Check Engine Light - 97 Aerostar

Loose gas cap caused check engine light to come on. Problem has been corrected. How can I reset the light without disconnecting the battery or using the diagnostic tool?

Reply to
Guv Bob
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IIRC, a few times of driving and parking will make it reset on it's own.

Reply to
SC Tom

As you continue to drive the car on qualified Drive Cycles (which is not the same thing as a trip), the computer will discover that the malfunction no longer exists, and the check engine light will go off by itself. Disconnecting the battery is not supposed to clear a check engine light on an OBD II car, although I seem to have seen my CEL clear while doing work with the battery disconnected.

In any case, OBD II does a constant monitor, and with qualified Drive Cycles, it will eventually turn the light off. You can do a Google search on OBD II DRIVE CYCLE to learn what is necessary. It is entirely possible that most of your trips might not meet the requirements of a drive cycle, and therefore the light will remain on for weeks, or months. If you use a scan tool to force the Reset, then the computer goes into Readiness Monitor Mode, and the same drive cycle requirement is invoked to bring the monitors to a ready state. If you are up against a smog test, then you will have the same problem with the CEL being on or with the readiness monitors being incomplete. If you disconnect the battery and clear the CEL, you still have the readiness monitors and qualified drive cycles before you can smog.

Reply to
Jeff Strickland

12-15 drive cycles will shut off the light and clear the code.. (reset the evap monitor)
Reply to
clare

corrected. How can I reset the light without disconnecting the battery or using the diagnostic tool?

I know I can reset it with a code reader. Was hoping there was a way to do it with a jumper instead of disconnecting the battery.

Reply to
Guv Bob

Thanks Tom.

FYI, I ran across this bluetooth adapter to read codes with Android phones.....

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NLQAHS

Reply to
Guv Bob

I just gave you the instructiona above. The evap monitor will reset itself after a number of drive cycles. I beleive on the Aerostar it is between 10 and 15.

Reply to
clare

That looks pretty cool! Let us know how it works for you. I just might get one and hold my old Innova as a backup :-) I just "updated" my 2002 Escape to a 2014 Escape, so I might as well up update my code reader, too LOL!!

Reply to
SC Tom

I know I can reset it with a code reader. Was hoping there was a way to do it with a jumper instead of disconnecting the battery.

+++JStrickland++++++++++++++ No, there is not. Whether you do a hard reset with a scan tool, disconnect the battery (which the specification says is not supposed to reset) or simply drive the vehicle until the computer recognizes that the condition has been cured, it still takes the same number of drive cycles to set the readiness monitors to ready, or complete (which is the proper term).
Reply to
Jeff Strickland

been corrected. How can I reset the light without disconnecting the battery or using the diagnostic tool?

to do it with a jumper instead of disconnecting the battery.

I googled it and don't understand what a drive cycle is.

Reply to
Guv Bob

On Thu, 6 Mar 2014 14:34:36 -0800, "Guv Bob" wrote:

For the evap monitor it is cold starts with gas between 1/4 and 3/4 full. Less than 1/4, more than 3/4, will NOT reset the monitor. The engine and air temperatures must be within a couple degrees - as stated below.....

This is the "full" OBD2 drive cycle for Ford vehicles:

Step One: How to Prepare Your Vehicle Have the fuel tank between 30 and 70 percent full. Some systems, especially the EVAP system, need to have a specific level of fuel in order for the tests to be trusted. If the fuel tank is near empty or completely full, many of the basic tests will not run at all.

The vehicle must also have a good alternator and a strong battery. If you have to occasionally jump-start your vehicle, all of the memory from the powertrain control module (PCM) is erased, which includes the data that accurately tracks the results from various stages of the Drive Cycle. Also, if the battery is weak or undercharged, some of the most important tests will never run.

The vehicle must sit overnight, or for at least eight hours, in an environment that is less than 90° F. The engine temperature needs to match the air temperature in order to establish an accurate baseline for the testing. If the outside temperature is over 90° F, the fuel is too volatile and the EVAP system won't even try to run its tests, though some of the other emissions systems may run their tests. The keys must be out of the ignition and all of the doors must be closed while the vehicle sits over night because many of the onboard computers "boot up" when the keys are in the ignition. Also, many of the onboard computers still run until all of the doors are closed after the vehicle is shut off and the keys are removed.

Step Two: The Cold Start Start the vehicle and let it idle for two to three minutes in Park or Neutral. While it is idling, turn on the head lights, heater/defroster, and rear defroster for a three to five minute warm-up phase. Let the idle speed settle down to near the normal speed. Next, put the vehicle in gear and drive through city streets at about

25 mph. Go up to about 35 to 40 mph a few times before slowing down to stop. Don't roll through the stop; be sure the car is really stopped, just like you learned in driving school. Accelerate from each stop in a normal fashion?not overly conservative, but not like you are competing in a drag race either.

