Will removing positive battery cable reset computer? | Ford Explorer Forums - Serious Explorations

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Will removing positive battery cable reset computer?

beavis195

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City, State
Sammamish, WA and Provo, UT
Year, Model & Trim Level
94 XLT 4 door
My Negative cable is toast, I'm real scared to remove it because I'm scared I'll crack the clamp in half. No money for new one ($59 from Ford) so if I remove the positive cable for 10 minutes, will it reset my computer?
Thanks
 



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I believe the only way to properly reset the computer is by either junmping the test terminals(I don't know how) or by using a code reader.
 






Any disconect of the battery should do the trick.
 






Disconnecting the battery cables from the battery will do no harm to anything. As far as resetting the computer, I've never noticed any difference in anything after disconnecting the battery and then hooking it up again, no matter how long I've had it disconnected. I've heard the old trick about disconnecting the battery for 10 minutes or so to reset the computer, but I've honestly never noticed any change in anything when I do it, so I wouldn't worry about hurting anything.

As far as paying Ford $59, I'm sure any auto parts store could sell you a suitable replacement for much less.

I'd go ahead and replace it, for safety reasons. You wouldn't want the cable clamp to break when you're out in the middle of nowhere and leave you stranded.
 






no, just doing the positive cable will not reset the computer; youre gonna have to do the negative one - im sure you can get a cheaper cable at napa or pep boys or something, any place is cheaper than ford. disconnect the neg cable for about 30 minutes or so (while its disconnected, turn on the lights for a sec to kinda drain the system out) then hook it back up, and let the truck idle for about 5 min, then if you want, you can drive it around a little while.
 






On the subject of battery cables:
Does anyone know why many diag test say to remove the "neg" terminal from the battery before testing?

I also know that vintage car owners put those quick disconnect battery terminals on the negative side of the battery. These usually have a green dial you turn to break and the connnect the battery. They sell them at all the car shows.
Using the negative side always puzzled me. The postive side would seem to make more sense and better eliminate any case of shorting or shocks.
Can anyone shed some light?
 






Originally posted by tbomb
no, just doing the positive cable will not reset the computer; youre gonna have to do the negative one

Huh? Why is this?
 






You can make and break the electrical circuit by negative or positive. Some of Ford's connections are done by constant power and just making and breaking a ground. It works the same both ways. If you'r electrical system has no ground it will act just the same as if it didn't have power. BTW. I asked my friend that is a mechanic for Ford and he said you can't reset the computer on the 95+ explorewrs by taking away the power for any length of time. He said that only worked on the earlier fox body mustang computers. He said but they were really non-sophisticated computers. He said the best way without taking it to Ford and paying them to put it on the computer is to sit there and turn your key on and off over 50 times. He said it's nota gaurantedd method but the only way that has ever worked for them.
 






If you have OBD I you can also do a little trick with the voltemeter that clears the computer. It's described in the Haynes Manual.
 






Really.Cool thanks. I will have to check thhat out and run it by him also and see what he says. Ford sent him to the school to program the computers and stuff so maybe he knows something new now.
 






Originally posted by MSTNGGUY88
. . .BTW. I asked my friend that is a mechanic for Ford and he said you can't reset the computer on the 95+ explorewrs by taking away the power for any length of time. He said that only worked on the earlier fox body mustang computers. He said but they were really non-sophisticated computers. He said the best way without taking it to Ford and paying them to put it on the computer is to sit there and turn your key on and off over 50 times. He said it's nota gaurantedd method but the only way that has ever worked for them.

Your friend is only partially correct. It depends on which computer he is talking about and what type of codes. If it is a hard failure code and the problem has been repaired, but the light takes a certain number of on/off cycles to clear, then yes disconnecting the battery WILL reset the computer. I've disconnected my IAC before while my engine was running. Checked the codes with my OBD-II scanner, leaving the code in memory. I then disconnected my battery. When I reconnected it and restarted my Explorer, the light was out and another read with my scanner revealed no codes found. The air-bag computer can not be reset by disconnecting the battery though. It takes 256 successful restarts with the code not present to reset. A Ford scanner will also clear it quicker.
 






Thanks. Mine was a problem with the fuel system and it didn't clear it with the key cycles. I never have had my light come on but that one time so I guess i'm lucky and haven't had to experience reseting the computer any. Thanks for clearing all that up though.
 






Originally posted by IgotTwo
On the subject of battery cables:
Does anyone know why many diag test say to remove the "neg" terminal from the battery before testing?

I

There is less chance of screwing something up if you remove the negative cable first. You should always do this whenever possible. If you try to remove the positive cable first, you run the risk of letting the wrench touch the frame and welding it there, or worse yet blowing up the battery or causing a fire. .:nono:

Disconnecting the battery will reset the computer memory for the opertaing parameters (richness, idle, driving params), but will not reset any error codes stored in the memory. Usually when you reconnect it, it will idle rough for a few minutes, and then the computer takes about 10 miles or so to figure out the "optimal" settings to get the best overall compromise on performance depending on how you drive those 10 miles.
 






Thanks for the replies guys. I'll go to NAPA monday and get a new cable. The Explorer cable is kind of weird with 3 wires coming off it and 1 looks like it's a smaller guage.
 






Originally posted by mahieber
Disconnecting the battery will reset the computer memory for the opertaing parameters (richness, idle, driving params), but will not reset any error codes stored in the memory.

Yes it will, depending on the code. If your PCM stores a code for your gas cap being loose or MAF or IAC failure (such as when you disconnect them while your engine is running), if your problem has been fixed, disconnecting the battery will clear the code. These are the three I've tried, I am certain there are others. Some codes require a certain number of successful key on/key off cycles to clear the code from the PCM once the problem has been fixed. Disconnecting the battery will clear it immediately. I've done that twice while on the road. The first time my Check Engine light came on when traveling across the US. After the usual pop-the-hood-and-look-around, I drove for the next day and half with the light still on. When I got to New Mexico, I was tired of looking at it. I pulled that battery cable at a rest stop. When I restarted it, the light was gone and I didn't see it for another year and a half. The next time my Check Engine light came on, I had just left work on a cold day. About 1/2 mile from work, my light came on. I pulled in to a gas station and shut off my Explorer. Did the usual look around and restarte it. The light was still on. when I got home I pulled the battery cable again. The light stayed out for about 10 days before it came back on. That was when I bought my OBD-II scanner. I used it to determine that my lower intake manifold o-rings were leaking un-metered air into my cylinders.
 






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