Hello.

I have a 1988 2.8 V6 GT fiero and I am having a little problem with the "service engine soon" light

At the weekend I gave the car a service. (Air filter, oil filter, plugs and oil) I also had a go at interigating the ECM as the "service engine soon" light was on.

When I linked out the contacts the only code that repeatedly flashed was 12. According to my manual, that means that no error codes are stored.

I then tried to reset the system by unlugging the ECM for over 10 seconds. When I reconnected it the "service engine soon" light was still on.

How do I reset this light?
I can not find anywhere how I do this.

Can you help me?

Regards,

David Mcfarlane

I've never heard of "unplugging the ecm"? Just dis-connect the negative battery terminal for a minute and then re-connect next time. Did you try this yet?

I think that he was talking about pulling the ECM fuse from the fuse block. Yeah, as he said, disconnecting the ground cable from the battery should reset the ECM but if your problem still exists, it will set the light back on as soon as the fault is detected. Also, your engine will have to re-learn. It may idle funny for 5 or 10 minutes until it warms up and all sensors are sending good operating data.

[This message has been edited by Gordo (edited 07-26-2005).]

Hi David, Welcome to the Forum, yep you have to re-set ECM , by taking off either of the battery`s cables, wait a minute or 2, then re-install the cable, one note though--you don`t want to disconnect the ECM and re-connect it while it has power to it from the battery, it can blow out the ECM and or cause problems... This info came from the GM service manual . Hope it helps......

The ECM is definately reset. (I also disconnected the battery as well) There are no error codes stored. In diagnistic mode, it just keeps flashing the code 12.

Am am beginning to wonder if it is just me being stupid. When exactly should the "service engine soon" light be on?
Mine is on when the iginition is on but the engine is off. When I start the engine the light goes off.

Is this normal to indicate there is nothing wrong? Is the "service engine soon" light supposed to come on when the engine is running to indicate an error code.

Sorry if I sound stupid but this weekend was the first time I have done any work on the car (I only got the car last year) and too my knowledge I am the only person in Switzerland with one.

David

David, Don`t start the engine while your ECM is in the dio mode, do as you mentioned and use this as the key is on --engine off.. The service engine soon light will flash your codes then, it will also come on when you start/crank/turn key on... Then it goes out --if no codes. You won`t read codes from this . If the light does come on while running engine, you have a problem, then ground it out at the aldl and turn key on, don`t start engine---It will then flash your trouble codes, once done, it will go back to 12 Fix the problems, then disconnect battery to re-set ECM, then try again....

Thanks for that.
Just so I understand.
When should the service engine soon light come on to tell me there is a problem?
I am not talking about interogating it. (so before I touch a screwdriver or spanner)
I am trying to figure out if I have a problem with my car or that I am just being stupid.
On my car the following happens.
When I switch my ignition to on the "service engine soon" light comes on. (and stays on) Is this normal??
When I start the engine the light goes off and stays off.

Is this normal?

David

Yes that sounds normal.

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Hi David, To answer your question --Yes when you turn the ign/key on, the service engine soon light should come on, when you start the car it will go off. When you have a problem with the car, example after driving it a few or alot of miles, then for no reason while driving, the service engine soon light or SES as refered to comes on, then its time to check at your aldl plug for problems. If you just want to check for problems --then put it in the dio mode at the aldl---but turn the key on--only!! Don`t start engine, if it flashes 12 several times and nothing else--your ok, if after 3 times of it flashing 12 and it doesn`t follow that with any thing else--your ok>.........

David,

That is functioning normally.

When you start your engine the light is on for a bulb test only, with the engine running the light should go off as you stated.

No probs with your car by the sound of it.

Thanks guys.
You have really helped me alot. I think now I will check the bulbs in my dash board as the SES and hand brake lights are the only ones that come on which I switch the ignition on. Should anything else come on?

David

David your car is fine, enjoy it, if things go bang or light up when your doing 100 mph then stop

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