Step Three: A Short Freeway Trip After the vehicle has been cold started and driven for a few miles on city streets, the next step is to take it on a short freeway trip.

Enter the freeway on-ramp and allow enough room with respect to other vehicles so that you can do a 1/2 to 3/4 throttle acceleration up to freeway speed.

When you have accelerated up to around 60 mph and have safely merged into the flow of traffic, stay in the slow lane and maintain a steady speed of 55 to 60 mph for a minimum of five miles. Please use the cruise control to help you maintain speed. Find a nice, long off ramp to exit from the freeway. As you exit, take your foot off of the accelerator and let the vehicle coast down until it stops under its own power as you complete your exit from the freeway. Do not use the foot brake and do not shift gears until the very end of this "coast down" phase.

Step Four: More City Driving After you have completed the freeway trip, drive through the city streets for a repeat of the second part of Step Two.

Go up to about 35 to 40 mph a few times and then maintain a city speed of 25 mph before slowing down to stop. Again, don't roll through the stop and make sure to accelerate normally. Pull in to a parking place and let the engine idle for one to two minutes and then shut it off.

Step Five: Wave your Readiness Monitors Checked and Verified Drive your vehicle to your regular shop and have them re-check your readiness monitors, present codes, and pending codes. They should do this as a courtesy and for free.

If all of your monitors are "ready" and there are no present or pending codes, then your vehicle has been properly repaired and is ready for an emissions inspection and for normal driving.

If the monitors are not "ready" :

Step One: Double Check Vehicle Preparation Have the fuel tank between 30 and 70 percent full. Some systems, especially the EVAP system, need to have a specific level of fuel in order for the tests to be trusted. If the fuel tank is near empty or completely full, many of the basic tests will not run at all.

The vehicle must also have a good alternator and a strong battery. If you have to occasionally jump-start your vehicle, all of the memory from the powertrain control module (PCM) is erased, which includes the data that accurately tracks the results from various stages of the Drive Cycle. Also, if the battery is weak or undercharged, some of the most important tests will never run.

The vehicle must sit overnight, or for at least eight hours, in an environment that is less than 90° F. The engine temperature needs to match the air temperature in order to establish an accurate baseline for the testing. If the outside temperature is over 90° F, the fuel is too volatile and the EVAP system won't even try to run its tests, though some of the other emissions systems may run their tests. The keys must be out of the ignition and all of the doors must be closed while the vehicle sits over night because many of the onboard computers "boot up" when the keys are in the ignition. Also, many of the onboard computers still run until all of the doors are closed after the vehicle is shut off and the keys are removed.

Step Two: Repeat the Basic Drive Cycle Follow the Basic Drive Cycle steps faithfully. Make sure to keep the speed on the freeway between 55 and 60 mph for a minimum of five miles. Please use the cruise control to help you maintain speed and stay in the right lane for safety reasons.

Step Three: Take Note of Which Drive Cycle Monitor(s) Did Not Complete

Drive your vehicle to your regular shop and have them re-check your readiness monitors, present codes, and pending codes. They should do this as a courtesy and for free.

If all of your monitors are "ready" and there are no present or pending codes, then your vehicle has been properly repaired and is ready for an emissions inspection and for normal driving.

If your monitors are not "ready," then take note of them.

If a Check Engine Light illuminated and/or a pending code was set, the repair shop who worked on your vehicle did something wrong. They need to re-do their work, for no additional charge, unless a totally new and unforeseen trouble code has occurred.

Step Four: Prioritize Which Monitor to Address In most cases, the three continuous monitors will complete. These constantly monitor the sensors, the fuel mixture, and the occurrence of misfires. If the oxygen sensor heater monitor is not ready, check to see how many other monitors are not ready. If the oxygen sensor and catalyst monitors are also not ready, the culprit is most likely a weak battery. If your battery is more than four years old, replace it and re-run the Drive Cycle. Even though your car may start just fine, the PCM is hypersensitive to the slightest glitch in the battery. It will suspend the Drive Cycle if it is not happy with any aspect of battery performance and/or charging system performance. If only the oxygen sensor heater monitor is not ready, but the oxygen sensor monitor, catalyst monitor, EVAP monitor, secondary air system (if applicable), and EGR system (if applicable) are ready, then, in almost all cases, the heater monitor will eventually set and be "ready." When a heater circuit is getting old, it can be one of the last monitors to pass. But if the oxygen sensor and catalyst monitor are ready, then the heater has to be working or the other two monitors would fail and set codes. If the EVAP monitor is not ready, verify that your fuel cap is tight and the level of fuel is between 1/4 and 3/4 full. If all the other monitors are ready, then do a couple more "cold" starts. If the EVAP monitor still has not passed or set a pending or present code, then take your vehicle to a shop that employs technicians who are familiar with the Mode 6 Diagnosis.

