I've got a 198x toyota (something from the 80's) that I just droped a new engine into. I'm having problems with the charging circuit on. It will charge to 11.71 volts while running and if put under load (like turning on lights or wipers) it will drop off. I have a new alternator, new voltage regulator, and new battery. I am assuming that it must be a wiring problem of some sort as I figure the alternator is not getting triggered when it is supposed to be.
The engine is from a 1983, and the truck is mostly a 1980
Your alternater is NOT charging. Your voltage reading of 11.7 volts indicates your battery is discharging. A fully charged battery will read around 12.6 volts.
I have a new
You need a wiring diagram for your year truck and a multimeter. Check all the charging system wires for continuity and proper voltage.
First of all, 11.71 volts is not charging at all. A charged 12 vdc battery should be over 12.6 vdc without the alternator on. with the engine running the voltage should read anywhere from 13 to 14.5 vdc, depending on the state of the battery. I would put the battery on a good charger and get it fully charged. I.E., 13.2 vdc or so fresh off of the charger. Then see if the alternator is working or not.
I had an '87 that did not charge right when I bought it. We found out later that there was two different alternators for that year and the previous owner had put in the wrong one. Both had internal regulators.
You need to make sure you have ground straps from the battery to the engine and the body. The alternator is mounted to the engine, so it should ground to the block, but the block has to be grounded to the battery. It is possible tyo have too many ground points, but it is far easier to have too few. Lack of proper grounding creates what is effectively an open loop that is very unstable. Obvioulsy, the engine will ev entually be grounded through the various casings and other components, but this ground is very poor even on a good day. What you really need is a heavy guage wire from the battery to the engine, and another from the engine to the body. Some will say that a ground from both the engine and body to the frame is also a good strategy because there are body mounted components that are physically grounded to the frame.
Since you just replaced the motor, I have to wonder if the ground straps were attached. If you have to attach ground straps, I suggest stranded
10-guage wire (as opposed to solid wire). You can go as heavy as you want, and I recall the battery cables are something like 4-guage -- where lower guage numbers equate to heavier weight wire. Heavier is better, and good connections are a must. Clean metal is far better than painted surfaces.
One other thing I can think of is a defective alternator. You can remove this component easily enough, and they will test it at the auto parts store for free.
I had the same problem with my '85 truck. Turns out I got a bad rebuilt alternator. The second one worked fine. Take the "new" alternator back to where you got it and have them test it.
ya I already got a new alternator to replace the first new alternator with no difference (never had it tested although i think i might take it by wally world cuz i hear they test them) (I have a good multi meter (fluke 289)) and will attempt to follow through the wiring diagram. I think the ground to the battery might help so i'll try and rig one of those up on tomaro or saturday depending when I have time off work.
well i have added another ground strap from battery to engine mount, and i've replaced the voltage regulator. I knoticed that the charge lamp relay is non-existant could this have anything to do with it?
I have the same problem. Did you find anything? I have tried all these too. I havent tried the other altenator though. I do have an adaptor fotr it. Let me know when you solve the problem. Thanks, Scott
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