1992 F150 Voltage Drop

[Kaajot]

Hi all-

So, the 1992 F150 now has a non-leaking, sealed, brand new 300-6 that fits its year. The transmission is from a 92-94 same style (E40D) F-150. We found broken pins in the transmission shifting connector and repaired with a new plug and repaired the broken pins by soldering new pins with new wire onto the existing wire bundle. I have a complete new pig tail on standby for any future shenanigans from RockAuto ($14) to donate pins, wires, or just solder the entire thing to the vehicle-side. I'm hoping the transmission-side receptacle repair is not needing attention for two to three more decades.

It shifts smooth while driving now and shifts at about where I expect it to all the way to Overdrive.

However, when parked and selecting a gear, the battery voltage still drops. It also drops when in gear or Neutral and I turn the wheel left or right. We just put a new power steering pump in because the old one was completely seized on the pulley, but I hear some complaining at the pump when I make these turns and the voltage drops considerably. I even did it about 4-6 times at the gas pump before shutting her off to fill up the truck and the voltage meter on the instrument cluster appeared to freeze/disengage permanently until I restarted the truck and it went back to the L on the Normal (about 14-15 voltes with alternator running). The stuck position was at the O in Normal, probably a 10.8-12v position.

Any ideas why this Voltage Drop continues to plague me? I've replaced 8 MAP sensors, but the pin that was corroded and broken supposedly went to the MAP sensor. I'll be severely pissed if I lose another MAP sensor within 500 miles.

Going after what Dusty said, I am continuing to suspect the Neutral Safety Switch and found this information about the old E40D NSS MLPS being inferior and needed to be upgraded to a 1995+ manufacture date and model.
https://www.usshift.com/e4od.shtml

If that's true, I'm going to bet I need a new NSS/MLPS anyway. Could its resistance from water corrosion be the cause of the spikes and be tied to the turning of the wheel drops as well? It makes sense that the drops when selecting gears would be tied to this component, but I'm not sure about why in any gear and stationary if I turn the wheel that the voltage also drops and actually becomes "stuck" in a minimal voltage from battery indication even though it looks like my alternator is kick'n it like a champ and keeping it charged.

Electrical gremlins are my bane still and I want to smite them all now that the mechanical aspects really should be fine. I'm probably due for a new alternator soon, but I don't think it's the cause of this persistent symptom and we've fixed the transmission electrical wiring harness connector problem (after finding it). Gotta be close to fixing this....


EDIT!

PS: I'll make an iphone video of these symptoms in motion from my cab and post it.

 

[dustybumpers]

Another common problem with battery in these OBS (old body style) trucks, the hot wires on the solenoid get corroded. Take them off, and sand them clean, put a dab of die electric grease on them, put them back. I think we already discussed the importance a while back of a motocraft solenoid, not cheap Chinese junk. Sorry rockauto dont sell them. Last I bought was this week from ebay from uhaul. They cost $8.95.
Normal cost for that solenoid is around $30



There is an adjustment on the mlps at the transmission. I recall a notch and a bar having to line up, but it's been a while
YouTube it


That adjustment is important it can cause all kinds of issues, and may be your problem. I'm on my phone, or I'd hit you a link. Sorry for that.

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[primetime]

To add to this. These trucks have a big fat (battery cable size) wire that is fed by two fusible links at the solenoid. It runs across the front of the truck over to the power distribution box. it has a ring terminal and bolts to the power distribution box. I would take that apart and scrub it up good.

Check your voltage drop on the charge wire between the alternator and the solenoid. Likewise with the wire that feeds the power distribution box.

If it was my truck I would get rid of the fusible links on the charge wire and power distribution wire and replace them with mega fuses. I would also upgrade the main charge wire.

But don`t forget your engine to frame, body, battery grounds. It`s a 28 year old truck and a 10 gauge wire between the engine and firewall doesn`t for instance, cost much to replace. Just saying.

