

seems like there is no drivability issue with the car. drives and shifts fine…

13

Disconnect the solenoid (if that’s easy to do) and measure its internal coil resistance. What do you measure (in ohms)?

If the trans fluid level is low or dirty of course fix that problem first.

If the solenoid seems the correct resistance, consider that harness wiring to it is open or shorted. The transmission must be properly grounded to the chassis for the solenoid to work correctly.