Engine light is on with code P0700 and P0740 TCC issue

[Phuc Nguyen]

I have an auxiliary transmission cooler on the front of my radiator that I added because I tow a lot. I can say that with the cooler, I see 125°F on the interstate highway (145 when towing), 165°F in mixed driving (185 when towing), and sometimes 220°F climbing a mountain on a forest road on a hot day. When towing my camper up that mountain I usually stop and let it cool off before it reaches 240°F, about halfway up. Having the mechanical cooling fan on the front of the water pump helps too, as that was part of the tow package. I added the fan. All the temperatures referenced above come from my Scangauge II.

Update, I trimmed and inverted the piston 1/8" off inside transmission oil cooler bypass valve, not sure any Jeepsters out there ever tried it,. Now transmission fluid temperature dropped significantly. Ambient temperature is 93°,

 

[Phuc Nguyen]

I have an auxiliary transmission cooler on the front of my radiator that I added because I tow a lot. I can say that with the cooler, I see 125°F on the interstate highway (145 when towing), 165°F in mixed driving (185 when towing), and sometimes 220°F climbing a mountain on a forest road on a hot day. When towing my camper up that mountain I usually stop and let it cool off before it reaches 240°F, about halfway up. Having the mechanical cooling fan on the front of the water pump helps too, as that was part of the tow package. I added the fan. All the temperatures referenced above come from my Scangauge II.

Transmission oil temperature update.
Cut off 1/8" off at end of thermostat piston and inverted inside transmission oil cooler bypass valve assembly.
Now transmission fluid temperature dropped significantly.
Outside ambient temperature is 93°F
Highway driving temperature, at 65+ mph, is 153°F
Local/mixed driving temperature is 160° - 168°F
Coolant temperature still at 208°F
Also, A/C is much cooler now.
Very happy with the outcome with transmission temperature.

Traction control light update.
After replacing front driver and passenger hubs/bearings, and make sure all cables are good, the Traction control light still lit up intermittently with a ding notification sound, not affected with driving at all.
Did not try the Jscan app due to not having enough data on Tracfone.
For now just take my mind away from it for a while, will look for more information on how to correct trouble code C1219.
Thanks for all your help and inputs.

 

[KJowner]

Strange it's getting so hot that you have had to make it push more oil through the cooler, is it slipping?

 

[Phuc Nguyen]

Strange it's getting so hot that you have had to make it push more oil through the cooler, is it slipping?

It's not slipping at all, my wife said that it's very warm on passenger floor board. When plug in the scanner and scroll through live data, for traction control light issue, that's when I notice the transmission oil temperature is high.
Now, it is more comfortable on front passenger floor board and the A/C is much cooler than before even outside temperature is 93°F.
Not sure how transmission oil cooler bypass assembly works, but happy with the conversion.

 

[Phuc Nguyen]

Update on "Traction Control Light" that comes on intermitently, between 20-30 mph, at slight left curve.

The hole things started when an airbag light came on, and right front wheel grinding, very hot not touchable, and melted right front ABS sensor wiring to the core.

After replaced clock springs, for airbag light, that's when traction control light appears.
Scan code using Innova 5510 scanner, DTC C1219, C1240 and C1243, all directed to "Steering Angle Sensor"

Here is the list of things that I've done:
Calibrate steering angle sensor, didn't help with traction control light.
Replace both front ABS sensor, didn't help with traction control light.
Replace both rear ABS sensor, didn't help with traction control light.
Replace both front hub/bearing with built in sensor, didn't help with traction control light.
Replace battery, didn't help with traction control light.
Heard whining sound fron engine compartment one morning after starting up, mistakenly, thought it was low on ATF fluid. Add fluid whining sound still there. Start the engine with serpentine belt removed, turned out, it was alternator bearing dried out.
Replace alternator, drain some ATF fluid to correct level, didn't help with traction control light.
Replace all wheel brake pads and rotors, didn't help with traction control light.
Last thing I did was replace brake light switch. Test drive with slight left turn, slight right turn, go straight and over bumps around 50 miles. So far traction control light hasn't show up yet. Hopefully will not.

I work around cars for over 50+ years, this is the first time I replace "brake light switch"

BTW, if any of you have 42RLE transmission with 13 bolt pan, get one with drain plug, it's much easier for changing fluid with less mess. I meant, not splashing over your hands and face.
Pan with drain plug, filter and gasket for less than $40 on Amazon website.

If you don't see any update, meaning mission accomplished.

Thank you everyone for your comments.

 

[lfhoward]

Nice work! I’m glad you were able to solve it.

 

[Phuc Nguyen]

Thanks, lfhoward. I drove over 500 miles round trip, this past weekend, from central PA to Williamsburg VA with a Harbor Freight trailer, full of daughter's college moving stuff, in the back without any issue, until turning into development at home with a speed limit of 25 mph, and that darn light came on. After replacing brake light switch, I drove over and over many times, same route that the light had been coming on, knock on wood, this time the light hasn't been on yet. Hopefully, it won't. Again, thank you.

 

[Phuc Nguyen]

Update on "Traction Control Light" that comes on intermitently, between 20-30 mph, at slight left curve.

The hole things started when an airbag light came on, and right front wheel grinding, very hot not touchable, and melted right front ABS sensor wiring to the core.

After replaced clock springs, for airbag light, that's when traction control light appears.
Scan code using Innova 5510 scanner, DTC C1219, C1240 and C1243, all directed to "Steering Angle Sensor"

Here is the list of things that I've done:
Calibrate steering angle sensor, didn't help with traction control light.
Replace both front ABS sensor, didn't help with traction control light.
Replace both rear ABS sensor, didn't help with traction control light.
Replace both front hub/bearing with built in sensor, didn't help with traction control light.
Replace battery, didn't help with traction control light.
Heard whining sound fron engine compartment one morning after starting up, mistakenly, thought it was low on ATF fluid. Add fluid whining sound still there. Start the engine with serpentine belt removed, turned out, it was alternator bearing dried out.
Replace alternator, drain some ATF fluid to correct level, didn't help with traction control light.
Replace all wheel brake pads and rotors, didn't help with traction control light.
Last thing I did was replace brake light switch. Test drive with slight left turn, slight right turn, go straight and over bumps around 50 miles. So far traction control light hasn't show up yet. Hopefully will not.

I work around cars for over 50+ years, this is the first time I replace "brake light switch"

BTW, if any of you have 42RLE transmission with 13 bolt pan, get one with drain plug, it's much easier for changing fluid with less mess. I meant, not splashing over your hands and face.
Pan with drain plug, filter and gasket for less than $40 on Amazon website.

If you don't see any update, meaning mission accomplished.

Thank you everyone for your comments.

Three days after the Sept 10 updated, traction control light came back. While trouble shooting, clocksprings went haywire. TC light would come on just by turning the steering left and right, while parked on the driveway.
Replace with another order of clocksprings from different seller, it makes a big difference.
Almost two weeks since, no more sign of TC light.
I've been looking in the wrong direction instead of trusting the scanner tells you where the issue is.

Hopefully, this TC issue is forever gone.