Engine light is on with code P0700 and P0740 TCC issue

[Phuc Nguyen]

2004 Jeep Liberty, 3.7L.
First, code P0137, O2 sensor 1, bank2. This issue is corrected and then code P0700 and P0740 came up.

At 70mph, rpm varies between 2200 to 2500, seems like the torque converter did not lock-up.
I know this for sure because I have a 2005 Jeep Liberty to compare with.

1). Replaced transmission fluid and filter. Did not correct the issue.
2). Replaced valve body, parts# 04800171AA, fluid and filter. Did not correct the issue.
3). Checked all wirings, no visible sign of corrosion or frayed.
4). Opened up PCM unit, did not see any loose, burnt or corrosion.

Main issue is the Jeep would not pass inspection with engine light on in Pennsylvania.

Does anyone has similar sympton on these codes or what reccomendation should I go next.
Any input is greatly appreciated.


* Update, 12/17/2019, I drove my 2005 Liberty to pick up my daughter home from college, about 250 miles round trip. During the trip, 90% is turnpike highway, I pay close attention to the behavior of this 05 Liberty, such as speed and RPM.

After comparison, my 04 Liberty is the about the same. At 70 mph, RPM is about 2200 and increases between 200-400 on incline and return to 2200 on flat roadways. That means PCM did send signal to valvebody/sensor for a lock-up but torque converter internal clutch is slipping.

My last two options are:
5). Replace torque converter. If this step does not fix the issue, step 6 will be my final option.
6). Replace the transmission.

Will update with my result and thank you everyone who reads this post.

 

[lfhoward]

Welcome from a fellow Pennsylvanian. Sorry I don’t know the answer to your question. I’d probably take it to my mechanic at this point. I can do basic engine maintenance but transmissions are a little out of my comfort zone.

 

[Phuc Nguyen]

2004 Jeep Liberty, 3.7L.
First, code P0137, O2 sensor 1, bank2. This issue is corrected and then code P0700 and P0740 came up.

At 70mph, rpm varies between 2200 to 2500, seems like the torque converter did not lock-up.
I know this for sure because I have a 2005 Jeep Liberty to compare with.

1). Replaced transmission fluid and filter. Did not correct the issue.
2). Replaced valve body, parts# 04800171AA, fluid and filter. Did not correct the issue.
3). Checked all wirings, no visible sign of corrosion or frayed.
4). Opened up PCM unit, did not see any loose, burnt or corrosion.

Main issue is the Jeep would not pass inspection with engine light on in Pennsylvania.

Does anyone has similar sympton on these codes or what reccomendation should I go next.
Any input is greatly appreciated.


* Update, 12/17/2019, I drove my 2005 Liberty to pick up my daughter home from college, about 250 miles round trip. During the trip, 90% is turnpike highway, I pay close attention to the behavior of this 05 Liberty, such as speed and RPM.

After comparison, my 04 Liberty is the about the same. At 70 mph, RPM is about 2200 and increases between 200-400 on incline and return to 2200 on flat roadways. That means PCM did send signal to valvebody/sensor for a lock and -up but torque converter internal clutch is slipping.

My last two options are:
5). Replace torque converter. If this step does not fix the issue, step 6 will be my final option.
6). Replace the transmission.

Will update with my result and thank you everyone who reads this post.

* Update, 2/27/2020, weather in South Central PA was giving me a break to replace torque converter.
Yes, indeed it was torque converter issue. No more slipping on highway speed and have a lot of torque going uphill.
Got it from Autozone for $170, sold by Precision from Erie, Pennsylvania.