Ok, since my meter is dead, I went into the garage and turned off the lights. Started the truck and turned on my headlights. Applied the brakes with the truck in park and you can actually see a little flicker in the headlights and hear the fuel pump change pitch. I listened to the alternator area and it sounds like either the idler pulley or the alternator has a slight grinding sound. Stuck a long screwdriver to my ear and the alternator case and I think it is it. Wish it was a little bit more noisy so I could pin point it, but I think it is it. Idler pulley is not that old. This is going to be one of those if I take the alternator somewhere to be checked it will show fine. But here we go off to see the wizard at the stealership...Unless you all have a different opinion.

 

You are on the right track. USE DENSO generators. I am still using the OEM Denso with 250K miles and counting. I finally replaced my Denso starter even though it mechanically, still worked fine but, it was just starting to short out on the solenoid and had a lot of wear.

Like I said before, the quality of the innards is what counts. Reman / after-market parts may look the same on the outside but, that's where it ends. They all use the same shells / castings / cases so they appear the same and will physically mount up without issue but, it's the quality of the innards that bites you down the road later on. Pay now or, pay more later is my philosophy.

So, back to the case in discussion: sounds like a failing generator to me and, that grinding sound is most likely a worn shaft bearing somewhere in the path. Since all spinning components are tied together via the serpentine belt, it will be difficult to root down the source of the grinding noise. I just went through this with a water pump on my Dodge. Super high pitch squealing noise that sounded just like a spent bearing and, I got out the prybar and a long vac hose and ear muffs and couldn't pin point it. It's one of those areas that is hard to identify where the root of the problem lies because, there's more rotating items there that all could be potential problems. You've got the generator shaft, the idler, the tensioner, the power steering pump, AC pump and, the water pump.

The noise migrates throughout due to being connected to both the block and through the belt. In my case, the pump was not the root cause of that super high pitch squealing. I was sure it was a spent water pump bearing or generator bearing. Believe it or not, a new, Gates belt was the root cause for the metallic sound / squealing.


CM

 

It's not accurate at all, but what does the gauge on the dash read when the truck is idling with everything off, and then turn things on, like HL's, AC and such?

 

The gauge on the dash does not really move to much however it is below 14 volts at idle and regular load on it. Does not really move to much when accessarys are brought into the mix. I spoke to the dealer who looked up my truck via the vin and my truck came with a 136 amp alternator. They want 206.00 for it where Napa wants 205.00 for a 120 amp so it is a no brainer. And no, I would have went with the dealer anyway. I've learned my lesson. Replacing the power steering high pressure hose and can't get the thing to budge at the back of the pump. Sprayed it down with pentrating oil and will try again in the morning. Thank god this is not my daily driver or I would be up poo creek. Thanks again.

 

Allright, took the alternator in and they can only test it up to 120 amps because of their computer system and part number system. They do not even stock a 136 amp alternator at the store. So it shows fine at 120 amps. So does 16 amps make that much difference? Now what to do? Do I try replaceing the negative battery cable with an oem one? Or do I bite the bullet and get a new alternator? I know that the alternator is the power and you would think that it is pointing in that direction. I will defintely get around this thing, grounds, and check again before Monday when the dealer can order the alternator in. Any more input is appreciated because two heads are better than one.

 

If your alternator tests fine at 120 amps, that should be more than adequate to the task..... Would hate to see you spend 200 bucks, and not fix the problem.

I would take a serious look at all cables, connections, and grounds before I went and spent 200 bucks.....

 

Going to check the ground jumper from the frame to the bed and if I have to I am going to run a new ground from the back to the front at the main ground jumper to the frame where the battery ground is. Stupid grounds..I'll show E'm.

 

16 Amps is a lot of difference by the way. Most alternators and generators are always fine up to almost their peak voltage. When approaching the upper limit, this is where they will start failing during test unless, it's a gross failure to where, it fails under a very light load on it.

I would get your meter up and running and TEST for voltage drop across the battery. You will find it with a meter vs. changing wires out and, you will find it very fast. It will take you less than two minutes to test this-seriously. TEST IT.

If your going to keep on the path you are on now, (replacing wires at random, the negative battery lead is the main area of voltage drop on a ground and, no need to go OEM on that as, you can go to any supply store that sells decent Cu leads- just be sure to obtain a thick-walled termination clamp vs. the Chinese POT-metal clamps that break in half when tightened down.

To simply rule out a short in the braking system and, or, the rear of the truck, simply remove the FUSE for the brake lighting CKT and retest. Then, I would pull the fuse for the power brake booster CKT (if you've got a separate fuse for it)

Remember, jumping grounds around to which, grounds do not short- the hot feed does. If ground were removed or, severed 50% of the strands, it still would not induce a voltage drop in the headlamp CKT or FUEL PUMP CKT respectively. Voltage drop is usually due to shorting a HOT to ground or, the supply is unable to meet the demand.

When you step on the brake pedal, there's a switch under there that is depressed that makes contact that completes the CKT to illuminate the brake lamps. If the ground were removed- it would simply not illuminate the brake lamps. It would NOT draw down. However, if the HOT were partially shorted, this would send partial voltage to ground thus, drawing down.

Now, on charging the battery, the NEG (-) BAT terminal is the most problematic for dimming lights, and other power related anomalies but, it usually affects everything and, at random. Tell tell signs are usually visual indicators at the top of the battery post such as discoloration and oxidation, carbon build up etc.

On my truck, if I depress the brake pedal hard, the engine speed does slow a bit, then comes up. HOWEVER, this does not affect the output voltage of my generator to induce a voltage drop.

I still think that either the generator is failing, the voltage regulator is failing or, there's a short in the braking system to which, it's either in the illumination CKT and / or, the power brake booster CKT.

CM

 

So I got the power steering hose replaced, and took the main fuse cover under the hood off and wouldn't you know it, the fuse for the alternator is 120 amps and the backside of the cover says 120 amp alternator. What the .....? I have found where the main connection for the rear of the truck is up under the drivers side by the wheel well and this truck has been through some high water before, up over the hood and did not die, thank god, so I am going to check that connection for corrosion and when I get the thing back together check voltage drop at the battery first and then diconnect the brake circuit and see what happens. Thanks again for all the input.

 

That is just info about the fuse, NOT the alternator/generator.