Humvee cluster acting up solved

[Eli77]

"I have a good electronics background and have done lots of wiring and troubleshooting "

YES, you do. Good analytical thinking and pulled the prints. BIG POINTS to Springer... Beyond the call of duty.

I note too... the volt meter swing to low "yellow" guessing about 19 +/- volts, figuring in the slow ballistics of the needle movement to get a "snapshot". Not a solid "DEAD" short... but a unwanted very low resistance or there is a wire getting very hot, very fast. LOL.

As noted, Pull one of the CB-2 leads should get one going in the right direction. Then follow those wire numbers out to all the BLUE connection, one at a time. Clear the "blue" circuits one at a time (print is the truth table) and see where it lead one. Keep in mind the breaker could be wonkie too.

PAY attention to everything he as stated.

The applied theory is spot on... Process of guess elimination... as nothing is text book with HMMWV. LOL

As a double check... does the truck start and run with CB-2 disconnected?

That's my guess for the year, CAMO

Hi to answer your question. Yes the truck start and run with the cb-2 disconnected but the brake light and the wait light won’t turn on at all ( I guess due to the fact that the cb2 disconnected). But it start and run

 

[Retiredwarhorses]

Quick question. Could a bad glow box control cause a short? Just out of curiosity?

Clicking on and off is normal for what appears to be bad PCB, yes…the bad PCB a can kill the gauges, yes, the bad PCB can trip the circuit breaker, the CB is a dynamic breaker, meaning…as long as the shirt is present, the CB aid tripped.
take a picture of your start box under the dash.

 

[Milcommoguy]

Hi to answer your question. Yes the truck start and run with the cb-2 disconnected but the brake light and the wait light won’t turn on at all ( I guess due to the fact that the cb2 disconnected). But it start and run

Thanks for the test. If I got this right... Were chasing RUN CB-2 popping? Follow along with Springer's 'Blue Lined Print' Don't worry about the Wait or Brake LED's. Check out the wiper motor and washer. Easy, could just unplug it at the motor / switch to eliminate that. Note the wires feeding it up thru the windshield and contacts are in play too. (not likely IMO but keep it in mind)

Follow all the blue branch circuits going every which way (gauges) Remove one at a time and test... to success. If handy with a mulitmeter low Ohms scale will work too. Any add on, non standard hobby hack wiring? Suspect anything out of place.

The factory "road map" shows all logical points that the electron should be going to power the necessary circuits. Some have found a "short cut" to return or ground (failed device or frayed wire) My guess it's not a dead short, but very low resistance to draw sufficient current to POP the breaker CB-2.

This is going to be a good exercise in troubleshooting... all said and done.

Eye on the prize, CAMO

 

[Milcommoguy]

Clicking on and off is normal for what appears to be bad PCB, yes…the bad PCB a can kill the gauges, yes, the bad PCB can trip the circuit breaker, the CB is a dynamic breaker, meaning…as long as the shirt is present, the CB aid tripped.
take a picture of your start box under the dash.

Question from the peanut gallery. Point me to where the CB-2 RUN circuit feeds power to the PCB and or how it controls gauges?

Lost with the road map in hand, CAMO

 

[Action]

Question from the peanut gallery. Point me to where the CB-2 RUN circuit feeds power to the PCB and or how it controls gauges?

Lost with the road map in hand, CAMO

CB2 get power from PCB pin B via wire 29c/b. Then 29d feeds power to the cluster and other things.

 

[Eli77]

Wow !!! Who would have imagined. !!!! The stupid wipers motor. Man. Well thank you all for you help. I really appreciate it. Solved

 

[Milcommoguy]

CB2 get power from PCB pin B via wire 29c/b. Then 29d feeds power to the cluster and other things.

Your not quite right IMO and research. My point is we are trouble shooting down stream of the PCB. Main battery does flow thru it.

Battery IN on engine harness "E" and right out cabin harness "G"

Battery out cabin harness "G" is NOT under any control / treatment by said "SMART" PCB, NO fuse, NO protection, NO nothing. It is a direct connection.

(unless some wackberry was looking to melt some wires, start a fire, watch smoke billow out of PCB. Note: Cabin harness "B" from "RUN" switch is the control signal and power to "wake up" the sleeping box & start glow control)

The only circuit protection are the two circuits breakers CB-1 and CB-2 (basic truck M998 3 speed) Lighting circuits are built in the lighting switch.

CB-1 to the heater motor and CB-2 to the gauges, horn and LED's that draw ZIP in relation to wiper motor & washer and the CB-2 breaker rating.

Not being on site...MY guess was pointing to a froze up wiper motor and switch was ON or jacked up too. Problem now solved,

Process of elimination... Just like I did for the over engineered $$$ PCB and shared the build here, CAMO

"Cabin" or "Body" Same oh same oh connector.

 

[Chichimarz]

No, sorry. Please see attached picture and explain to me at what point in that circuit would the light come on? Hint, the answer is never. If any of the positive (BLUE wires in the diagram I posted) were shorted to ground anywhere it would be the same as the circuit in the picture below. Electricity will ALWAYS take the path of least resistance. Doesn't matter the voltage, doesn't matter if it is AC or DC.

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