Big power drain in electrical system when headlights or heater fan is turned on

[Can30Diesel]

Hey guys,

I have been living with an intermittent yet slowly getting more constant issue with my truck. Here are the symptoms..

- Almost always after starting my truck for the first time in a given day and randomly on subsequent starts when I turn the lights on or turn the heater fan on, all electric power cuts out for just a second then comes back. At times its enough to cause the truck to stall and usually around that time the radio forgets all its settings.

- Randomly when I go to start my truck, I turn the key and nothing happens.. well everything electrical shuts off like it would normally while turning the key to start but the starter doesn't engage. I can turn the key off and on to start over and over and get the same result. Sometimes when I hold the key to the start position long enough the starter finally engages, and other times turning the key off then back to start over about 3 or 4 times it will cause the truck to start normally.

What I have done so far..

- I have checked and cleaned my two main grounds. they are good and clean.
- The issue persists with a new alternator and a new starter.
- All power connection points are clean, as are both battery posts on both batteries.
- Main ground cables are new. Main positive battery cables are original and have seen better days but they are clean and free of corrosion.

I have a feeling I have some bad ground somewhere or maybe there is some corrosion in the main battery cables I have not found yet. One way or another I have a major power draw on the circuit that the alternator initially can't keep up with.

I have had thoughts that it might be the headlight switch as I have read about those shorting out.
I have also thought it might be the relay/switch in the steering column that the key actuates might be wearing out.

I'll keep troubleshooting, however just putting this out there.. anyone ran into this before? Would any of these be enough to cause these symptoms? My truck was originally a farm truck rescue so anything is possible..

Thanks!

 

[laserjock]

Do the batteries seem weak or does it turn over normally when it decides to turn over? It sounds like a loose connection somewhere. Are all the things affected Key "on" circuits?


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[cpdenton]

Sure does sound like a problem with the wire that provides power to the fuse boxes in the truck. On my 92, there is a wire from the passenger side battery to the fender solenoid, and from there, another wire that provides all the power to the truck. Maybe if you are losing power to everything, the voltage regulator is turning off also.

 

[franklin2]

Yes, you said you checked all power connections, but did you check over there at the fender mounted solenoid. That's where all the power originates from to power the truck. There are bunch of smaller wires with fusible links in that location.

 

[Can30Diesel]

Do the batteries seem weak or does it turn over normally when it decides to turn over? It sounds like a loose connection somewhere. Are all the things affected Key "on" circuits?


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The batteries have all kinds of starting power when it finally does kick in. All "key on" circuits seem affected.

Sure does sound like a problem with the wire that provides power to the fuse boxes in the truck. On my 92, there is a wire from the passenger side battery to the fender solenoid, and from there, another wire that provides all the power to the truck. Maybe if you are losing power to everything, the voltage regulator is turning off also.

Yes, you said you checked all power connections, but did you check over there at the fender mounted solenoid. That's where all the power originates from to power the truck. There are bunch of smaller wires with fusible links in that location.

Thats where I am going to be looking today.

Thanks for all the replies, I will let you know how things progress.

 

[FordGuy100]

You should probably change out the ignition switch for good measure.

 

[riotwarrior]

I'd be dropping the column down and investigating the the main switch that key actuates and checking it out for shorts and so forth.

The KEY pun not intended is holding key down or switching on off a few times. I'd say that the switch is out of adjustment myself two 5/16 bolts IIRC...but eh...could be wrong

Try the switch is my best edumacated WAG

 

[wildman7798]

You say the "primary positive cables" are original - even with clean or new lugs the corrosion could have run up the wire a considerable distance - sometimes several feet or more. If there is any bared insulation on the primary cables where the lugs attach it could be a good place to check. You will see the powder or green on the copper. I have stripped back a foot or more of insulation on what I believed was a solid primary cable only to find it was badly corroded under the cloak of cover.

 

[Can30Diesel]

You say the "primary positive cables" are original - even with clean or new lugs the corrosion could have run up the wire a considerable distance - sometimes several feet or more. If there is any bared insulation on the primary cables where the lugs attach it could be a good place to check. You will see the powder or green on the copper. I have stripped back a foot or more of insulation on what I believed was a solid primary cable only to find it was badly corroded under the cloak of cover.

Another good point. Some additional information..

