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  #1  
Old 05-15-2009, 10:14 AM
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How to Reset the PCM

I have a 2003 F150 and I think I need to reset my PCM. I don't think the disconnecting the negative battery terminal is doing the trick. I think I need to have a mechanic use a scan tool to reset the PCM. Does this sound logical? I don't think the common folk can buy a scan tool that will do a PCM and crankshaft sensor relearn without having alot of cash. Please let me know if there are any scan tools that will do these kind of features that are not real expensive. I don't know if they exist or not. Please help. I'm in need of some help.

Thanks,

Brian
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  #2  
Old 05-15-2009, 10:33 AM
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As far as I know, a scan tool does not reset, it just reads the codes. You disconnect the battery and turn on the lights for about 30 minutes to reset the PCM. You may be thinking of a PCM reflash. That involves loading a new program into it.
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  #3  
Old 05-15-2009, 11:32 AM
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If you are trying to relearn throttle trim, disconnecting the battery will do the trick.

On the 97-03 MY, when you hooked it back up, you needed to start the truck, let it idle for ~ 2 min, then take it for 2 drive cycles. The truck needs at least 1/2 tank of fuel in it.
The drive cycle is driving it as you normally will ( i.e. if you are heavy on the throttle off the line, drive it that way, no need to beat on it ), pull away, and you need to sustain over 46 mph at least 2 times in the drive cycle, then back down, stop, and repeat. So it is a case of city ( with stop ), freeway, city ( with stop ) and freeway.

Not sure what you are trying to do with a PCM and crankshaft sensor relearn. What is the problem you are trying to cure ?
BTW : the crankshaft sensor does not perform any learning, it either works or doesn't.
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  #4  
Old 05-15-2009, 07:58 PM
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There's no real need to screw with the battery cables.

Every Ford with an OBDII system that I've looked at so far has a single fuse that, when removed for 10-15 minutes, will reset the PCM's KAM without messing up the radio or the clock.
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  #5  
Old 05-16-2009, 03:08 AM
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What are you trying to accomplish, exactly?

Fords don't have to "learn" the CPS like GMs, so there's no "relearn" procedure.

According to Ford, the KAM will go volatile within 5 min of losing KAPWR.
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  #6  
Old 05-16-2009, 08:26 AM
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When the PCM KAM is reset, all the data tables are reset to baseline values for variables such as idle control, shift parameters, and fuel trims. The PCM then has to go into its adaptive control strategy in order to "re-learn" its best operating values.

This is noted in the owner's manual regarding operation after the battery has been replaced (at least).

Most people reset the PCM in order to clear codes. It is also recommended to do so whenever replacing a sensor or component that directly controls PCM strategies such as O2 sensors, IAC valves, TPS sensors and the like.
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  #7  
Old 05-16-2009, 10:21 PM
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I had to replace my engine a few months ago because I run a supercharger and was out racing and got a little lean and bam my motor went out. A couple of months ago I noticed the gauges in my truck take about 8 seconds to start working and my check engine light does come on for a second when I turn on the ignition. Also, I was low on gas one day and I noticed my low fuel gauge doesn't work either. So basically my gauges don't start working for 8 seconds after my ignition is turned on and my low fuel gauge and check engine light doesn't work. Also, I have noticed the P0315 code has showed up. The crankcase sensor isn't fun at all the replace. I know the a/c condensor and a few other parts have to be taken off to get to it. Would my truck run bad if my crankcase sensor was bad? My truck seems to be running pretty good actually. I didn't know if I needed to reset my PCM or do I just need to get my crankcase sensor replaced and then see what in the heck is wrong with my gauges. I took my instrument cluster out the other day and checked all my bulbs and everything was fine so I'm somewhat at a lost. You have to love having all these sensors on these newer trucks. Any advise you have is greatly appreciated.

Thanks,

Brian
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  #8  
Old 05-16-2009, 10:29 PM
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Gauges acting up is quite often an indicator that the battery is getting weak. These trucks take a lot of power to function properly.
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  #9  
Old 05-16-2009, 11:09 PM
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The battery is not too old but I sure will get it checked. Doesn't mean my battery hasn't lost some of it's power. I guess it can still run the lights at night and start all the time but still be short on power?

Brian
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  #10  
Old 05-16-2009, 11:13 PM
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Quote:
Originally Posted by bixbystx View Post
The battery is not too old but I sure will get it checked. Doesn't mean my battery hasn't lost some of it's power. I guess it can still run the lights at night and start all the time but still be short on power?

Brian
Yes. But if you have a newer battery, probably not it, but it's easy to have it checked, to make sure.
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  #11  
Old 05-17-2009, 01:45 AM
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There is no "crankcase sensor". CKP is CranKshaft Position sensor. Have you looked at the sensor & tone ring for physical damage? You don't have to remove the compressor (and certainly not the condensor) to pull the sensor - just remove the belt & loosen the compressor bolts so it slides down an inch. Pull the sensor out & use a penlight to examine the tone ring teeth.

I was mistaken earlier - there is a relearn procedure. Find an empty stretch of road, get the truck up to ~65mph & drop the throttle until you get down to 35, then repeat 2x. If that doesn't clear the code, take it to a pro for further diagnosis.

The only effect that this code has is that the misfire monitor is disabled. So if you have misfires, no code will be set. But a damaged sensor &/or tone ring can cause misfires, and misfires can damage the engine, trans, catalysts... And whatever caused the damage to the sensor/tone ring needs to be identified, as well.
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Last edited by Steve83; 05-17-2009 at 01:48 AM.
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Old 05-17-2009, 01:45 AM


 
 
 
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