codykrr

Jeep cherokee sport- 2001
AW4 transmission
4.0liter inline 6.


Ok so for the past two weeks my CEL has came on with the p0740 code(TCC solenoid) I havent replaced it yet as I have been sicker than a dog. well today I was driving and noticed there is a noticable whining noise. not high pitched really just like a set of gears winding together.

I noticed at first when the CEL came on with the po740 code when I did a TC lock up test(hit brakes at 50mph or so to see if RPM increased) the RPMs dropped telling me the TC wasnt locking up...

But today did it again, and CEL is on, but now the TC is locking up as my rpm's raise at 50 mph as soon as I hit the brakes.

So...my first assumption is maybe a bad TC?

But Id hate to replace it to find out its a bad trans pump or something...

I did not notice this sound untill today. as of this afternoon the trans shifted fine, even locking up...just this whining noise.

it sounds like its coming from the bellhousing area, but to be honest I only looked into it for about 15 min before I said screw it and went inside(was cold and dark and Im still sick..lol)

when I bought the jeep the trans fluid was brown...motor oil brown. couldnt tell ya if it was burnt as I never smelt burnt trans fluid..

I dropped the pan, changed filter, new gasket and new dex mercon III. got about 5 quarts new fluid in.

I also cleaned the throttle body, IAC, and since getting the CEL light the first time I have adjusted the kickdown cable on the trans(button by the throttle body). I depressed tab, pushed slide back, opened throttle body with thumb...set.

Tomorrow I will try and re adjust it using the peddle instead as I was told that is now the "revised proper" way...

Any idea's is helpful!

also, whine seems to only do it in gear. but I will check for belt/accessory bearing/pully noise too...

CCKen

Here's a simple test you can perform to see if the TC is defective. It pointed to a defective TC when another person tried it several years ago (on another forum), but it should be noted that he didn't have a P0740 DTC. I do this test as a routine preventive maintenance activity.

Let the Jeep sit overnight to allow the tranny fluid to come to ambient outside air temp,

Remove the tranny dipstick and view the fluid level on the dipstick; it should be at or near the top of the dipstick. Replace dipstick,

Start the engine and pull the dipstick, the fluid level should have dropped to near the bottom of the dipstick.

If the fluid level remained at, or near, the top of the dipstick you can suspect the TC is defective. If the fluid level did drop to near the bottom, you should consider that solenoid "C" (Lock-up) is acting up (P0740).

CCKen

If you want to test the Lock-Up solenoid before just replacing it only to find out it didn't change anything, you can do this;

Refer to pics.

Access the Transmissin Control Assembly connector next to the tranny dipstick (see pic "TCA").

Unplug the TCA connectors,

Using a digital Ohmmeter read the resistance of solenoid "C" (Lock-Up Solenoid at the connector half that goes to the tranny. Refer to TCA Pinout.

Test:

Transmission Solenoid C, Lockup:

1. Set Digital Ohmmeter to 200 scale,

2. Measure resistance between pin 4 and engine ground.

3. Resistance should be between 11 and 15 Ohms.

If the resistance is outside of this range the solenoid is bad or the wiring from the connector to the solenoid is bad.

TCA location:



TCA Pinout: