CK5
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Voltage draw help
- Thread starter 454Sub
- Start date
ok after reading this i can tell you guys know what your talking about. now i just bought a 84 k5 and after the first alt went out on me and a battery i have found out that my alt wont turn on to charge my bat im not real good with wiring but the ground is good and so is my alt so please help me out.
Folks here that are more familiar with K5s might know, but how many wires are going to the alt.?
If its a single wire, those have to be turned faster than a minimum rpm before they light off.
After that, they will charge down to idle until you turn the truck off, then have to see the minimum speed again.
If the PO put a reduced pulley kit on, you may have to rev the engine once to get it to start charging.
Otherwise, if you have a remote voltage regulator, it may be bad. Or, if you have an idiot light on the dash, it has to be working for that model to charge.
A bad wire or blown bulb would do it.
You need a good voltmeter to figure out what is going on. Don't even depend on the dash unit.
Unless your battery ground is hooked directly to the alt bracket, try a jumper cable from the negative post to the alt frame just to be sure.
Lots of possibilities, grab a good meter, and let us know what you see.
454Sub
5/8 ton status
On the ALT question. It has 2 plug ins. One is a flat 2 wire connector. and one bolts on the back and is the charging lug. First things first, use a volt meter and see if the ALT is putting 12 or more volts at the charging lug. If it is your wire is broken or corroded and not giving the battery any volts. If it is not putting anything out, the flat 2 wire connector is to blame. The ALT needs an "exciter" wire to get it to kick on below 2500ish RPM. Actually I believe either Hot Rod or Car Craft has an excellent article on this a month or 2 back. You should be able to look it up on their website, its on a readers ride 70 Mustang Boss or some Mustang similar.
And no, the test light method is not exact. It does a very wide range job, vs a very specific reading on a meter. Problem is I havnt been able to locate a correct fuse for mine as of yet.
And on the Ohms setting, you can test for a direct short somewhere in the harness with it correct? But my question is what is the regular un shorted Ohms across the battery cables vs cables or wires with a short?
And relays have 4 to 5 connections. One for signal, 1 ground, 1 12vt constant fused, 1/2 power out to .... So technically, wouldnt the relay automatically click as soon as power is applied through the system, as it is supplied all the time with a constant 12vt source?
And no, the test light method is not exact. It does a very wide range job, vs a very specific reading on a meter. Problem is I havnt been able to locate a correct fuse for mine as of yet.
And on the Ohms setting, you can test for a direct short somewhere in the harness with it correct? But my question is what is the regular un shorted Ohms across the battery cables vs cables or wires with a short?
And relays have 4 to 5 connections. One for signal, 1 ground, 1 12vt constant fused, 1/2 power out to .... So technically, wouldnt the relay automatically click as soon as power is applied through the system, as it is supplied all the time with a constant 12vt source?
See what happens when i'm tired. Thanks for correcting me Fordum.
No prob. We have all been there. I didn't give it much thought at first.
But then, I happened to see another post where you had some misspellings and dropped letters, and started getting worried.
I flashed back on Rob's posts and was wondering if you were about to have problems.
Then I got smart and checked your post time, and realized 12:16 AM was a clue..................
Normally on a relay (like fuel pump) the "signal" wire does not have 12V going to it until it is "switched on" by something, such as the ECM, ignition switch, etc.
Realistically they are two separate circuits...one side is the "power" side, one is the switching side. Power side always has 12V going to it, but until 12V is applied to the switch side of the relay, it doesn't actually operate.
454Sub
5/8 ton status
Thats what I thought. So no matter what, they should click once as power hits the system. As in I hook the battery up. My fans both run off a single switch powering 2 relays. I checked the switch and its reading 0 across the board when the switch is powered down, so its not draining there. One thing that might be getting me is the headlight wiring. The headlight switch is constantly powered, and it might be letting a little power leak past the switch and trying to turn the relays on. They seem like they are pretty warm to the touch even though they are never on except when I turn the headlights on.
That lug on the altenator where the thick red cable attaches is "hot" all the time,just like the positive battery post,so anything connected to that will have power all the time...and could be draining the battery till its dead...a radio's memory will do just that over time.....................................................................................................With the truck running you should have 12V at the large output terminal at the altenator,and at BOTH of the wires in the 2 pronged plug too--if only one wire has 12V there ,it wont energize the feild coils and let it put current out...the wire thats either tan or white comes from the ignition switch and sends 12V to the feild coils,the other wire on that plug thats usually red,is a constant 12V hot one...a quick way to test to see if the altenator charges is to hold a screwdriver near the rear bearing in the housing,if it is charging,there will be a strong magnetic pull--but be careful not to short the output terminal to ground while doing this test!...if it tests "good" on a bench test,then its most likely your not getting 12V to both small wires on the 2 pronged plug...
Should be pretty simple to test (even with test light): if there is any voltage going to the headlight relays on the switch side, you have a problem.
454Sub
5/8 ton status
No voltage to either set of relays. There is 4 in all. I thought they were the probably originally as they were the last thing installed. They just have 12vt going to them. All the signal wires are dead till I activate them via switch or headlight switch.
I going to just pull them fuses and see if that helps. I wouldnt figure powering 4 relays would kill the battery so fast. But we shall see. With all the headlight/tail light/horn and dimmer fuses pulled, it seems to hover around 1 amp on the 10amp fused scale on the meter. It seems to almost vary a lil bit.
I going to just pull them fuses and see if that helps. I wouldnt figure powering 4 relays would kill the battery so fast. But we shall see. With all the headlight/tail light/horn and dimmer fuses pulled, it seems to hover around 1 amp on the 10amp fused scale on the meter. It seems to almost vary a lil bit.
The relays should only click when something tries to turn them on. So the headlight relays should only click when you turn on the headlights (with the headlight switch off they should do nothing as you connect/disconnect the battery). They should only be warm when the headlights are on. This is the normal power dissipated by the coil resistance. If the relay is warm, it's "on". You may have wired them up backwards, swapping the NO/NC contacts (although some automotive relays don't have NC contacts). This implies that the fixed side of the coil should also be swapped from 12V to GND.
If the relay coil is connected to 12V and the stock headlight wire, it will energize the relay the whole time the truck is off (finding a suitable ground path through the headlights) and/or the headlights are off. It would only be de-energized when the headlight switch is on. This would explain your dead batteries 100%.
A switch like your headlight switch can not "leak" power unless there is a foreign object in it or it's the lighted type. It's function is to mechanically break the circuit.
454Sub
5/8 ton status
Well its not going through the relays, all 4 are cold and the battery is hooked up and all the fuses are in. Its getting close to drinking time so I plan on letting it sit till tomorrow and going through it one by one again.
