2008 combination/related problem

At odd times and various speeds, there will be the sound of the ESC engaging, xmission shifts to low, ESC off light comes on, will not upshift. No codes thrown. If you stop, turn engine off then restart immediately all is fine til the next time. No pattern to this event and it may be weeks between happenings.
Any guesses are appreciated.

I suggest you register with
http://www.kiatechinfo.com
there you can download lots of technical info including troubleshooting. I might help....
good luck


EDIT

Here is what I found (only part) under BRAKE ...Esc

1. In principle, ESC and TCS controls are prohibited in case of ABS failure.
2. When ESC or TCS fails, only the failed system control is prohibited.
3. However, when the solenoid valve relay should be turned off in case of ESC failure, refer to the ABS fail-safe.
4. Information on ABS fail-safe is identical to the fail-safe in systems where ESC is not installed.

MEMORY OF FAIL CODE1. It keeps the code as far as the backup lamp power is connected. (O)
2. It keeps the code as far as the HCU power is on. (X)

FAILURE CHECKUP1. Initial checkup is performed immediately after the HECU power on.
2. Valve relay checkup is performed immediately after the IG2 ON.
3. It executes the checkup all the time while the IG2 power is on.
4. Initial checkup is made in the following cases.(1) When the failure is not detected now
(2) When ABS and ESC are not in control.
(3) Initial checkup is not made after ECU power on.
(4) If the vehicle speed is over 5 mph(8 km/h) when the brake lamp switch is off.
(5) When the vehicle speed is over 24.8 mph(40 km/h).

5. Though, it keeps on checkup even if the brake lamp switch is on.
6. When performing ABS or ESC control before the initial checkup, stop the initial checkup and wait for the HECU power input again.
7. Judge failure in the following cases.(1) When the power is normal.
(2) From the point in which the vehicle speed reaches 4.9 mph(8 km/h) after HECU power on.


COUNTERMEASURES IN FAIL1. Turn the system down and perform the following actions and wait for HECU power OFF.
2. Turn the valve relay off.
3. Stop the control during the operation and do not execute any until the normal condition recovers.

WARNING LAMP ON1. ABS warning lamp turns on when ABS is fail.
2. ESC operation lamp turns on and ESC OFF warning lamp blinks when ESC is fail.

When power voltage and valve relay voltage are abnormal, input/output related failure judgment is not

LMP thanks for the info and referral to the web site. This has been a great help and hopefully the problem will not reoccure.