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Roy, import/domestic specialest
Category: Car
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Experience:  ASE master tech for 40 years
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I have 1997 Hyundai Sonata V6 auto trans, 80k miles. Trans

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I have 1997 Hyundai Sonata V6 auto trans, 80k miles. Trans shifts late & hard into 2nd, and at times will not shift to 4th but will stay into 3rd sensing a load (as if under heavy acceleration). When trans is stuck in 3rd, I can turn the ignition key off and back on and shift will then be normal. I suspect this is an electrical shift silanoid. I have changed trans fluid and filter but no change. Seems to shift better cold but gets worse warmed up.
good evening my name is Roy and I will help you tonight.

I found a TSB from the factory on your issue. It is a issue with the pulse generator. Below is a copy of it. I would call the dealer and see if there is any warranty on this. there may be but it is on a case by case.



Number: 98-40-002

Date: APRIL, 1998

Model: ALL

This TSB revises TSB # 97-40-025-1 to provide additional diagnosis procedures


The following conditions may be caused by an improperly functioning pulse generator. The conditions may be intermittent and difficult to duplicate.

^ Delayed or erratic 1-2 shift, with engine hot or cold
^ Harsh 1-2 shift
^ Harsh 2-1 downshift, at a higher speed than the normally scheduled downshift
^ Erratic downshift during light acceleration
^ Third-gear "fail-safe condition and/or "Check Engine" light on
^ Bucking and/or hesitation
The following diagnostic codes (DTC) may be stored in memory in the transaxle control module (TCM):


P0717 31 and/or 81 No pulse generator-A signal
P0722 32 and/or 82 No pulse generator-B signal
Note 1 :For Non-OBD II vehicles, always check the "Transaxle" menu in the HDS Scan Tool for additional codes.
Note 2: The following DTCs may be induced by an incorrect output of the PG-B and do not necessarily indicate a mechanical condition in the transaxle.
P0732 A/T 2nd gear ratio problem
P0733 A/T 3rd gear ratio problem
P0734 A/T 4th gear ratio problem
P1624 MIL- On request from TCM
After repairs are made to the pulse generator, clear the codes and test drive the vehicle for two driving cycles*. If the DTCs do not return, the codes were induced by the incorrect output of the PG-B.

* A driving cycle is defined as:

^ The engine is started cold (coolant at ambient temperature)
^ The coolant temperature rises to 160°F
^ The fuel system goes into closed loop. (To determine closed loop, attach the HDS Scan Tool to the data link connector (DLC), select "Engine", "Codes and Data" and "Data" menus and monitor "Fuel Sys1" until the readout is "CL")

1. Disconnect the pulse generator connector.

2. Using small needle nose pliers, gently twist the male pins in the pulse generator main connector approximately ten (10) degrees clockwise to ensure electrical contact.
3. Reconnect the pulse generator connector.
4. Remove the connector from the transaxle mounting bracket. Leave the connector loose on the transaxle case to prevent any tension on the harness.
5. Verify the correct operation of the pulse generator according to the procedure shown.
A. Connect the HDS Scan Tool to the DLC.
B. From the Menu, select "4-Speed Trans", "Codes and Data" and "Data".
C. Drive the vehicle at a steady speed in third gear with the overdrive switch off while an assistant monitors PG-A and PG-B. Check that both PG-A and PG-B are approximately equal to the engine rpm in third gear. If so, the pulse generators are functioning properly.

Roy and other Car Specialists are ready to help you
Customer: replied 4 years ago.

Thanks Roy. I did try to find all of the recalls and service bullitins on this model and year. But like you said, there are some recalls or services they do only on customer complaints at the dealership. My wife just bought a new Elantra at a dealership near by, so I'll check with them on the info. you gave me. I was ready to pull the valve body off of the trans and start swapping out all of the electric components- this should be alot simpler. I'm going to go ahead and rate you and can always get back to you if there are further problems.

Speaking of additional problems, the EGR valve is throwing a code and the car has a light ruff idle. I don't have the car here to give you the code # but can get it in the morning. The vacume tubing to the EGR, as pictured on the diagram under the hood, had a bebe stuck in it and the air bleed valve the fo the EGR was broken. I replaced that air bleed valve, (little plastic -1tube in and two tubes out- with one of the 2 tubes out having a smaller orifice restricting the amount of forced vacuum to the EGR) thinking this was a simple fix...but no. EGR valve draws up too much at idle and idles even ruffer and sometimes dies. So I unpluged the vac line to the EGR and put a golf tee in it to stop the vacuum leak. (The car still passed California smog with the EGR unplugged-just well disguised!)

I can force the EGR valve open with my fingers and it does close all of the way. It's getting too much vacuum even with the new plastic piece and opens the EGR at idle causing the really ruff idle or car dies.

I'm 61 years old and have been an auto tech my whole life-but you never know it all!

Customer: replied 4 years ago.

Roy, is this something that a 'Good' repair shop can do or is this pretty much a dealership repair, due to the diag. computer/ HDS scan tool, reprograming and acessing TCM codes? I was only able to receive only one DTC- P0750 shift solenoid A.

Good morning a good shop should be able to handle this.


On the 750. check the resistance of the solenoid first before replacing. A lot of times, it is the actual harness that is the issue not the solenoid itself.


61, great, I got a year on you and going strong.