Stuck on Alternator issue

[stationjj]

I have a alternator charging issue. It started with me not getting a solid 14.7 on front battery with engine running, and no Gen 1 light. I had good reading a light from Gen 2

After reading various post from Barrman, Warthog, and others I have done much work, but I still have alternator issues. I feel I understand a great deal about how the alternator charging system works. I also feel I may be confused on something or missing information?

List of what I have done.

Cleaned electrical connections including the 12 volt block by GP resistor.
Cleaned the battery and 24 volt block.
Cleaned connections and replaced all bulbs on the dash.
Cleaned and rebuilt Gen 1 with rebuild kit from CUCV electric
New exciter wire plugs
Replaced the large fusible links on 12 volt block, Gen 1, and GP resistor.
Replaced the heater switch
Had both batteries tested by AutoZone, and my load tester They are good and can handle a load.

Today after doing all of this I get Gen 1 light, but now Gen 2 light isn't coming on.

Testing on what I have done so far.

Engine off Key off Battery 1 12.37, Battery 2 12.56.
Engine on Key on Battery 1 11.88, Battery 2 12.44.

My reading from the exciter wire I am not sure about, and confused. For example with Key off testing the red wire on Gen 1 12.37, Red wire on Gen 2 24.93. At the same time I get a reading on the brown wire as well, but will slowly drop. I thought that on the brown wire I should have no reading ZERO.

I plan to rerun the exciter wire testing again on Sunday. The batteries charge is low and drained, so am I am doing a slow recharge of both batteries tonight and will run a load test on the them after they are fully charged. I will report back after I rerun the test Sunday.

At the moment I am confused and not sure what I need to do next. I am considering Pulling Gen 2 and having it rebuilt. I got rebuild kit. start tracing wiring?

Anyone have any advice or suggestions?

Thank You,

stationjj

 

[SouthernSteel]

Looks like Gen 2 needs to be rebuilt.Because if im not mistakin 14.4volts at each batteryis what your suppose to have. Thus giving you a combined reading of about 28volts while running.Your correct about zero on the brown wire.:] Good luck i had alot of problems with my m1008 in the beginning i feel for ya.Hang in there you will figure it out.Do you have the TMs for the wiring diagram printed off they are at the top of the cucv forum page.

 

[Keith_J]

The small red wire on the 2-pole plastic connector is the sense, not excite. On both, the excite is brown. There must be 24 volts to the #2 (right side) alternator, 12 volts to #1 (left) when the ignition is on.

Why the need for the sense wire? The fat wire delivering the current has variable voltage drop, the sense wire assures the battery will get the proper voltage regardless of the current the alternator is delivering.

 

[stationjj]

It concerned me when I am getting voltage on the brown wire. The initial and first reading is I have voltage on the Brown wire, then it starts to drop slowly. So to completely understand I should have NONE ZERO voltage on brown wire with key and engine off even though it does drop?

I guess I need to start studying the wiring diagrams. They are confusing, but I discovered a tutorial in the TMs.

Any idea why I am getting voltage on brown when I shouldn't or where to start?

Thanks everyone for your help. Trying to wrap my head around it all.

stationjj

 

[stationjj]

Keith J

Thanks for your input! I want to verify my readings from the 2 pole connector. I will do this on Sunday.

The batteries are weak and will do a load test on them. I want to verify the batteries are good.

I just checked the Front battery after it finished charging I get a solid 12.98. That's better than the 12.37 I got with Key off.

Thank You,

stationjj

 

[stationjj]

I got the battery's fully charged.
Key off Engine off Battery 1 12.89 battery 2 12.69
Key on Engine On Battery 1 13.35 Battery 2 12.63

Key off Engine off Gen1 red 12.88, brown 0, Gen2 red 25.58 Brown starts off 5.2 and drops to 0

Now with the Engine on is where it gets odd.
Key On Engine on
Gen1 red 12.42 brown 12.52
Gen2 red 25.83 brown 0

Why am I getting voltage on red wire with engine on? It should be 0 right?
With Engine on I am getting only 13.35 battery 1. Keep in mind Gen1 was just rebuilt.

I am confused and not sure what my next step should be. Rebuild Gen 2?

Any advice or suggestions?

Thank You,

stationjj

 

[Keith_J]

I got the battery's fully charged.
Key off Engine off Battery 1 12.89 battery 2 12.69
Key on Engine On Battery 1 13.35 Battery 2 12.63

Key off Engine off Gen1 red 12.88, brown 0, Gen2 red 25.58 Brown starts off 5.2 and drops to 0

Now with the Engine on is where it gets odd.
Key On Engine on
Gen1 red 12.42 brown 12.52
Gen2 red 25.83 brown 0

Why am I getting voltage on red wire with engine on? It should be 0 right?
With Engine on I am getting only 13.35 battery 1. Keep in mind Gen1 was just rebuilt.

I am confused and not sure what my next step should be. Rebuild Gen 2?

Any advice or suggestions?

Thank You,

stationjj

The small red wires should be hot at all times, this is why they have fusible links. This tells the regulator in the alternator the charge state of the battery, regardless of current induced voltage depression on the 8 gauge wire connecting the output to the battery terminals.

On alternator 2, having no voltage on the brown wire when running means the regulator is not being turned on. Double check from the indicator bulb in the dash to the alternator, you might have a break in that circuit. When running, make a jumper from the small red to the brown wire, if the output increases, the alternator is fine, the problem is in the external wiring.

 

[stationjj]

Keith J,

Thank you so much for your assistance here! You have given me some direction here.

You have gotten me thinking, I took out the whole dash and tried to clean the thin printed circuits. Maybe in my cleaning attempt I was too aggressive? In the end I fixed some issues, but created others? A learning experience.

I would like to clarify a few things to make sure I understand.

I shouldn't worry about the voltage on the RED wire with engine on? Correct?

Create jumper wire and jump the red and brown wire. Then check voltage at battery. If the voltage output increases the alternator is fine, and I should should suspect problem in wiring?

With the Gen 2 light out an not coming on, it's not completing a circuit which can cause a decrease in voltage output on Battery?

Thank You for your help!

stationjj