So I picked up a new truck and started noticing this issue at night.

This issue affects all the lights on the truck. I am attempting to get a general idea of what I could be dealing with here and how to go about fixing it.

I upload a Vid to YouTube so you can see what is going on. If you turn your speakers up you can hear me rev up and the lights start to even out.

http://youtu.be/283YEVmdcl4

I didnt get the voltage gauge in the video but you can see it jump up and down. Less than half an inch nothing crazy just enough to be noticeable. I passed by my local auto store and had them check out the battery and alternator which both passed. I also checked the grounds and they both seem to be ok.

I would love to hear some opinions as i do not have the funds to just start swapping stuff out.

 

Voltage Regulator (part of alternator, usually replace alternator when this is bad) is either bad or the fuse for that circuit is bad. The fuse label in your manual should say something like "generator" or "Alternator System". Mine did the exact same thing, ended up being that the fuse was good it just wasn't properly seated in the slot. BTW this should be a fuse in your engine bay fuse box.

The alternator converts mechanical energy into a 3 phase AC signal. This voltage is then rectified (no negative voltage). But there is still a ripple in the voltage after these steps. The voltage regulator makes sure the voltage stays at a pretty flat level. It also keeps the voltage constant under RPM changes.

It would be really helpful if you would add a signature containing your year, engine, transmission, 2wd or 4wd to help out in further questions.

Judging by your video I would say your truck is late 90s early 2000s. My fuse for this circuit was fuse 14 (30 A) and should be light green.

 

Thanks for the info!

I compared my local shops (Advanced Auto Parts & Napa) and this is the cheaper one.
https://www.napaonline.com/Catalog/C...+50028+2028044

Say I purchase a new higher amp alternator would it not include the voltage regulator? I am thinking of doing just that and upgrading my ground cables.

 

Yeah do your "Big 3"

"Big Three" upgrade means improving the current capacity of three cables: 1) alternator positive to battery positive, 2) battery negative to chassis, and 3) engine ground to chassi

 

Heres the How-to and its even on a 3.0 to make your life easier. This one also includes an alternator upgrade.

https://www.ranger-forums.com/interior-exterior-electrical-123/how-get-most-your-electrical-system-104555/

 

Wow thank you! This is a great write up. It will really make my life easier. I owe you!

 

HAHAHA I don't know about that. This stuff is available to all. Just go through the How-To section. Lots of great mods on there.

 

There are so many mods to do. Once I am able to save enough the "Big 3" is my top priority.

I went by advanced auto parts on the way home from work and picked up from cleaning supplies as my paint in dire need of some help.

While I was there i brought up this topic with the employee.

https://www.ranger-forums.com/2-9l-3-0l-v6-tech-32/flex-fuel-spark-plugs-119781/

We could not find AGSW12FM so I had him bring out the finewire version they had in stock. The motorcraft part number he brought back was AGSF32FM.

Any experience with these plugs?

I plan to have new plugs, spark plug wires, 200amp alternator, upgraded positive and ground cables and new terminals when I fix my regulator issue. Hopefully these new plugs work out good.

 

SP-495 is an alternate part number

 

So the ones I got are not the correct ones? SP-432 is the part number on the ones I have.

 

not sure. thats the # from the thread you put up

 

Thank's for all the help Masteratarms93

I will be trying the ones I have. Hopefully they turn out good.

 

Well,

I grew tired of the pulsing at night so I went by the local auto part and picked up a new voltage regulator.

Began swapping it out early sunday only to realize that one of the alternator brushes was broken in two pieces just floating around in there it seems. Alternator was in rough shape so I figured I would just pick up a new unit.

I exchanged the voltage regulator I had purchased for the OEM spec alternator. Everything went on fine on the swap and she started just fine. After a few seconds the battery light comes on and the volt gauge sitting at about 1/4 of the way up.

I went back to the engine bay thinking maybe the belt tensioner was not right but everything looked nice and tight. I then noticed a cable that was running to the positive battery terminal with a fuse I had figured to be a part of the aftermarket alarm system disconnected. I connected the wire like it was before and viola no battery light and volt gauge rock steady.

After some review it looks like the cable is spliced and ends up on the middle plug on the alternator. Here are some pictures showing the path from the battery.

Any ideas why this was done? Can I properly replace this to factory specs?

 

Well, after a few days with the new alternator with new voltage regulator I am still having the "pulsing" issue with my lights.

Any ideas as to what could be causing this?

Sorry for all the questions guys but I am lost with this issue and its driving me crazy!!!!

 

I'm going to take a WAG at this.
Go out and measure the diameter of the crank pulley and post it here.
Methinks the previous owner installed an underdrive pulley , and the alternator is running right at the threshold it needs.

 

I went through the fan this morning before work so I couldn't get in there very well but I believe the crank pulley is 8 inches across. I will verify tomorrow as I will be doing some work on the truck.

 

If it's about 8 in across then it's not an underdrive pulley.
Take off the serpentine belt and make sure you have full travel on the tensioner. They will corrode inside and stick , not keeping the belt tight enough.
Take it off (only one bolt) and spray some PB blaster inside of it.
I'm leaning this way as the pulsing seems to coinside with the revolutions of the belt. One rev = one pulse.

 

If it were mine, I would start by finding an EVTM for the truck, or at least the charging diagrams from one. Most Ford dealerships will run you off copies of whatever pages you need.

Next, I would cut the black tape and zip ties off of that mess in your 3rd pic to see WTF is going on there. I would bet money that there are some wires in there that aren't wired correctly.

It would appear that they tried to replace some damaged wiring and probably messed it all up.

Let me know if you need the diagrams, I have access to AllData.

 

I'll give you a head start...

 

Thanks dbranger. I will be taking a look at the wiring. From the diagram you posted I cannot tell where the cables lead but I should have a better understanding once I see what's there.

Thanks again!

 

Hi Guys,

Can someone confirm that this is the correct evtm manual for my truck?

I does not specify model or engine type. My guess is that this is for all rangers but I would like to confirm before I buy the wrong one.

http://cgi.ebay.com/ebaymotors/1999-...#ht_2160wt_862

 

EVTM's cover all engines and options for a particular model. The "particular model" in your case is a 1999 Ranger. So, that's the correct EVTM.

 

I was able to get to determine what was going on under all that tape.

The yellow and white wire was cut and was connected straight to the battery with the fused wire.

I wired it back into the original connection and sure enough was getting the battery light on the cluster. Drove it like that for a bit and verified that it was not charging the battery which it is not.

Following the diagram my next clue would be to swap out the fuses but i want to verify which ones they are if they have a way to test.

The diagram shows me number 14 and 5 in the battery junction box in the LH side of the engine bay. The fuses seem to be the 60 amp box type fuse. Is there a way to test these?

 

Fuse 14 (Green 30A Mini) under the hood, in the battery junction box, sends voltage to the alternator when the key is on. So, with the battery charged and the key on, you should be able to read battery voltage on the YE/WH wire at the alternator. If not then the fuse could be bad. If the fuse is good, shows 0 ohms resistance accross the legs, then the YE/WH wire or the wiring inside the battery junction box could be bad. You should trace the entire YE/WH wire back to the juntion box and check for problems before you take the juntion box apart.

Also, the WH/BK wire is the "sense" wire. It tells the internal regulator that the alternator is charging and shuts the dash light off. This wire should show about 1/2 battery voltage with the engine running. If not, check the WH/BK wire out as well.

 

Thanks so much for everyones help with this. I was able to return the wiring back to the original spec and replaced the blown 30a Alt SYS fuse.

Lights keep steady with all accessories on so needless to say I am quite happy. Now let the real mods begin!