- These batteries are about 4 years old.
- If I charge them up all the way, then turn the key to on without starting the truck, I cannot replicate my issue.
- If I charge them up all the way, the truck doesn't seem to have the same no activity when the ignition is turned to start.
- When charged all the way, I run a volt meter to the passenger side battery, I go from 12.4V to a hair above 9V while cranking.
- When the truck is running, I have 14.4V on the battery at idle. If I turn everything (stereo with subs cranked, high beams, off road lights) on then I go down to about 13.5-13.8v at idle.
- If the batteries are fully charged, then the truck fires up no problem at all all the time.

Seeing as how these batteries have gone through 2 failed alternators and 3 years of playing stereos while camping, I have a feeling they might be packing it in. But whats stopping me from just replacing them is how random my problem is. I'll get to the point where I am sure its the batteries then the problems all go away for a couple months.

 

[wildman7798]

Hey guys,

I have been living with an intermittent yet slowly getting more constant issue with my truck. Here are the symptoms..

- Almost always after starting my truck for the first time in a given day and randomly on subsequent starts when I turn the lights on or turn the heater fan on, all electric power cuts out for just a second then comes back. At times its enough to cause the truck to stall and usually around that time the radio forgets all its settings.

- Randomly when I go to start my truck, I turn the key and nothing happens.. well everything electrical shuts off like it would normally while turning the key to start but the starter doesn't engage. I can turn the key off and on to start over and over and get the same result. Sometimes when I hold the key to the start position long enough the starter finally engages, and other times turning the key off then back to start over about 3 or 4 times it will cause the truck to start normally.

Based on this - and coupled with your most recent response I do not believe it is the batteries. While they may be showing signs of not recovering from discharge like they used to and have some cells that may be on the verge of giving up I believe the problem is still going to be current flow related or possibly elctro-mechanical (switch, solenoid, ect.)

My best guess is a flow/corrosion problem. You show the numbers on your meter that one would expect to see like the 12.4 charged and the 13.5-13.8 running. What we can't see is what happens when the demand for input current is called for, such as trying to crank. It sounds to me like high input impedence, which can be caused by anything in the path of the primary from lugs, to cable, to the starter armature and brushes themselves. Then you can't exclude the other switching components in the system like the solenoids, starter switch and wires going to them that route the primary power.

Corrosion can cause such intermittent problems like you are seeing. If the lugs on the positive cables are the cheap "2 bolt and clamp down the wire type" I would pull the wire off the lugs and slit the insulation up a little ways and look for the tell green or powder. If they are a factory molded lug/cable you can usually bend the cable away from the lug enough to get a look under the insulation, I would do the same with the ring lug cables between the 2 batteries and the ring lug cable at the solenoid on the inner fender. If you find excessive corrosion in those areas I would look at changing the cables before I did anything else. Since the "ground cables" are all relatively new and lugs clean you can probably rule them out. One other thing, I always use a good terminal cleaner but sometimes the cable lugs because they seem to use a lower quality lead than the actual battery lugs. I will take a pocket knife and peal a layer or two of lead off to get to the fresh stuff. Maximum current flow in both charge and discharge is imperative.

 

[Can30Diesel]

I have the factory style positive battery cable.

A while back I had myself convinced it was the positive battery cables I priced out replacing it with a new cable (building one) and it was about $100 here. Considering what was left of the old ground cables when I first started working on the truck, corrosion of the main positive cable assembly definitely makes more sense then the batteries at this point. I'll probably go down that road and see where it takes me.

Thanks for all the help guys. I'll keep you all updated as things progress!

 

[riotwarrior]

Hey...don't forget to mention in all of this YOUR NON stock Alternator in the mix rofl...I still suspect ign switch not fully shutting systems down and not fully starting...makes me wonder...If switch is tempermental it could cause drain on batteries etc.

 

[Can30Diesel]

My non stock alternator is charging just fine Al!

I agree with the ignition switch idea, especially since its probably the original switch. Is there any way to test them?

I have a feeling I have a few things contributing to the situation.

 

[riotwarrior]

My non stock alternator is charging just fine Al!

I am aware of that based on the info you provided

I agree with the ignition switch idea, especially since its probably the original switch. Is there any way to test them?

I have a feeling I have a few things contributing to the situation.

Testing them..it seems to be working..that is given..it also as I said seeming to maybe be out of adjustment.

they just slide up down the column a wee bit in oval holes. Drop the column or go to a pick a part and drop one of theirs..then learn how it works and grab the part if you like and have it incase yours is worn out.