And if you have reason to think the alternator needs replaced, don`t hesitate to put a voltage gauge on it with the truck at idle, in gear, with the wheels cranked and accesorys on to actually see what it`s doing. Both at the alternator and the solenoid. Check it at the power distribution box also.

 

[Kaajot]

Thanks PrimeTime and Dusty.

I'm gonna have to figure out power distribution box. Solenoid -- starter solenoid? I know that one.

Gonna do some more MLPS checking, Dusty, but that link basically covers that if it's not upgraded to a 1995+ MLPS (Neutral Safety Switch) that it's doomed to get water in it and corrode, so I just ordered the E4OD NSS for a 1995 Automatic E40D F150 off rock auto, WVE with 3 year warranty, 36K miles. It has an adapter to mate up with the older harness and water proof it. That's basically one of the take-away from the first link.

Second link I found covers more things that sound eerily familiar -- all things E40D Transmission Related. This link is pure gold. I've done the VSS in August on the side of the road, did improve some things.

https://www.ford-trucks.com/forums/904459-really-useful-writeup-on-dreaded-e4od-i-found.html

PrimeTime, will keep scrubbing the grounds and power cables, yep. We have replaced many of the fat battery cable grounds for the bat to frame, engine to frame, bellhouse to frame, etc. I found the rotted power solenoid to amp cabling (4 gauge) and repaired that, but gonna check my ground on the amp behind the bench seat because I'm getting feedback. It's either that or again, the alternator may have some damage in the AC/DC converter part of the unit. So gonna work on the wires and grounds, but may go for a new alternator after testing (need to figure out how to test). Another transmission symptom in the above link covers the alternator mini-converter component failing and shooting AC through DC wiring, causing the transmission symptoms and would also explain my speaker feedback. I always though I blew something in the amp when the ground came off, but maybe it shorted back to the alternator back in 2015 and I had no idea. But that's speculation, so just gonna start looking at wiring and continuity/resistance, voltage measuremets,etc.

 

[Kaajot]

And if you have reason to think the alternator needs replaced, don`t hesitate to put a voltage gauge on it with the truck at idle, in gear, with the wheels cranked and accesorys on to actually see what it`s doing. Both at the alternator and the solenoid. Check it at the power distribution box also.

This all makes sense, but power distribution box -- we talking the distributor? I'm not the best mechanic and I'm running out of things that I can think are the power distribution box. That 1992 F-150 bay without Air Con is a pretty empty bay compared to some trucks -- easier to work on, but don't know where the Distribution Box would be at this point and I know where most of the stuff is now in this gen/series and engine.

And, we've replaced at least most of the grounds. And I did find the corrosion at the starter solenoid for the amp power supply (audio amplifier). I'll take a look at the other hot wires -- mechanic likes to chase grounds, doesn't chase power for some reason and I found the last rotted power supply 4 gauge. There's a chance he's missed other rotted power lines to short out the truck when there are power draws.

Any idea which power supply line is affected when a power steering pump is put under load (ie moving left/right)? Not-turning, it's all good. But put an input in on the wheels and wherever that gear is turning, the sensor measuring the input gets some serious voltage drop to the point it off-lines the alternator or battery cable.

Or maybe the starter solenoid has just gone bad.... The more I think about that, maybe I need to test it (how?). I think I had a NAPA or WVE or motorcraft Solenoid installed. I know my F-700 has motorcraft installed, but unsure which one got put into the F-150 in the last 2 years.

 

[primetime]

The power distribution box is the fuse block on the drivers side inner fender. It`s the main power source for the whole truck. It get`s it`s power from the battery positive terminal on the starter solenoid. It has a little plastic cover on the fender side of it that slides up to expose the stud the main charge cable bolts to. Take it apart and clean it also.

