Recently put in a new alternator after the old one died on me (after an hour drive), but now the car wont shut off using the ignition. I hooked up the alt exactly like the last but something isnt right. I've noticed the lack of a diode or light on the path and I did not wire this car. Previous owner converted to 12v using EZ wire harness. I've owned the car little over a month w/o this problem until now. How do I know if its the missing diode, ignition, or wiring? The battery is new and I just charged it after the alt gave out. Kind of new to all this, seen a ton on the net, and now I'm lost lol Im running a LT1 small block from a '71 C-10 in a '50 Chevy Deluxe Appreciate any help
It could be possible the old alt was not working properly and issue never happened. I would go either the diode route or better the warning light. Either is simple to do. Good luck Ray
I've seen this problem when installing alternators on forklifts. If you use an ignition wire to connect to the regulator, it can feed power to the ignition with the key off. Use the accessory terminal on the ignition switch to connect to the regulator or install a cube relay controlled by the accessory terminal to open the circuit. Another way is to get an alternator that only has one wire that connects directly to the battery.
Another way is to run that wire to the unused post(outer post) on your starter solenoid. I had the same problem when I converted my car over. Wired it this way and haven't had a problem yet. Question...how did you get it engine to quit? Did ya pull the coil wire? I did that before, won't do it again for a while
Thanks everyone! I will try some of these ideas starting with the diode/light. I've gone through all the wiring and I think thats what threw me off. Is the following arrangement right? Nothing connects directly to ignition switch. 1 - comes from solenoid which I plan to replace with larger gauge 2 - labeled "alt power" connects to fuse box 3 - excitor wire connects to fuse box Hillbilly - I removed battery connections and the car turned off within 30 seconds
Had this problem on a 65 ford wagon does it have a ford starter relay if so try changing it worked for me we also changed alt and ignition switch in dash worked for me give it a try
Is the new one exact replacement for the old alternator? Could you have possible put an externally regulated alternator on? As I see you made reference to 1971 LT1 engine. If you check the thread suggested above, the #1 terminal on back of alternator is fed through diode, or idiot light, from ignition, check that. Did you do anything else to car? I had an electric fan, that was direct feed from ignition, that had enough momentum aftr key off, that it would back feed the ignition circuit until it stopped rotating. Once I put that on switched relay, engine wouldn't run on. Just some more suggestions to look into.
in line diode works great! had a few forklifts and tractors do this and pulled the diodes out of old alt. and wired one in and stopped issue.
I believe the alt you show in the picture is one which requires an external regulator. If you want to make the wiring simple, use an internally regulated alt.
This problem cost me a $$$$ engine. Alternator backfeeding to fuel pumps - engine overheated due to coolant loss - would not shut off either with ignition key or master cut out switch. Painless Performance Products has a kit to eliminate this condition....
After trying to add an idiot light last night, I realized the auto store gave me the wrong alternator. I needed an internal regulated one but they gave me an external by mistake. So I went back to the auto store to exchange it and they still tried to give me the wrong one. After showing them the difference I finally got the right one. A little rewiring and problem solved!! Looks like the previous owner used an external alternator and incorrect wiring, resulting in an early alt/battery death lol Thanks for helping me get back on the road, everyone
Question...how did you get it engine to quit? Did ya pull the coil wire? I did that before, won't do it again for a while [/QUOTE] I had the same problem as the OP when I switched from an externally regulated alternator to a 12 SI ... "smothered" it with a shop towel on the carburetor. Grabbing the coil wire didn't seem like a good idea at the time. As others have reported, I fixed the problem by adding a diode to the system and lived happily ever after....
If you keep the alternator you have and use a regulator. The regulator will have terminals F 2 3 4 F goes to f on the alt. 2 goes to the r on the alt. hook 3&4 together go to the ignition switch. After market regulators aren't very good.
" I believe the alt you show in the picture is one which requires an external regulator. If you want to make the wiring simple, use an internally regulated alt." "If the picture is the alternator your using it wont work, that an old GM externial regulated alternator. You probaly need the GM internial regulated,or is that how they riged it. " "Is the new one exact replacement for the old alternator? Could you have possible put an externally regulated alternator on? As I see you made reference to 1971 LT1 engine. " >>>After trying to add an idiot light last night, I realized the auto store gave me the wrong alternator. I needed an internal regulated one but they gave me an external by mistake. So I went back to the auto store to exchange it and they still tried to give me the wrong one. After showing them the difference I finally got the right one. A little rewiring and problem solved!!<<< I'm glad we could help!!!!!
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