New Alternator - Strange Problem
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New User
Joined: Nov 2002
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From: Cedar Hill USA
New Alternator - Strange Problem
I have a 1990 Bronco with a 351W and AOD. I recently had a 3G 130amp alternator installed. Since then I am having a strange problem. When ever the truck is running and I shift into reverse the rpms drop and either fluctuate like it's trying to find the correct idle or the truck dies. This happens no matter if i shift into reverse from Park, Neutral or Drive. As soon as I feel the transmission engage it occurs. Vaccum leak maybe?. What would replacing the alternator have to do with this? Thanks for any suggestions.
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New User
Joined: Nov 2002
Posts: 9
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From: Cedar Hill USA
New Alternator - Strange Problem
The guy at the alternator shop said it wasn't necessary to replace the cable. I am still not clear as to what this has to do with the engine dying when I shift into reverse. Have you had this problem?
Freshman User
Joined: Jan 2003
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New Alternator - Strange Problem
It really is necessary.. it puts more of a load on the system than it can handle with the stock wiring... you need a heavier guage wire to run to the battery. I know from experience, I fried an alternator and could have done some other damage electrical wise but I got lucky... so it is possible.. Did the problem start right after you put the alternator on? Does it only do it in reverse? I will get a link for you to read
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New User
Joined: Nov 2002
Posts: 9
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From: Cedar Hill USA
New Alternator - Strange Problem
Yes it started up only after the alternator was installed. It only happens when I shift into reverse and then only after i feel that little lurch when the transmission engages in reverse. It doesn't matter if I shift from Park, Neutral or Drive into Reverse, the rpms drop, fluctuate and most of the time the engine dies.
Post Fiend
Joined: Nov 2002
Posts: 9,987
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From: Memphis, TN
New Alternator - Strange Problem
The alternator never puts out more than the truck needs, so the stock cable is fine until you put more load on it than the stock cable can handle, which is probably 140A. I've been using a 130A alternator for 4 years with the stock wire and a 9000lb winch with no problems.
The most likely cause of the engine dying is the IAC, so pull the codes.
The most likely cause of the engine dying is the IAC, so pull the codes.
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New User
Joined: Nov 2002
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From: Cedar Hill USA
New Alternator - Strange Problem
Thanks Steve. I will pull the codes this weekend. I am wondering though why it only dies when I put it in reverse and not drive?
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Freshman User
Joined: Jan 2003
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New Alternator - Strange Problem
oh your right, it started after he changed alternators but that doesn't have anything to do with it.... read this when you get the chance.. its on a mustang but same principle
3g alt upgrade
3g alt upgrade
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Postmaster
Joined: Jan 2003
Posts: 4,417
Likes: 3
From: Durham, NC
New Alternator - Strange Problem
The motor torques in a different direction in reverse. I would say
you have a maginal contact at an electrical connector that is
getting stressed when the motor torques in reverse..
you have a maginal contact at an electrical connector that is
getting stressed when the motor torques in reverse..
Hotshot
Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
New Alternator - Strange Problem
What is your idle speed at when your shifting into reverse. The line pressure goes up when shifting into reverse and if your idle is to low then it can cause your motor to die. When was the last time the tranny was serviced. might be something to consider to.
later
later