Self Diagnosis Flash Lights for Mitsubishi Lancer 4G15

After playing with the OBDII port of my car and with the help from WWW, I could activate the self diagnosis mode of the Mitsubishi Lancer 4G15 ECU.

By doing a simple routine, we can read the error codes recorded in the ECU. The error codes are interpreted from the pattern of flashing of the Engine Check Light (ECL) in the dash.

The above pic shows the schematic of the 16 Pin OBDII port. For the Mitsubishi lancer 4G15, only pins 1, 4, 5, 7, 9, 16 are available. The OBDII port of my car is located under the dash board on the driver side- straight under the steering. We have to lie down on the car floor to clearly see it though.

Steps:

1. Turn ignition key to OFF position.

2. Short pin 1 and pin 4. We can use a metallic paper clip- inert one end of the clip to pin 1 and other to pin 4.

3. Turn ignition key to ON position.

The Check engine light in the dash will blink in a pattern. If there are no error codes, the light will stay on for 0.5 seconds, then stay off for 1 second and this pattern will repeat.

If there are error codes, then the error code can be interpreted from the pattern. A 0.5 seconds duration of illumination represents a unit of 10 and a 0.2 seconds illumination represent a unit of 1.

In my car, there was a 0.5 second duration illumination followed by four 0.2 seconds duration illuminations. Which means the error code was 14 !.

A table which shows the error codes and reason. I don't say I have 100% faith about the authenticity of this data.

11 Oxygen sensor

12 Intake air flow sensor

13 Intake air temperature sensor

14 Throttle position sensor

15 ISC motor position sensor

21 Engine coolant temperature sensor

22 Engine speed sensor

23 TDC sensor

24 Vehicle speed sensor

25 Barometric pressure sensor

31 Knock sensor

41 Injector circuit

42 Fuel pump relay

43 EGR

44 Ignition coil

36 Ignition circuit

From this, error code detected for my car was Throttle position sensor error. I need to verify this with an MUTII scanner used by Mitsubishi A.S.S. If both my finding and the tool are having an agreement, then we can conclude that the above table is correct.

PS: To clear the error codes, the -ve terminal of the battery should be disconned for more than 16sec. I havnt done this since I am waiting to go to Mitsu A.S.S and confirm the error code is indeed 14.

Update: Even after repeated visits to the Mitsu A.S.S in TVM, couldnt verify the error code as they dont have the MUT scanner with them at the moment. After reading some more reliable sources online, it seems I can almost conclude that the error is indeed TPS Error.

OBDII Jungle- prologue

Some couple of months back, I was bitten by the thought of learning about engine management systems and the procedure for reading trouble codes and engine parameters through the OBDII port or the Data Link Locator. I am specifically interested in reading different engine parameters from the ECU of my Mitsubishi Lancer 4G15. If success, then the live engine data from different vehicle sensors could be displayed on a screen inside the car(Another reason to convince myself for a CarPC). There are host of engine parameters like rpm, coolant temp, air flow (MAF), Inlet Air Temp (IAT), AFR that could be read. With all the cool live info, my Car will be a Bond Car -:)

The concept is simple. In a modern day automobile, the ECU is sort of a computer which virtually controls every single system. It reads from different sensors like, Inlet air temp, Air flow, fuel temp etc. Based on the input values, it decides on the amount of fuel to be injected, the ignition timing (when that fuel to be burned) etc so that engine burns fuel optimally at all times. In simple terms, ECU read signals from different sensors and based on the readings, fed the engine optimally. It is the sensor values that the ECU reads is what I am interested in. Through a port called the OBDII port or Data Link Locator (DLC) or whatever, we can read the values that ECU reads- realtime. This port is a standard for most of the passenger cars after 1996. OBDII is the protocol used to communicate with this interface. Mitsubishi vehicles uses a proprietary protocol called MUT over OBDII. My car is believed to be using MUTII protocol.

During the operation of vehicle, if the ECU detects any malfunction in any sensor readings, it stores the corresponding error codes in it so that a technician can diagnose it later.

After a bit of googling and understanding the above stuff and some more, I started the search for a cheap option to read data through the DLC. Basically a cable-laptop-software combonation. Cable would connect the laptop with the OBDII port and the software would read and display data. Simple. I came across a software called EVOSCAN (google to get link). There were different cables available, starting from read-only cables to more costly read-write cables.

The cable I needed was OpenPort 1.3D, which is a read-only cable. Ordered one by spending around $67. The cable was to be shipped from NZ. Made a mistake in choosing the cheap shipping option without Tracking. Cable was not delivered. First step is a failure. But everybody falls the first time.

Forgot the entire stuff and one day, the dream of the bond car stuck again. This time decided to try to learn how OBDII interface works. Spent hours reading different forums. Found some interesting links where the circuit designs for the interface cable is available. A Home made MUTII datalogging cable sounds cool. After scouting the WWW for days, I came to understand one thing. Its pure electronics- thats Spanish to me(I am a mechanical engineer destined to work in IT). But then I have learned electronics/electrical more than I have ever learned in my engineering days. I dont fear PCBs anymore.

Some interesting links.

http://en.wikipedia.org/wiki/On-board_diagnostics

http://www.myrollingroad.com/cmps_index.php

http://evoscan.com/technical-vehicle-manuals

http://www.aktivematrix.com/blog/