I have had a 87 aerostar for the last year. It has been running great with no problems at all. Iam in Puerto Vallarata Mexico . While driving today the emiss dummy light came on today and I don't know why. What would cause the light to come on. Thank you

 

It does that when something in the engine control system isn't working right. It can be caused by a number of things. You should try to run the EEC self test and see what kind of error codes show up. That will help you start the diagnosis.

Just a WAG, if it's still using the original oxygen sensor, you should probably replace it. It is used by the EEC as primary feedback to control the engine. My first one failed at about 25000 miles, and that caused the CEL to come on.

 

Thanks for the quick reply.

I am about 260 miles from home. Will it hurt the van if I drive home? I would rather have my mechanic check than a stranger.

 

I've had to do something similar; hundreds of miles away from home, and the light comes on and will not go off. I drove home like that without much drama. If the engine is otherwise running OK, I think the worse that would happen is you get lousy gas mileage and/or pollute more than normal.

If my case, it was the oxygen sensor.

 

I will attempt the ride home. Thanks for your help.

 

probably a sensor gone bad, the light is just a warning that something needs to be replaced or serviced. Just drive it and try to get the Service Code.

 

I made it home with no problems except very bad gas mileage. The computer readout said I was running very lean. My mechanic and I decided to do a complete turn-up, plugs, fuel and air filters. He should be able to get parts Monday in Guadalajara. I will find out Tuesday if everything is good.

Thanks you all for your advice.

 

I just got the van back from the shop. She is running great. My mechanic reset and cleared all the codes on the computer but the EMISS light still is lit.

How do we turn the off dummy light? Does it reset on its own after a certain amount of miles driven?

Muchos Gracias

 

Did they actually read the codes to find out what the problem was?

On mine, the problem was traced to a bad oxygen sensor, and was replaced by the dealer under ESP. I don't know if they had to explicitly turn it off, or it went off by itself. What i do know is this: before replacing the sensor, the light would be off when I first start the engine. Then after running for a short while the light would come on. With the new oxygen sensor, the light does not come on after the engine is re-started.

If your light is off when you first start the engine, then comes on after running for a couple minutes, there is still a problem.

 

It does not sound that any of the parts that would trigger a CEL were replaced, so I am not surprised that the light is still on.

As mentioned, FIRST STEP is to pull the codes and then repair / fix / replace the parts or issue that is setting the code(s), which in turn is turning on the CEL light.

Anything else and it is like shooting darts at a dart board blindfolded.

Not that a tune up is not a good idea to start.

David

 

David

After driving 50 plus miles and disconnecting the battery for 1 minute the EMISS light is still on.

I just returned from my mechanic. We hooked up the computer and ran the cycle of tests. The van passed with no codes present. How do I get the light to reset and turn off?

 

There is a small module under the dash with a button that will reset the EMISS light. That light is different from a check engine light and will come on when the module thinks it's time for it. IIRC a 86 Aerostar or any other Ford product of that vintage does not have a CEL. I used to have a 87 Topaz and it didn't have a CEL or EMISS light. here is how to reset the EMISS light

 

I just learned something! Great info. Thanks

David

 

Success, no more dummy light. I guess you can call this the original "dummy light" for the suckered customers. Ford was smart as it got customers into the dealers for service. It got me the tune up that I really did need but didn't realize I needed.

Thank you very much.

 

Ford wasnt trying to "sucker" customers, the early fuel injection and smog control systems were mediocre at best and required periodic maintenance to maintain federal emission standards.