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Electrical Discharge - Update 3/7/09 - Problem Solved !

Lunatic

Lunatic

1/2 ton status
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Jul 27, 2008
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Location
Ft Hood, Texas
Okay brotherhood, time to pick thy brain. I hope somebody can shed some light on this.

I have an electrical problem.

Two weeks ago, on a Tuesday, I got the Jimmy inspected (state insp), no problems present at all. By the end of that week..... I had lost my headlights, my horn, and (insignificant but noted) my cigaretter lighter. I may have lost more which I havent noticed yet - IDK.

By the end of that weekend, I killed my battery dead.

I went to OReilly's on Sunday and picked up a new 94 amp alternator and a new battery (Im in the process of replacing alot of things and these were on the list anyway).

I drive 10 minutes to work and home every day. I noticed the voltage gage in my dash dropping by the end of last week and became concerned. This was no longer a bad alternator or battery - But an actual problem. This past Sunday night - I stopped at the same OReillys for an IR grinder. When I came back out and tried to leave, it took a dump.

Being that I was already there, I pulled the alternator and battery, with a blessing of "Pull whatever tool you need off the shelf." I swapped the alternator (again) and the battery was charged in shop. While it was charging, we tested the "bad" alternator to discover it was good. I kept the new alternator anyways though. :D

Tonight, knowing that the charge was already dropping since last Sunday, I took the Jimmy to Lowes, with trailer in tow, to grab some sheetrock, 2x4s, and insulation rolls. By the time I made it home, many red lights later - It was in the red, under 8vdc. I decided to leave it running while I unloaded the trailer, as to not kill the Jimmy and leave the entire driveway blocked (trailer in one lane and Jimmy blocking the other).

By the time I finished with curbing the trailer, an OReilly's trip was evident. I barely got it parked in the drive when it tried to stall. I parked it, jumped in my DD and off I went for a charge and maybe some more ideas.

Status: electrical drain with no apparent charge retention.

Whats New: Alternator, Battery, Steering Pump (not related), Fuel Pump (not related), Battery Cables, alternator two prong connector.

Whats Checked: Checked passenger side engine harness for frays - Only found connector wiring frayed. Battery ground on the alternator mount, and on the front grill cleaned. Engine grounding braid intact, but contact surfaces unknown (Its also to the firewall, not the frame ?), aftermarket HID headlights are physically disconnected (HD wire harness waiting to be installed after a solution to this problem presents itself), alternator and battery voltages checked with fluke (OFF - Alt stud = 12.86vdc, battery = 12.86vdc, 2 prong connector 0vdc <> RUNNING - Alt stud = 12.5vdc, battery = 12.6vdc, 2 prong connector - white = 9.94vdc, red = 0vdc)


350/700r4/208



I believe thats everything in a shell..... Ask questions for clarification, drop ideas.... Im calling a rally to my aid....

Thanks !




Troy B
Ft Hood, TX
 
Last edited:
i mean not to sound stupid or anything but have you checked things with a voltmeter? You know the alts good, and you got a battery drain, sure the battery is actually being charged? That or you got some massive drain. Im not that knowledgable but im just throwing the obvious out there. Im sure poking around with a voltmeter for awhile will find something..
 
I guess I should have put that in the "checked" description huh ?

Yes, I have probed the alternator and battery already. I wish it were so simple. But this is turning into something gremlin like - I hate gremlins :D


Thanks for pointing out the obvious - Its as important as what hasnt been found yet - We can now take it off the list of possibilities. I'll hit it again tomorrow night after getting back from OR's so I have a fresh test result from the fresh battery, and then post the results above.

From whats already been tested etc - The massive drain seems to be the problem - But where is it hiding....Hmm



Troy B
Ft Hood, TX
 
Im sure somebody whos good with electrical will chime in soon. Im sure a drain that massive cant go unfound for long
 
Sounds like the alternator is not being energized. Do you have 12V going from the + side of the battery to the large + connection on the alternator. The big terminal on the alt Should have 12+ volts even with key off.
 
Have you used a voltmeter ON the battery with the truck running? Ignore what your truck gauge says. If a voltmeter shows the charging system is working, then you do have a pretty massive drain.

If something is draining the battery, with the help of a testlight, you can probably narrow it down to a specific circuit.
 
whit the engine running, connect the fluke on the battery and check the voltage
should be close to 14v if 12v or less the alt is not charging(the alt checked ok on the bench but not in ur truck)if that is the case use a test light(not the fluke).
the treaded stud on the back should have 12v(light in test light on) all the time--- the red wire on the 2 prong connector should have 12v(test light on) all the time too---- the brown one should have 12v(test light on) whit ign switch on engine not running and nothing(test light off) whit engine running.
if there a problem on the brown wire here a quick fix to see if evry thing is ok

stop engine---put the clamp end of the test light to bat+ and the pointy end in the connetor brown wire(the connector IS still conected to the alt)the light should glow---
start the engine---the light should go out(sometime u need to rev the engine a bit),if it is out check the battery voltage should be close to 14v

hope it help a bit

keep us posted!!
 
