M 998 Electrical COVID??

[92'M998]

Hi All -

I have been talking about the battery saga in other posts. This is what happened now.

1. Batteries were load tested and checked with a multimeter at 12.7 V
2. Put them back into the compartment. Hooked cables and nothing happens when the key is turned.
3. No Power to anything.
4. What should I do next to see if I can get her started.

I appreciate all assistance. Thanks. J

 

[papakb]

Take your multimeter (voltmeter) and see if you have any power on pins V & W of the STE/ICE connector. This will verify that the vehicle is seeing the batteries and you should have power to the truck.

On the engine connector to the control box make sure you have power to pin E. This is the input to the control box and the first place the power goes.

It comes out of the control box on pin G and from there goes directly to the B terminal on the RUN - START switch.

 

[Ajax MD]

The PCB protects against improperly connected batteries. Are you certain that you cabled them up correctly?

 

[Bulldogger]

I don't recall in your other thread if you verified all connections for primary power, so perhaps check the battery wires on the underside of the body, opposite the ones you can see in the battery compartment?
Agree with tracing the +24V line to the start switch and PCB, regardless.
BDGR

 

[86humv]

If you have a Key switch...they go bad all the time....put a stock start switch in.

 

[Milcommoguy]

86humv and the guys are right on that. Going to be a heck of a story when rig is back up and running.

New Covid resolution from the "bear with a radio"

I pass on trying to figure out electrical problems here. While simple on the surface (for me and many) not having the bigger picture of history, what been added or removed, last known condition, just gota see it... basically who screwed with it last (NOT saying anyone is bad here) Is just a can of worms of guessing and bandwidth. Not saying it hasn't been fun trying.

As we all know or should, likely one little connection of the whole of the system (unless it's burnt to the ground) it just becomes a guessing game with little crumbs of info here and there.

If one is lost in the woods, have a map. With electricity get the schematic or print and follow it through.

The learning, knowledge and a logical approach will be everlasting. Likely to stick in ones brain for the next time something craps out. Once done a time or two, one can walk right out of the HumV forest of wires. If out on the trail, be home by dinner too.

Guessing is like lost and going in circles. Wiggle and Jiggle brother are helpful but not true boy scouts. Having the mulitmeter is like GPS, if one know how use it. With little practice, never lost again. (confused sometimes, but going in the right direction)

Be that Eagle Scout and get the MAP BADGE, CAMO

A little ka-wink-e-dink... just had the prints blown up 3 X 6 in feet, so I am really lost. LOL

 

[papakb]

Years ago I took the basic M998 electrical schematic out of the -20-3 manual down to a Kinkos copy shop and had it double sized and then lamminated. That way I could use a grease pencil on it when I was troubleshooting. It's been invaluable over the years. The trouble with this theory is you have to understand electrical circuitry and theory because unlike misreading a roadmap where you can backtrack your error, miswiring makes things not work in some cases and burn up in others.

 

[Retiredwarhorses]

Hi All -

I have been talking about the battery saga in other posts. This is what happened now.

1. Batteries were load tested and checked with a multimeter at 12.7 V
2. Put them back into the compartment. Hooked cables and nothing happens when the key is turned.
3. No Power to anything.
4. What should I do next to see if I can get her started.

I appreciate all assistance. Thanks. J

start switch for one, but do you get any voltage at the starter? You have a pos and negative at the starter.
a bad EESS start box can cause same issue, there are also 2 breakers behind the instrument cluster.

 

[Milcommoguy]

Years ago I took the basic M998 electrical schematic out of the -20-3 manual down to a Kinkos copy shop and had it double sized and then lamminated. That way I could use a grease pencil on it when I was troubleshooting. It's been invaluable over the years. The trouble with this theory is you have to understand electrical circuitry and theory because unlike misreading a roadmap where you can backtrack your error, miswiring makes things not work in some cases and burn up in others.

Nothing is easy...But can be if one applies oneself. First timer with a map or schematic... anyone would be lost.

How long did it take to learn North - South - East and West. Many more symbols on any road map than any Humv print.

Learn the few electrical symbols (beginners ok to use a legend) and after a few minutes of applied focus things become clear. What the parts are and do comes next. Soon one should be going forward and backwards... rather in circles. Note schematics have straight line. When I have explained it to others at the work bench...after a few minutes you get the "AHA LIGHT" comes on.

I taught my boy (he did all the brain work) and earned his amateur radio technician license at age seven, KM6BVZ. Thought I'd throw that in there for too old to learn crowd.

It's OK to not be familiar with a problem. That why it's a problem. Understanding the basics is not magic or a theory. Take the time, expand the mind. Will save a ton of time and guessing.

Hopefully HumV was already wired up once correctly. For most part just verifying go-no go as one stays on the trail. (playing here... circuit)

Want to build your own trail ?? Now that's a hike for the point man to break.

Papakb out in front, CAMO