Remember, the starter solenoid on the fender is just a relay. It`s only purpose is to send power to the starter mounted solenoid when activated, and to serve as a junction block for the battery positive wires to hook up to versus connecting somewhere else. By battery positive I mean the main charge wires coming from the alternator are bolted to the stud that the battery is hooked to, and the underhood fuse box is also connected to this same stud via fusible links.

Don`t overthink the starter solenoids(relay) purpose. If the connections are clean(shiny), tight, connected properly, and the truck starts like it`s supposed to, then it`s fine.

As for the voltage drop when turning. I reread your post but don`t recall seeing if this was only happening at idle, or doing when you rev it up and try to turn the wheels also. At a low idle an alternator isn`t turning very many RPMs therefore it isn`t putting out it`s max power. As you turn the wheels and put a load on the power steering pump it is further dragging down the engine RPM which in turn lowers the alternator output. See where I`m going here?

I do believe your truck has a 2G alternator (external fan), which didn`t put out that great. Ford came out with the 3G (internal fan) and one of the 3Gs benifits is more power at idle, hence why it`s such a popular swap for older trucks. That and the increased amperage.

2G alternators are also known for melting the charge wires connection at the alternator, which go to the starter solonoid battery positive, which feeds the the whole truck. Clear as mud? If not it`s my fault lol.

I`m not trying to lead you in different directions, just offering some stuff to check out/off your list.

 

[dustybumpers]

Pretty sure he has a 3g, I think his truck is a 94.
I never thought about the power center good call. And he is correct about turning at idle. Nature of the beast.

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[Kaajot]

Don`t overthink the starter solenoids(relay) purpose. If the connections are clean(shiny), tight, connected properly, and the truck starts like it`s supposed to, then it`s fine.

As for the voltage drop when turning. I reread your post but don`t recall seeing if this was only happening at idle, or doing when you rev it up and try to turn the wheels also. At a low idle an alternator isn`t turning very many RPMs therefore it isn`t putting out it`s max power. As you turn the wheels and put a load on the power steering pump it is further dragging down the engine RPM which in turn lowers the alternator output. See where I`m going here?

I do believe your truck has a 2G alternator (external fan), which didn`t put out that great. Ford came out with the 3G (internal fan) and one of the 3Gs benifits is more power at idle, hence why it`s such a popular swap for older trucks. That and the increased amperage.

2G alternators are also known for melting the charge wires connection at the alternator, which go to the starter solonoid battery positive, which feeds the the whole truck. Clear as mud? If not it`s my fault lol.

I`m not trying to lead you in different directions, just offering some stuff to check out/off your list.

So, the alternator was replaced by a reman in Arkansas in 2013. I don't know if I got a 2G or a 3G, but if I buy a new one from Advance, should it be a 3G? That's what I'm eyeing due to its warranty. Believe it's a good brand too, will check.

So they have Bosch Reman with 2 yr warranties, but if I go DriveWorks or CarQuest (electing CarQeust) it has limited lifetime warranty at Advance, so that's the one I believe since I should always be able to get to an Advance Auto Parts. It's an original casting, but 80 amp, slightly higher than the 65 and 75 amp offerings on other alternators for this generation F150 VIN Y.

https://shop.advanceautoparts.com/p...tor-7744-2an/20170227-P?searchTerm=alternator

And yep, I figured out what the Power Distribution Box was once I thought it over a bit. I've chased some relays to it, but they always looked good and had good continuity. I might want to look underneath and see if there's any corrosion on the backside of the PDB wiring.

Everything else, clear as mud.

 

[Kaajot]

Pretty sure he has a 3g, I think his truck is a 94.
I never thought about the power center good call. And he is correct about turning at idle. Nature of the beast.

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It's a 1992! I mentioned 1991-1994 earlier about the Neutral Safety Switch's first generation being defective (prone to water creeping in) and have bought a 1995 Neutral Safety Switch to replace since I'm 99% sure no one swapped it out on the donor transmission.

