Reprogramming the PCM

[Jake's Dad]

To reset, don't we just pull the negative battery terminal for like 40 minutes or so?? Dealer wanted to charge me an hour labor to reprogram the PCM. I said "no thanks". Did I do the right thing here??

JD

 

[CobraXP]

Usually leaving the negative off for 20 minutes or longer will clear the computer and you should be good.

 

[Jake's Dad]

Cool, thanks. I figure they wanted to flash the PCM, but I dont think that it is really necessary. Anybody have input?

jd

 

[410Fortune]

Well re-flashing the PCM and reseting it's memory are two totally different things. If your PCM needed to be re-flashed you should ask the dealer why.

reseting the computers memory only takes a few seconds with the - battery cable disconnected. When you do this your computer thinks the truck is brand new and goes into a default mode, and then starts to re-learn the signals from the various sensors. You want to do this anytime you change a sensor, clean a sensor, or make any performance modifications.

Reflashing the PCM is actually downloading a whole new program to the computer and changing setting to it. This is only done by the dealer on later model trucks, I believe there were a few re-calls by Ford that required re-flashing of the PCM, also they do this to calibrate the speedometer, etc...

 

[Robert]

Ford issued a recall about a year ago for Explorers that came with the top speed cut-offin the PCM incorrectly programmed for 4.10 axles. On those vehicles it was possible to exceed the top speed rating of the tires. The fix was to re-flash the PCM. That is probably what he wanted to do. I would find out why he wanted to re-flash it though. Think about letting them do it once you have their explanation. If your Explorer is running fine now, the chances are that it won't run any better if it gets reflashed. Sometimes it can feel like they detuned it when they re-flash it. On my '97 SOHC I did have the dealer reflash mine due to a hesitation problem that occurs on the SOHC when accelerating from a dead stop. It fixed the problem I wanted fixed and didn't introduce any new ones.

 

[Jake's Dad]

Well, the tech didn't give me any explicit reason why. It was under warranty through Gaurdian (kinda sux), and I think they wanted to take all measures since they knew there was a warranty (soak 'em). Then I find out that no sensors are covered under the warranty. He pulled up the recall list on my vin and it said that nothing needed to be done. I think I should pass for now....

JD

 

[Big Bear Bob]

So if I wanted my 98 Explorers speedo to read corroectly while running 31" tires all I have to do is disconnect the battery? What about the alarm, and keyless entry? Do i lose that info or does it have a trickle battery of it's own?

 

[yob_yeknom]

No, the truck won't relearn what size tires are on it. You would have to have it reprogrammed for that. Your alarm system will be fine.

 

[Big Bear Bob]

yob_yeknom
Thanks wishful thinking on my part, but to be honest it doesn't look like the speedo is off by much but it would be nice to be sure though


Thanks again

 

[Apten]

JD, if you give me the 4 digit code on your EEC, I can tell you what they would reflash it to.

sometimes dealers even reflash to the same program. It doesn't really fix anything, but some think it does. If your car ran fine, then developed a problem after time it's probably not due to the EEC.

Also, the quick way to reset is just unplug the computer... it's instant.

Brian

 

[Big Poppa]

The dealer is probably talking about the relearning drive you are supposed to do after you unhook your battery. The procedure is detailed in your manual. Sounds almost impossible to do though- unless you have a closed track or something.
Let me know if you need the info.
(Mine is a '96 V8)

Anyone have any thoughts on if you should do this or not. I never heard of this or did it w/ my '91, but that is a diff. computer.

 

[Viro Holliday]

I am looking for information on reprogramming a 96 Explorer PCM. Here's the reason. The Tranny and Xfer case both went out. I have a 97 Explorer I use for parts. The 97 was manufactured in November so it has the 98 accouterments installed factory. When I replaced the two driveline parts, the 97 tranny which has the exact same casting numbers is missing a speed sensor on the front shaft at the bell housing, the transfer case is missing a speed sensor on the rear output shaft. Mechanically it is running sound but for these issue I'm having: 1. The tranny is having trouble knowing when to change gears. It can be manipulated with throttle but changes at higher rpm. 2. The speedo and cruise control do not work. These speed sensors on the 96 were replaced with a single speed sensor on the rear differential on the 98's. The sensor is on both models just the 96 uses it for ABS only and the 98 uses the sensor for everything. Can I reprogram the PCM to accept the updated tranny and xfer case that are now missing the two redundant sensors? I tried swapping PCM's but the vehicle would not start. Maybe an issue with the security computer, unsure. Anyone have an idea?