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Batteries goes toes ups.

Nessmuk

Nessmuk

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Location
East Amazonian polar region
Ok, long winded intro warning...
I have two, red top batteries. They are mounted in the bed, in a plastic trunk. I have 4-0 cable to them. I had the batteries tested for a bad cell at advance.
I have dual, cs144 Alts. Both newer remans.
I have a 5 year old starter and solenoid.
I have a newish glow plug relay.
The rest of the trucks electric is isolated by a solenoid that connects only when the key is on.
Except for two circuits, which have no drain on them.
When it sits, it dies. Two days, maybe three.
How do I test the Alts for shorts in them?
How about the starter and glow plug relays?
How much draw is normal at rest from an alternator?
I figure I can unbolt the glow plug relay and test from it to ground.
Is it possible that the battery cables are leaking through the insulation and how do I test for that?
 
Charge both batteries. Disconnect batteries from each other. (Take the grounds off both batteries at the terminals.) Leave unhooked and test them again in 3 days to see if they are both still up. 1 bad battery (bad/shorted cell) will pull the other one down. A failing battery can have a surface charge that will pass a quick test but be dead a day later. If you didn't unhook the battery from the other one during the test the results are worthless. Note: Hot weather shortens the life of all batteries.

Again always disconnect the ground cables from both batteries first!

Use just one battery for current leaks and only test on the ground side. If you drop a ground cable "who cares?" as all it can hit is a ground. Drop a positive cable with the other battery hooked up and you start welding, sparking, wires catch fire including remote ground wires, and can explode a battery from the high current short.

Post up the current measurement from one battery with the other one disconnected. Leave the meter hooked up for 5 min and test again in case there is a computer that shuts off after a delay. Your wiring may not be how you think it is with the disconnect switch if it's leaving alternators hooked up, but, I am not there to see how it was done.

Replace batteries in pairs unless the pair is less than 6 months old and holding "new" voltage. varies with weather and damage done from bad battery.

Dome lights are known to come on from a bad switch in the middle of a "cold" night. Glove box light, map lights, mirror lights all need a check...
 
GM actually made a shim for the door switch. You could get it color matched to your dash. In really cold weather all that plastic shrinks. Also I was told to wait for 15 minutes for the PCM to go to sleep.
 
My truck doesn't do pcms or courtesy lights. Didn't have a power outlet when I got it either. It's an ex army pickup, no frills at all. I redid a lot of wiring on it. Mostly got rid of blackout lifts, ice testing port, glow plug army specific stuff. If it's anything, it's got to be Batts, Alts, Starter, Glow plugs related. There isn't much more left other than the ignition switch and a few OEM fuses. I've had the fuse box out and cleaned too. Even the light switch only has power if the keys on.
 
Nessmuk said:
I suspect alternator or battery as most likely.
Click to expand...

Then test for that. IMO you have a bad battery pulling the other one down. But with trons you have to see the problem to fix it or it gets expensive without results. This is where the current tests tell you where the power is going.
 
Unhooking the Batts sounds like a good idea.
Any idea how to test the alternators?
I've got a multimeter coming that has a diode test function. Don't know how to use it. Might have to do a search...
 
Red tops are not what they used to be . What truck is this ? Square body ?
 
I would use one battery and test for current draw on the battery ground post. Then test each charge terminal of the alternator for current draw. If the alternator is flowing current from the charge terminal engine off the diodes in it all need to be changed.

Hint: disconnect battery ground, hook up meter to alternator between alternator charge ring terminal wire and stud, make sure it isn't shorted and then touch the ground post on the battery with the battery ground cable. Look for current reading.

To be clear the above does not apply to 1 wire alternators that ONLY have a charge terminal connected.
 
I'm not running any one wires. Ones got 3: sense, light, excite, the other those and tach.
I'm waiting on the new multimeter for now.
So, test from the output on the alt, to the charging lead. What of the sense, excite and light leads, should they have any draw on or voyage from them?
 
Are you talking about the diodes in the alts or the 24V system ?
 
Nessmuk said:
I'm not running any one wires. Ones got 3: sense, light, excite, the other those and tach.
I'm waiting on the new multimeter for now.
So, test from the output on the alt, to the charging lead. What of the sense, excite and light leads, should they have any draw on or voyage from them?
Click to expand...

With key off the only voltage should be the charge wire and no current when you break and measure current on the charge connection.

Key off: Measure the alternator plug - should be 0v. If not you have a wiring problem. Voltage on the alternator pins IMO should also be 0v.
 
Glove what??? We don't have no drinking glove lights!
I did add footwell lights recently, and map LEDs under my switch panel. Guess I'm turning sissy. My truck has a fancy remote starter where all you do is sit inside and turn a key! Power assist brakes with a dual chamber master cylinder! Power assisted steering! A transmission that shifts itself! Remote, inside activated turn signals! Self heating interior with window defrosting! Electric horns and lighting!
Even safety features like safety glass! A padded dash! A collapsing steering column and anti flail chest steering wheel! Seat belts!
It even has a security system as easy as pushing down two buttons!
 
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