If none of the other monitors set, you should also take your vehicle to a shop that truly understands Mode 6 Diagnosis.

Reply to
clare

has been corrected. How can I reset the light without disconnecting the battery or using the diagnostic tool?

way to do it with a jumper instead of disconnecting the battery.

Thanks. I saw that also.

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What a crock to have to go thru this nonsense just to reset an error flag. This is a good example of how some companies hire programmers with no real world experience. There's a flaw in the original program, so instead of correcting it, make the user jump through hoops. I will give it a try but was hoping for something quick.

Reply to
Guv Bob

Thanks. I saw that also.

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What a crock to have to go thru this nonsense just to reset an error flag. This is a good example of how some companies hire programmers with no real world experience. There's a flaw in the original program, so instead of correcting it, make the user jump through hoops. I will give it a try but was hoping for something quick.

++++++++++++++++++++++++++ I don't understand what the problem is. Your car told you that it was sick, you made it better, now it has to have some ice cream and watch movies for a couple of days. No big deal.

There is no "crock" here, and the system appears to be working according to the design specifications.

The reason there is nothing quick is because people would go to the smog station with the Check Engine light on, do the "something quick" that you are looking for and put the car in for the inspection. To prevent this sort of fraudulent behavior, the people that came up with the OBD II specification designed in a Drive Cycle requirement that demands the car actually work right before it is ready to be submitted to the smog check station.

Reply to
Jeff Strickland

Now, since MOST jurisdictions allow ONE monitor to fail and still pass the smog test, you COULD reset the codes and get all the monitors except the evap set (can be done in less than 15 miles) andSTILL pass with a faulty evap system - but with your luck it would reset as you pull in for your test, and the light would come on - and you would fail. (assuming you had an unresolved evap problem)

Used to be they did a cap check as part of the test - but not any more.

Reply to
clare

You are entirely right, except that they allow one or two monitors to not be complete and still let the test proceed. You said they allow one to fail, but they really allow one to be incomplete -- still running.

There is a subtle difference in a monitor that has failed, as you said, and is not complete yet. If the monitor has indeed failed, then it is compete and did not pass the self-tests that you described. If the self tests have not finished running, that is the condition for which the vehicle can still be submitted for testing.

I'm not sure about the allowance of one or two monitors still running. When I had this issue, they let me test with two still running, but I get a mixed explanation as to whether they still allow two or only one, or if they allow two for cars that are older and one for cars that are not so old. But, you are also correct here, most (if not all) jurisdictions that test for smog do not require that all monitors be finished running the tests.

Reply to
Jeff Strickland

disconnecting

In my case, no smog check is needed until next year. I would like to know right away if I have fixed the problem without buying a code reader, borrowing one from the auto parts store or starting/stopping and driving all over town, hoping the gas level and all the other parameters are within the test specs.

Reply to
Guv Bob

In my case, no smog check is needed until next year. I would like to know right away if I have fixed the problem without buying a code reader, borrowing one from the auto parts store or starting/stopping and driving all over town, hoping the gas level and all the other parameters are within the test specs.

+++++++++++++++++++++++++++++++

It matters not when the next inspection is due, the specification is that the car complete specific conditions known as a drive cycle, and it must complete them multiple times, before a detected malfunction will clear itself.

If the check engine light is on for the evaporative emissions control system, then why do uyou care if the light is on. It will go away by itself, and you have an entire year for it to do that. Just drive your car normally and the fault will clear by itself if you have diagnosed the symptoms correctly and then taken the proper steps to remedy the malfunction.

You cannot know right away because if you could then you could also cheat the smog test machine by clearing the code and the check engine light, and then submitting the car for a smog test.

Be patient, Grasshopper.

Reply to
Jeff Strickland

I meant fail to complete - or set - sorry. No sensor can fail.

Some places allow one monitor to fail to complete, some two.

Reply to
clare

If the light went out, you fixed the problem. Buying a code reader won't fix anything - all it will tell you is if the monitor has set or not. By next year, the monitor WILL have set if all that was wrong was the loose gas cap - or the check engine light will come back on. If you put the light out with the scanner it will come back on when the monitor completes, if there is still a problem.

If the light went out on it's own, the monitor has reset, because it cannot do the test untill it is "ready"- or set.

Reply to
clare

The light has not gone out, that's what he wants to have happen, but he does not want to use a scan tool to force the light out, he just wants it to go out by itself.

He stated that the gas cap was the problem, but he never gave us the code for what the computer thinks the problem is.

Reply to
Jeff Strickland

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