When reading the ecm codes through the flashing service engine light how do u know when a code ends and a new one starts

 

When you short the two ports on the ALDL, then turn on the key. It will flash once, then twice, pause, then once again, then twice again, then pause, then once again, then twice again, then pause ... this is code 12, telling you that you are in diagnostic mode - it flashes 1 then 2, and it does this 3 times with a pause inbetween each - so you get code 12 a total of 3 times.

Then, it will pause again (a little longer pause), then do the next code, for instance 32, it will flash 3 times, pause, flash 2 times, pause, flash 3 times, pause, then 2 times, pause, flash 3 times, pause, then 2 times. That's code 32.

Then on to the next code.

After all codes are flashed like this, it will do the code 12 again, 3 times like before, to let you know it's at the end of diagnostic mode and that's all the codes. If you leave it on, it will start all over again.

So, from the beginning ....
Code 34, 26, 54:

Flash 1 - Flash 2
Flash 1 - Flash 2
Flash 1 - Flash 2

{code 12 - diags mode}

Flash 3 - Flash 4
Flash 3 - Flash 4
Flash 3 - Flash 4

{code 34}

Flash 2 - Flash 6
Flash 2 - Flash 6
Flash 2 - Flash 6

{code 26}

Flash 5 - Flash 4
Flash 5 - Flash 4
Flash 5 - Flash 4

{code 54}

Flash 1 - Flash 2
Flash 1 - Flash 2
Flash 1 - Flash 2

{code 12 - end diags}

Make sense?

 

Makes total sense but all I saw was flash pause flash flash...........over and over so does that mean it is just code 12 over and over

 

yep - means no codes have been set.

 

It doesn't mean code 12? Even if it doesnt I'm still totally baffled as to why this car won't start and when it does start y it won't stay on for more than 30 seconds

 

Well yes, it does mean code 12 - but code 12 is just signifying that you are going into diags mode, and then code 12 flashes again when going out of diags mode. Since there were no 'other' codes, there are no engine fault codes - that's what I meant by no codes.

 

If 12 is a trouble code how are u for sure that it's not an engine fault?

 

Because I read the procedure for getting the codes, and I read the codes listing, and I learned that code 12 is not an engine fault code, it's just letting you know you are entering and exiting the diagnostic mode.

{quoted from the tech article}

"Following this "12" code repeating three times will come any trouble codes stored, flashing each of them three times. If you do not see the "12" flash three times, your diagnostic circuit is defective. Some vehicles will display stored trouble codes, then "12" again, ..."

12. No reference pulses to Electronic Control Module (ECM).

"No reference pulses" refers to the fact that you are in diagnostic mode, and therefore the ECM is not receiving any of the normal "reference pulses" from the engine management sensors because you have shorted out the pins in the ALDL to put the system into diagnostic mode. The ECM cannot process new data from the sensors at the same time it's reporting currently stored fault codes, thus going into diagnostic mode cancels any current input from the sensors - thus "no reference pulses".

I guess it all boils down to a matter of trust. I don't generally answer posts with information unless I'm 90% confident that I know the correct answer. And when I am wrong, like everyone else here, I'm shot down quickly by another more knowledgable member. Many of us are quick to point out fault with other members answers if we think they are wrong - not to 'show anyone up', but in an effort to hopefully get the right info out there before someone wastes their time/money with incorrect information.

But I understand your concern - the internet is full of 12 year olds with nothing better to do than post all over the world. This resource is no different, there's as much wrong info as there is right. So don't feel like I'm trying to come off as some expert that's upset because you question my answer - you have to question EVERYTHING in this world! Like anything else in life, you just have to take what you get, mix in some common sense and decide your own fate.

Take it for what you will - what I (and all of TGO) offer is free (and sometimes may well be worth the cost ). But I have pulled many codes on many 3rd gen and 4th gen cars, and although I'm no ECM expert (as is evident by the fact that I removed all that crap and went carbed myself), I am confident that code 12 is not an engine fault code.

Concerning your overall issue with the car, at this point I'd say post up in the TPI section, and restate in as much detail as possible the issue, and what you've checked so far - I've helped about as much as I can since I'm just not very familiar with TPI. But feel free to PM me about anything, I may not have answers, but I'm happy to help you as best as I can. And good luck! These are great cars, like any car they have their issues, but don't give up - 3rd gens are well worth the effort!