Update :
I'm still troubleshooting the motherboard, however, in the meantime, I was still confused why the VFS didn't function on a 5V battery, so I borrowed a DC variable power supply, coarsed the voltage on 5V, connected the VFS and it worked! So I think the reason it didn't work on 5V nor 9V battery is because it didn't get enough current with those batteries.

 

So I think the reason it didn't work on 5V nor 9V battery is because it didn't get enough current with those batteries.

Could be correct, or it was stuck and it didn’t free up until you hit it with 12V. One way to confirm is to hook your 5v or 9v battery up again to see if it now works on them. If it does you could assume it was stuck.

 

I need some help, after I have troubleshoot the PCB without voltage, I need to connect it to power now and do some tests. But first, I need to find the power pin, however, because I don't have the schematics of the ECU, I tried to attach the test lead to the positive wire of the car battery and the other lead to the ECU pins, it didn't make any beep. As I need to know which pin is the power pin. Also, I found the ground pin when I attached it to the negative wire of the car battery. Any ideas why it didn't beep?

I might have a faint idea of where the power pin could be, but I wanted to double check with this method if my predictions are right.

 

Any ideas why it didn't beep?

First you’d need the ignition switch turned to ON position, to give a path from positive terminal to components like the ECU, etc.. BUT when reading continuity with switch ON, there could be several pins at ECU connector that will show continuity but won’t be the actual power pin. That’s because continuity can be read thru things like coils, solenoids, light bulbs and etc., whose paths are also opened when switch turn to ON position.

A better way to find out is connect the battery wires to battery post, test pins of ECU for power and note if any has power with switch OFF. That would be the constant power source designed to maintain (short term) memory, which is NOT the one you’d want to supply power to. Then turn ignition switch to ON position and note the additional connector pin that received power, which would be the intended power pin for ECU operation and the one that you would want to attach power to.

 

I have important info in this link :

AutoHex Online Help: Hyundai i20(PB) 2011 Fault Code: p0748

but because Adobe flash isn't working, I cannot see the diagnostic circuit diagram, and the signal waveform of the VFS. Can you see it guys?

 

 

Thank you 🙏 much appreciated

 

Still haven't reach a solution for the PCB. However, in the meanwhile I went shopping for gear oil. In my owner manual, it recommends SP-III type oil as shown below :

I looked everywhere and asked the shop salesman about SP-III, he says only SP-IV is available in all the shops. This is its picture :

Can I use this instead? When I searched about it online, some posts says SP-IV is not a replacement for SP-III.

I also asked for the price of a new original ECU, it cost $1500 😅 I better fix that ECU I have!

 

I'm not sure about the tranny oil but you can purchase a used ecu from eBay for $50 to $80.
they're not hard to find as long as you match up the numbers it will work.
Heres an example of the spare I got so that you see all numbers match and the spare works perfectly on the car.

Good luck on choosing which tranny oil for the car. 🤞🙏🏽👍

 

It was recommended to me to buy Castrol Transmax Multi-Import, however, it will ship in September and it's too pricy. So I found this instead Motul MTL105784 Multi ATF Transmission Oil and it has the required specification SP-III in the back of the image as below :

The only difference is, it's written KIA ATF SPIII, whereas I have in my owner manual DIAMOND ATF SP-III, so I hope there isn't much difference. This is the oil front cover :

 

SP3, all the same Kia, Hyundai, Diamond, Mitsubishi.

 

Those ribbon harnesses can have bad solder joints though I think it was early years pre-2007. A bad harness would trigger a code and throw it into limp if it can't see a solenoid connected. And if i's a bad solder it also would have a good chance of being intermittent due to heat and vibration. If you have not checked the internal harness it may pay to do so though if it's intermittent connection it may pass as good.

 

Amazon sent me wrong item 😕 They sent me ATF VI, thats like 3 levels above III.

Just bought 4 quantities of this product :

Mitsubishi Diamond ATF SP III Transmission Fluid | MAPerformance

Mitsubishi ATF SP III MIT MZ320200. This is a more developed version with better low temperature properties and longer drain life intervals and shift durability.

www.maperformance.com

Let's hope they get this one right.

 

That could be a multi vehicle blend. The data sheet does state SP II, III and IV plus a long list of other makes.

 

Yeah you're right they did mention that

Though in the back cover they didn't say anything. I saw SP-IV and thought its not compatible

 

It's most likely SP4 equivalent more than the SP3.. I've read elsewhere for sp4 but the genuine Mitsubishi SP3 will be correct. Those older 4 and 5 speed hyundai boxes are in fact based on Mitsubishi designs and specs.

 

is common problem with kia and hyundai, inside the ECU replace 100u 35v capacitor and 220u 35v if have it, and TLE6288 R. should soft the problem

 

Hi i have same problem code dtc p0748
Kia rio 2014

 

What can I do

 

Open your pcm, replace all capacitors and look for broken circuit, ask for help from laptop repair guy. Below are my repair pics
Guys, its the pcm, open it and replace all 4 capacitors and look for broken circuit burnt by the original leaked caps, ask help from the laptop repair guy. Look for vids from youtube, mostly indian guys upload thier repair, we also repair this kind of common issue here in the philippines

 

Car model : Accent 2012
Driving amount: 160,452 Kilometers

I started first to notice there is a strong shake from the whole car body when I shift from P to R and then to D every time, but then when I changed the gear to manual, it was on 3rd shift and it won't shift down or up while driving. And now it's stuck on the 3rd shift while driving or when I'm on Park mode.

I have made a computer diagnosis and I got this error :
P0748 : Pressure control solenoid valve (Vfs) 'A' Electrical

Note : There's no error icon showing on the dashboard

Specs : Engine is 4-Cyl, 1.4L and Transmission is : 4-speed automatic

How can I solve this problem?

Also, I don't really have much money, maximum I can spend to fix this car is $200. Is it possible that I fix it myself to save money?

Car model : Accent 2012
Driving amount: 160,452 Kilometers

I started first to notice there is a strong shake from the whole car body when I shift from P to R and then to D every time, but then when I changed the gear to manual, it was on 3rd shift and it won't shift down or up while driving. And now it's stuck on the 3rd shift while driving or when I'm on Park mode.

I have made a computer diagnosis and I got this error :
P0748 : Pressure control solenoid valve (Vfs) 'A' Electrical

Note : There's no error icon showing on the dashboard

Specs : Engine is 4-Cyl, 1.4L and Transmission is : 4-speed automatic

How can I solve this problem?

Also, I don't really have much money, maximum I can spend to fix this car is $200. Is it possible that I fix it myself to save
Probly late did you check the transmission oil temperature sensor. And if late to the party happened or what was issue

 

Hi everyone. I have the same problem. Can anyone share
the part number of the solenoid valve?

Hi everyone. I have the same problem. Can anyone share
the part number of the solenoid valve?

Its the 1.4, 4 speed