Transmission not shifting?

You need not wait. When the CEL indicates, the error would be stored in the computer and you can retrieve the trouble code even if it is not showing now.

DTC P1529: TCM REQUEST FOR MIL ON
Description
A communication line exists between the Engine Control Module (ECM) and the Transaxle Control Module (TCM).
The sole purpose of this communication line is for the TCM to notify the ECM to activate the Malfunction Indicator Lamp (MIL) when a serious transaxle failure has occurred.

DTC Detecting Condition

Inspection Procedures

"Â This is only a request from the TCM to turn the MIL ON. The fault code is stored in the TCM. The freeze frame data is stored in the ECM under the P1529 request code. Be sure to retrieve the freeze frame data before clearing code P1529 from the ECM.
"Â Check the transaxle system.

That means you need to rectify P0750.

DTC P0750: Low & Reverse Solenoid Valve Open Or Shorted

Description
The LR annulus gear and overdrive planetary carrier are locked to the LR brake when the LR solenoid operation.

The LR solenoid is operated at the transaxle range switch "P", "R", "N" and 1st gear.

DTC Detecting Condition

Specification

Schematic Diagram

Inspection Procedures
1. Check The DTC Of The LR Solenoid Valve

1. Connect Hi-Scan (pro) to data link connector.

2. Turn the ignition switch ON and monitor the DTC.

Is the DTC P0750 the output?

Yes: Go to next step.
No: Problem is intermittent or was repaired and engine control module memory was not cleared.

2. Check The ATF System
1. Check the automatic transmission fluid level.

Is the ATF level normal?

Yes: Go to next step.
No: Add or replace as necessary.

3. Check The LR Solenoid Valve Connector

1. Turn the ignition switch OFF and disconnect the solenoid valve connector.
2. Check that the solenoid valve connector for loose, poor connection, bent, corrosion, contamination, deterioration, or damage.
3. Is the solenoid valve connector normal?

Yes: Go to next step.
No: Repair or replace as necessary.

4. Check The LR Solenoid Valve Harness

1. Turn the ignition switch OFF and disconnect the solenoid valve connector and PCM connector.
2. Measure resistance between the solenoid valve connector terminal 6 and the PCM harness connector terminal 38.
3. Measure resistance between the solenoid valve connector terminal 10 and the PCM harness connector terminal 36.

"Â Specifications: below 1ohm

Is the LR solenoid valve harness normal?

Yes: Go to next step.
No: Repair or replace as necessary.

5. Replace The LR Solenoid Valve

"Â Use the Hi-Scan Pro to delete P0750 from memory in the PCM.
"Â Test drive the vehicle for two key-on the key-off driving cycles.

Does P0750 reset?

Yes: Go to next step.
No: Return the vehicle to the customer.

6. Replace The PCM

1. Disconnect the battery (-) terminal and disconnect the PCM connector.
2. Replace the PCM.

If you had not performed the testings, do so. The solenoids might not be faulty as the problem is intermittent. Quite often such problems are caused by wiring connection fault.

The connector at the transmission tends to collect water and over time, oxidation occurs at the connector terminals resulting in bad continuity. This would cause intermittent failure.

Show the guys at Hyundai the following diagram.

Hi Nathanallan,

Couple things. Can you provide your year, make, and model and then any codes that you have? I understand you are having the same issue but there are different causes for these types of symptoms so we need to evaluate your issue to determine if the cause is the same.

If would probably be best if you started a new thread and then just site this post as a similar issue by coping the address and pasting it into your own thread so we can be on the same page.

Thanks