It's definitely low voltage drop at idle and lowering rpms where the shorting is noticeable. If you got the peddle to the metal it's not cutting out. There are times where in drive under a slow 15-20 mph and a good BUMP on a dirt road to the farm that I've had it cut out on me, making me think wiring short.

 

[Kaajot]

2G vs 3G Alternators

I do believe your truck has a 2G alternator (external fan), which didn`t put out that great. Ford came out with the 3G (internal fan) and one of the 3Gs benifits is more power at idle, hence why it`s such a popular swap for older trucks. That and the increased amperage.

2G alternators are also known for melting the charge wires connection at the alternator, which go to the starter solonoid battery positive, which feeds the the whole truck. Clear as mud? If not it`s my fault lol.

So, I found I'm probably using a 2G and found 3G available on a 1995 that has the same bolt pattern and higher amps (95!) They have 130 amps too, but the bolt pattern doesn't match (more vertical than L-shaped in the pin placements around the "circle" of the alternator center.

Here's a 1995 F-150 Alternator by ACDelco that explicitly states it's from the family Ford 3G Alternator production run.

https://www.rockauto.com/en/moreinfo.php?pk=3468387&cc=1414583&jsn=2393

Here's a 1995 F-150 Alternator by Bosch that I'm looking at from rock auto, lifetime -- will see if Advance carries it for ease of replacement.

https://www.rockauto.com/en/moreinfo.php?pk=501157&cc=1414583&jsn=2396



Here's a Remy from RockAuto on the 1992, lower amps but the bolt patterns, plugs, etc look the same. Will see if ANY of the alternators directly state they're 3G, but I don't think they do.

https://www.rockauto.com/en/moreinfo.php?pk=474310&cc=1122028&jsn=2260


Just scrubbed Rock Auto between the 1992 and 1995 models. Yep, 1992 alternators are all 2G or should be. They're not 3G for sure. 1995 at least has some that state their family and they're 3G

 

[Kaajot]

Also, like the Neutral Safety Switch, 1994 and below are 2G atlernators on Rock Auto.

Guess I'm buying a 1995 Alternator.

Also, if I ever buy another Gen 8/9 Truck, I'll be looking for a 1995 or 1996. ^_^ Apparently that's when Ford decided to get the bugs out of the original old body style trucks and made things run better in gen 9.

 

[dustybumpers]

91 was the last year for 2g. Like primetime said, lack of a fan on the alternator means it's a 3g.
Check the wires that plug into the alternator too. I had an issue on a 3g where the wires didnt seat properly, and it was hot or miss. They call it a 1 wire, but it takes 3.
1 from the solenoid bolted on. 2 in plug goes to alternator. 1 is green red. That is the key wire tells it to charge. Other wire comes out and back into alternater. That is usually white. That excites the diode.

If these are loose, or not making correct contact they will not work under load. You can get this piece on ebay for about $5 if you need to rewire. Solder and heat shrink, no butt splices please

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[dustybumpers]

Take a picture of your alternator please before you do anything. You dont just change from a 2g to a 3g. There is rewiring and buss fuses involved.
If indeed you have a 2g. I have no problem giving you a list of what you need, and how to do it including pictures. I have several here I have done with great results

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[Kaajot]

Take a picture of your alternator please before you do anything. You dont just change from a 2g to a 3g. There is rewiring and buss fuses involved.
If indeed you have a 2g. I have no problem giving you a list of what you need, and how to do it including pictures. I have several here I have done with great results

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Oh! Good to know.

I'll probably be in the shop next week doing a ground repair to the amp and working on the Neutral Safety Switch/MLPS, so I'll get some good tests done on alternator wiring, inspect the pins, etc and take some pictures of it.

The 750W amp is an extra draw, plus I have LED fog lights on the front ranch hands. Any extra power from a better alternator wouldn't be a bad thing, good to know there's a conversion process!

