Automotive electronics questions for newbie

Thread Starter

Joseph Beasley 1

Joined Feb 16, 2017
14
Hello, I am interested in learning about automotive electronics and I have some questions about car ECUs and how they work.

Firstly, what type of hardware and software does a cars engine control unit operate on? What is a typical micro architecture of a auto ECU? are the architectures common like ARM or MIPS or is it proprietary?
What type of ' operating system ' do they use?

I have read a very little about lookup tables and ROMS for car engine controllers, can you tell me more about these? what type of code are they written in? Assembly ?

Also how does the On-board Diagnostics system work?
1: where is the " host " or brains of the OBD2 system located? Is it a part of the main engine controller or a separate unit?

2: Does an ECU contain redundant self diagnosis circuitry? As in if a fault with the ECU occurs how can, or does it diagnose itself or would your OBD bus be offline/ dead?
3: is the ECU aware of other controllers on the vehicle? for instance if a fault occurs with another controller like the ABS or Airbag system, does the ECU know and does it relay this signal to OBDII port?
Are things like ABS, SRS Airbag, Electronic Stability / Electronic Traction control tested through the OBDII bus or do they have their own diag circuitry?
 

JUNELER

Joined Jul 13, 2015
183
Hi,
First what type of a car you are referring to. Second this Ecu is a propriety of the vehicle manufacturer
like Toyota .They will not allow you to learn and do it yourself in diagnosing.

How they will earned a money in maintenance... if anybody is allowed.

TRY to google all the component parts .
 

Thread Starter

Joseph Beasley 1

Joined Feb 16, 2017
14
Hi,
First what type of a car you are referring to. Second this Ecu is a propriety of the vehicle manufacturer
like Toyota .They will not allow you to learn and do it yourself in diagnosing.

How they will earned a money in maintenance... if anybody is allowed.

TRY to google all the component parts .
Well I'm asking as a general idea for ' modern ' passenger cars. Anything made from the late 80's onwards that is equipped with an EFI engine and *mostly* standardized diagnostics. As well as typical safety features such as antilock brakes, SRS Airbag Etc.

For a specific vehicle, let's say * my car * a 1998 Toyota Corolla

What I consider a ' modern ' car:

• Digital Multiport Fuel Injection with or without ECT transmission.

• Anti-lock Braking System with or w/o electronic stability control

• SRS Airbag

• either OEM specific or standard *OBD2* diagnostics
 
Last edited by a moderator:

Tonyr1084

Joined Sep 24, 2015
4,554
Sorry, I don't have an answer to your question. However, being a long time driver of Toyota's, I had been hoping someone would develop an after-market tuner. Finally (a few years ago) someone cracked Toyota's code and developed a tuner. The cost? A mere $800 plus. Why? Because they spent about six years working to break the code Toyota was using. There are after market tuners available for MOST cars. I'd have to imagine that many of them use the same or a very similar code in their controllers. However, Toyota had one that was in a completely different language.

I only share my comments because I suspect that many automakers have some proprietary coding. It may have been broken a long time ago but the point is that it's probably going to be different to some degree for every make and model. Perhaps your goal should be to target a single automotive coding system and work that out. THEN add a different one and compare.

ME? I don't have the answer. But that never shuts me up.
 

drc_567

Joined Dec 29, 2008
848
... interesting topic ... There is a forum section labeled automotive electronics ... which may yield more detailed comments.
 
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