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Ok, I was messing with my car one day and I unplugged the PCM (Powertrain Control Module). Well I figured out I shouldn't have done that and plugged it back in. Now instead of my car reading miles it's reading something else (I have no idea what it is reading now, but it was at 100,000 miles and now it says 589,000), and I'm sure I havn't been that far in this car. So if anyone has any ideas please help me out!


Thanks.  

i don't know what caused it.. but i bet it's really going to be hard on the resale value... what ever you do.. don't throw out any printed invoices for oil changes or car repairs that show the mileage...  all of them not just one or two....

its a huge fine to tamper with the speedo...  take it to  the DMV with your receipts and a carfax. if you have them.,.. they will put a corrected mileage sticker on your door jam..   .

i had a friend who wanted a mustang rag top stick shift... he found one.. ... the trunk lock was punched out.. the intake was misinstalled. and leaking vacuum big time...  the headers had broken and  the exhaust was dragging under the car... the drivers door hinges were really loose... the key was really worn...    the guy said it had 118K miles..  i told him it had 218k miles.. and low balled him... he went and payed for a car fax... the car did have 218K miles.. instead of selling it to us.. he got his money back at the auction... they had misstated the actual mileage to him...     he was so angry that the auction would lie to him...

so don't think anybody is going to tell you how to turn the speedo back ...  

Well I'm not even exactly sure that it's reading miles. So is there any way to change how the car reads distance?  

if it read 100K miles.. it would read 160,934.4 kilometers...

in removing the connector with the battery connected.. you might have just sent the pcm into speed of light...  

live with it..    or disconnect the battery again..   leave it off overnight..  maybe it will correct itself...  

If the PCM is to be unhooked the battery should be disconnected first, otherwise it could set off a voltage spike that may cause it to go into what I call "Stupid mode"  

I like Wayne's last idea, Unhook the battery overnight and see what happens after a drive cycle the next day.

Good Luck

One other question, what the hell were you doing unhooking the PCM, did you have a reason?  

Well my friend and I aren't what you would call "car guys" and he told me that was an external amp. What an idiot I know....

Anyway, we were trying to hook up a radio and wire it into the car so he said to unplug that, such a dumb idea when I look back on it...."My external amp?!?!?" Anyway, I think the PCM got unplugged while the battery was still on, and it happened to be the only time I actually forgot to unplug it while I was messing with my radio.

So then we unplugged the radio, again, I think the battery was still plugged in. Then when we figured out we forgot to buy something for the radio, I tried plugging the radio back in and it got LOCKED.

Someone was also telling me that its the radio that got screwed up because that has the security system in it? Anyway, if this unplug the battery thing doesn't work I'm taking it to the dealers on Friday.  

Well, once I was young and did something very similar to what you guys did, makes me laugh thinking back about it. You described it perfectly though " What an idiot " lol...

Oh well, live and learn. You'll have to bring it back in to unlock the radio anyway so no biggy there. Let us know what you find ok?  

Will do, and the radio doesn't need to be unlocked now because we figured out how to put the new one in. But I'll see what they say about the odometer and get back to you.  

Well they said that they have never heard of such a thing and that I would need to start with a new odometer cluster. They told me the bill was going to be around $500.  

Ouch, sounds like a dealership don't it?

Well apparently by unhooking the battery it didn't help did it?

I'm not sure where I'd go with that, I'd probably check on a used unit from a bone yard before I'd let them get into my nickers, and that may not fix it anyway. Wouldn't that be a kick in the butt, spend that kind of money and still have no speedo. I'll do a little research and let you know, sometimes the system can be what they call "Reflashed" It kind of resets everything back to factory settings. Be back soon!  

there is a problem....    reflashing the computer does not reset the mileage...  the ecm is also connected to the speedo head...


drive the car...    show off how many miles you have gotten out of it... must be a really great car to go that far and still run on the original motor and transmission...

i hope that you get a tax break for mileage drive very year...   and that you get payed per mile driven...

when someone asks you how you went so far... tell them you were abducted by a UFO and the wheels were outside of the force field and spun all the way to the back side of the moon and back...  they will have to think that must be what happened.. no other way to explain it.. unless they read this thread....

drive it into a car max dealer ship and ask for a price quote like you are going to sell it to them...  hehehehe

when the guys at the oil change place say something... about the huge difference in mileage... say yea.. i know  i went a little farther than the recommended 3000 miles.. but it was an emergency ...   be sure to use your best poker face when you do it...


drive it in the dealer ship and ask how much for the maintance check... ... when they stick their head in the window to get the mileage.. be sure to be watching...

i love a good practical joke...  i once told a nightshift cab driver who had fallen asleep in my driveway.. that he was in north san diego...  but he was actually in los angeles... he looked really lost... and his fair who was asleep woke up to find him saying that he did not know how they had gotten to north san diego... but he would drive her back at no charge... took her a few  minutes to make him understand that he was still in los angeles and where she wanted to be...  sometimes a practical joke works too well...  

Good call Wayne, I think the moon landing would be a little bit of a stretch.

Vollium , here's what the book says. IPC being the instrument Panel cluster.
"The IPC displays the vehicle mileage and trip mileage as determined by the BCM (Body Computer)  The BCM calculates the mileage based on the vehicle speed signal circuit from the PCM. The odometer will display 'error' if an internal IPC memory failure is detected or there is a loss of class 2 communication."

I just thought it was strange, you don't have an IPC error message do ya? Which leads me to believe that the cluster is probably ok. The information isn't getting to the IPC from the BCM. Like I said, a reprogram may take care of it, It's just my thought.  

Yeah, I think that the cluster is okay too, and I'm not willing to gamble $500 just to see if we're right or wrong. I'll go to some smaller shops and call around to see if they can take a look at it and give me my best bet. But those dealerships will get ya. They charged me $100 just to plug my car into a diagnostics. It was $100 for "labor." Must be hard to plug stuff in for them dealership folk, lol. Thanks for the help though, I'll keep researching and see what I can do.  

Thanks wayne it helped me too

mecarz