Your alternator should compensate for any load imparted to it.

Have you ascertained the voltemeter is reading close to what the alternator is putting out?

When you see voltage drop at the gauge, is the alternator output lug (which is all you care about) still putting out 13+V?

A drain large enough for the alternator to not be able to cope would kill it in short order. They can't run at max output for long before they die.
 
Time to start pulling fuses and find out what circuit is drawing current while the truck is shut down.

Use the fluke to "replace" each fuse while in the DC amp mode, shouldn't have much current passing through anything but fuses that protect your radio's time keeping circuit (if so equipped), clocks or anything else that happens to run all the time, regardless of if your truck is powered up or not.

You'll probably find most are reading next to no current, and suddenly one will provide a significant reading, figure out what is attached to that circuit and find out which device is drawing current. If it isn't an end device, you need to start looking for short circuits.
 
Check for chasis grounds

Check wires for grounding issues

Do you have aftermarket gauges? My autometer tach was on a constant on circuit and it would slow drain my battery.

Look for anything out of the ordinary.
 
I think I have it......

Heres the missing information - also added to the original post:

alternator and battery voltages checked with fluke (OFF - Alt stud = 12.86vdc, battery = 12.86vdc, 2 prong connector 0vdc <> RUNNING - Alt stud = 12.5vdc, battery = 12.6vdc, 2 prong connector - white = 9.94vdc, red = 0vdc)


Yeah, gages are for reference, not precision. Its hard not to point it out though when I was stuck at a light in rush hour traffic after work.....And had nothing to do other than watch it drop some, sweat, move forward, watch it drop some more, sweat..some more, move forward, watch it drop.....lol


Okay, I took the starter to OR's this evening and it tested 'good'. The positive stud had a loose backing nut, which tightened up seemingly well - So, I came home with the same starter.

That wasnt my find of the evening though......

Something just doesnt seem right here. (And be sure to thank my wife for holding the wire in the first pic :bow:)

(pic #1)
5400862


After finding this on the starter wire harness, I carefully dissected the wire insulation away with an x-acto to find what I thought I saw - The wire is in two. This wire in particular, leads to the alternator 2 prong connector, red side. Where as I had a hot white side on the connector, the red side was dead, obviously. I believe this is the cause of my whole problem (what do you think ?)


So, what are the capsules in pic 2 below ? I need to fix this regardless of its relation to the problem. Might the numbers be a rating marker of some sort ?

(pic #2)
5400865




So, I thank everyone who has added their knowledge and suggestions to help resolve my problem. Tomorrow, I will pick up the necessary parts to get this wire back together, and post the results.


Thanks !



Troy B
Ft Hood, TX
 
Last edited:
Dabba said:
pictures are dead, save and upload em
Click to expand...

Probably a delay on the upload end...I backed em up with direct links above the pics



UPDATE:
According to Chilton......As printed.

"In addition to circuit breakers and fuses, the wiring harness incorporates fusible links to protect the wiring. Links are used rather than a fuse, in wiring circuits that are not normally fused, such as the ignition circuit. Fusible links are color coded red in the charging and load circuits to match the color of the circuits they protect. Each link is four gauges smaller than the cable it protects, and is marked on the insulation with the gauge size because the insulation makes it appear heavier than it really is.

The engine compartment has several fusible links. The same size wire with a special hypalon insulation must be used when replacing a fusible link.

The links are located in the following areas:
1. A molded splice at the starter solenoid Bat terminal, a 14 gauge red wire.
2. A 16 gauge red fusible link at the junction block to protect the unfused wiring of 12 gauage or larger wire. This link stops at the bulkhead connector.
3. The alternator warning light and field circuitry is protected by a 20 gauge red wire fusible link used in the battery feed to voltage regulator #3 terminal. The link is installed as a molded slice in the circuit at the junction box.
4. The ammeter circuit is protected by two 20 guage fusible links installed as molded splices in the circuit at the junction block and battery to starter circuit."
Click to expand...


At this point I am really thinking they are fusible links, and the numeric markings represent the sizes....14 and 16....


Can anyone confirm this ?

Thanks




Troy B
Ft Hood, TX
 
Last edited:
No, they melt, which means they break the connection in that wire. They act just like any other fuse.
 
That failed fusible link in particular prevented the alternator from getting the signal to start charging. The break wasn't discharging the battery, the engine was discharging the battery and the alternator was not charging.
 
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