 

[dustybumpers]

As long as the lights are wired through relays they will draw very low voltage.

Remember. Fan behind belt=2g
No fan behind belt =3g
This is a 3g on my 94 that has belt issues

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[Kaajot]

As long as the lights are wired through relays they will draw very low voltage.

Remember. Fan behind belt=2g
No fan behind belt =3g
This is a 3g on my 94 that has belt issues

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Yeah, it's starter solenoid --> relay & in-line fuse that came with lights - -> led fog lights.

The amp however is starter solenoid --> In-line fuse wiring --> Amp --> Speakers. That's how it was depicted it should be wired.

Yep, I took a look at the pictures on rock auto and saw the ones that had fans and didn't have fans. Pretty easy to see (vented siding for fan airflow).

If I had a 2g that got replaced with a 3g in 2013, would the truck have still worked despite the shop doing any "modifications" to the truck to get the alternator in?

Also, I went looking at 1991 alternators on rock auto just to see the difference. I see a "Plastic fan" right behind the pulley. Got it. HOWEVER, there are some without the plastic fan that rock auto is still listing as 2g in both the 1991, 1992, and 1994 years. Is that possible, because that makes me think I still possibly have a 2g or my alternator was replaced haphazardly with a 3g and may be the reason I'm burning out my electronics over the long haul because I never had any modifications done to accomodate a 3g in a 2g wiring harness.

Either way, I think I want to go for the higher amp 1995 alternator that has the same bolt pattern and 3g stamp of approval. Will get better information on the alternator after I've done my grounding repair at the amp, wire checks on power, powder distribution box checks and added the newer style Neutral Safety Switch and completed MLPS adjustment/check.

 

[Kaajot]

Hey Dusty, what modifications are required to add a 3G Alternator if I am running on a 2G Alternator? We're suspecting the voltage regulator is out of wack (AC/DC issue I mentioned earlier causing a whirling hum sound in the speakers that grows louder with RPM). So I think I'm going to just put a new alternator in anyway -- if I have a 2G, what do I need to do?

And if I have a 3G, how do I just verify the wiring is not in 2G-format? Both are possibilities based on my knowledge of the truck and being the second owner since 2009. Same question, basically, but if they put a 3G in 2013 and it was originally a 2G, that would explain my electrical gremlins.

 

[dustybumpers]

I'll put something together for you today.
I'm not sure why someone would put a 2g on a 3g truck, but...….

Keep an eye open later today when I go to the shop

I may make a new thread for Dukin to put up in the stickies

 

[Kaajot]

I'll put something together for you today.
I'm not sure why someone would put a 2g on a 3g truck, but...….

Keep an eye open later today when I go to the shop

I may make a new thread for Dukin to put up in the stickies

Cool!

I found a youtube video that showed a wiring splice change for a 2G to 3G conversion on the two black and white (or could be red, but pretty sure it was white) third line goes into the new 3G connection, but is that ALL that has to happen? I think there's more too it, per your earlier post, as a wiring splice and increasing the ground (negatives) to a larger gauge is far too easy.

And I know you said 1991, but I continue to find most information online states up to 1994 was 2G alternators out of the factory, which makes sense because it looks like Ford's quality control reworked all the known bugs on defective parts or problematic parts starting with 1995 Gen 9s.

Really will be keeping my eyes peeled for a 1995 or 1996 now in good condition -- would prefer a 250 or even 350 though if I'm buying another F-Series.

 

[Kaajot]

And another thing

Also, because I know amps and watts and volts, but didn't really size out my 750 Watt Amplifier, it turns out I may have been running my Amp at 100% without a buffer assuming I have a 75-80 amp alternator.

To run at 60% of the power drain on the 750 Watt Amp, I needed something more like 120 amp+ alternator, and I didn't even factor in the actual power drain from the truck's normal components.

So.... that could have been an electrical problem from the get go also, assuming I don't have a 3G 135 amp already installed.