Hyundai Atos 1999 obd connector pinout.

AshSama said:

Hey guys,
I'm wondering if someone knows the protocols of pin 1, 8, 20 of the Atos -99?
It also does...

Click to expand...

Hi Greg,

Welcome to the forum.

The reason your ELM327 adapter isn't picking anything up is simply because a 1999 Hyundai Atos is not OBDII/EOBD compliant, even if it has the 16-pin connector.

In that era (pre-2001 for petrol in EU/Asia), Hyundai used the physical ISO 9141-2 layer (K-Line), but the communication protocol is manufacturer-specific. The ELM327 looks for standard legislated PIDs (like Mode 01, PID 0C for RPM), which the ECU won't reply to. The Autocom works because it knows the specific initialization sequence (handshake) to wake up the modules and the specific memory addresses to read parameters from.

Regarding the pinout, there is a slight confusion in your post. A standard OBDII (J1962) connector only has 16 pins. If you are seeing a "Pin 20", you might be looking at the rectangular diagnostic connector under the hood (common on older Kia/Hyundai), or perhaps miscounting the pins on the 16-pin port?

Assuming you are talking about the standard 16-pin port inside the cabin, here is the typical layout for that era of Hyundai:

• Pin 7: Engine ECU (K-Line). This is where the main data comes from.
• Pin 8: SRS / Airbag (K-Line).
• Pin 12: ABS (K-Line).
• Pin 1: Often used for ABS or Traction control on older implementations if not on Pin 12. On some models, Pin 1 is a generic "Check" trigger line.
• Pin 16: +12V
• Pin 4/5: Ground

If you actually have the 20-pin rectangular connector in the engine bay (Diagnostic Link Connector), the pinout is different:

• Pin 20: Usually a Check Engine Light monitor or similar output.

To summarize the protocols:
They are all physically ISO 9141 (K-Line) logic (0-12V switching), but they run on independent lines rather than a CAN bus network.

• Pin 1: Likely ABS (Proprietary Hyundai Protocol)
• Pin 8: SRS/Airbag (Proprietary Hyundai Protocol)

If you want to diagnose this with a cheap tool, you can't use a standard ELM327 + Torque/CarScanner. You need a tool that supports "Cascade" (an emulator for Hi-Scan Pro) with an FTDI K-Line cable, or stick with the Autocom/Delphi unit you have, as it multiplexes the K-Line to the correct pins (1, 7, 8, 12) automatically.

Double-check that "Pin 20" and let us know which connector shape you are looking at.

Sorry I meant pin 12 and not 20.
Thank you a bunch for the extensive reply!
The thought I had was to modifiy an ELM to the correct pins, but if it doesn't follow ELM protocol then it wouldn't matter....
Cheers Mate!

AshSama said:

Sorry I meant pin 12 and not 20.
Thank you a bunch for the extensive reply!
The thought I had was to...

Click to expand...

No worries, Pin 12 makes perfect sense—that is indeed the ABS line on these older Hyundais.

You are spot on regarding the ELM modification. It would be a waste of time.

Here is the technical reason why:
The ELM327 chip (and its many clones) acts as an interpreter. You send it a command (like "Show me RPM"), and it translates that into a specific hex string based on OBDII standards (ISO 15031). The 1999 Atos ECU doesn't understand those standard requests. It requires a specific "wake up" baud rate and a proprietary initialization byte sequence that the ELM firmware simply doesn't know how to generate.

However, your idea of switching pins is actually correct, you just have the wrong adapter.

If you want a cheap DIY solution that works like the dealer tool, look into this setup:

• Hardware: A generic "VAG KKL" cable (USB to OBDII). These are usually blue and cost about $10. Try to get one with an FTDI chip.
• Software: A program called Cascade 0.9.4. This software emulates the original "Hi-Scan Pro" dealer tool on a Windows laptop.

Here is where your pin mоd comes in:
The KKL cable is a "dumb" pass-through (unlike the ELM). It allows the software to control the communication bit-by-bit.
1. The KKL cable normally communicates on Pin 7 (Engine).
2. To read your ABS, you would need to open the KKL cable and solder a switch (or move the wire) to connect the K-Line to Pin 12.
3. To read Airbag, switch it to Pin 8.

So, if you are handy with a soldering iron, ditch the ELM and grab a KKL cable. That will get you into all modules on that '99 Atos.

Cheers!