1994 C1500 5.7 Frankentruck; No crank, no lights

[Casca1964]

Have a no crank no lights /power situation on my 1994 C1500 ext cab 2WD;
Replaced battery and got 12.4v at posts; tested at power junction block using batt neg got 1V. Tested at starter solenoid (with solid clean ground) and my digital multimeter spun thru numbers like a slot machine in Vegas... (Im electrically impaired so not sure what that means) also tested at another two post block on the firewall on the drivers side (there's a black wire that runs from the power block post where the positive battery wire attaches to this small two block post) and again the multimeter kept flashing various numbers.
I removed the pos battery cable (both need replacing anyway) and tested them while connected to the battery (and nothing else) both cable to the solenoid and the power junction block leads read 12.4.
1. anyone have thoughts on what makes a multimeter flash numbers instead of giving good reads? (again ground was either battery itself or a clean solid surface)
2. anyone know what that small junction block on the driver side firewall is called?? (two post box.. one post at 12 the other at 6.. about 1 1/2" x 1 1/2" square bolted to the firewall with two self tapper type screws at the 3 and 9) see attached.. in the foto the top wire connected at the top post runs back to the power block post that also includes the wire from the pos battery cable far right post in second foto

Ill be replacing the cables regardless as said.. just wanted to know if I should replace the two blocks mentioned above.. or maybe the starter .. as I said the reading at the post was flashing number.. with cable removed (testing JUST the cable) was 12.4v..
confused

 

[Schurkey]

Charge the battery, it's only about 80% charged. Open-circuit voltage (OCV) should be 12.6--12.8, somewhat depending on temperature.

You must be registered for see images

 

[Casca1964]

copy all.. its brand new battery OOB.. think I need a trickle charger boost.. or jump it?..

gotta change cables for sure tho.. see below

 

[Schurkey]

"New" does not mean "fully charged". A "jump" isn't the right approach. Trickle-charger overnight might be.

Yeah, you need new cables.

 

[Erik the Awful]

If you're not one of those weirdos who thinks side posts are great, this is your opportunity to go top post.

Note that the first 4" of those two thinner wires is actually 16 gauge fusible link. You absolutely need fusible link there.

 

[Casca1964]

"New" does not mean "fully charged". A "jump" isn't the right approach. Trickle-charger overnight might be.

Yeah, you need new cables.

Thank you Sir!!
getting it done.. cable inbound today

 

[Casca1964]

If you're not one of those weirdos who thinks side posts are great, this is your opportunity to go top post.

Note that the first 4" of those two thinner wires is actually 16 gauge fusible link. You absolutely need fusible link there.

Copy all.. another question the wire running from the batt j-box (post where 1x fusible link wire runs from pos batt cable) on the pax side to the small j box on drvr side.. is that also fusible link?

Also I bought a battery that has both top and side post... so I could be flexible if finding the exact cable wasnt possible.. but just finding the correct side post battery cables for this beast was a nightmare.. (as anticipated) let alone finding top post work arounds.. and if the answer is fashion my own.. brother "Mongos" skills aint that good.. just sayin.

 

[Erik the Awful]

Yes, that wire also has fusible link. I just replaced that wire on my son's truck last week. I ran the replacement wire across the fender instead of down to the motor and back up the firewall.

Why not DIY? Go to the junkyard and grab the battery cable from a BMW X3. The battery is in the trunk, so they're super long.

Get the Harbor Freight wire crimper.

Hydraulic Wire Crimping Tool

Amazing deals on this Hydraulic Wire Crimping Tool at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Get some terminal lugs to fit the wire (I keep a selection on my shelf).
1 gauge - www.amazon.com/gp/product/B09QKTBHX9/
2 gauge - www.amazon.com/gp/product/B0BDRV7SXV/
4 gauge - www.amazon.com/gp/product/B09QKTCBKS/

Red & black heat shrink tubing
www.amazon.com/gp/product/B07X33GKJY/

 

[Casca1964]

Yes, that wire also has fusible link. I just replaced that wire on my son's truck last week. I ran the replacement wire across the fender instead of down to the motor and back up the firewall.

Why not DIY? Go to the junkyard and grab the battery cable from a BMW X3. The battery is in the trunk, so they're super long.

Get the Harbor Freight wire crimper.

Hydraulic Wire Crimping Tool

Amazing deals on this Hydraulic Wire Crimping Tool at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Get some terminal lugs to fit the wire (I keep a selection on my shelf).
1 gauge - www.amazon.com/gp/product/B09QKTBHX9/
2 gauge - www.amazon.com/gp/product/B0BDRV7SXV/
4 gauge - www.amazon.com/gp/product/B09QKTCBKS/

Red & black heat shrink tubing
www.amazon.com/gp/product/B07X33GKJY/

I like your style Sir.. I figure first order of business its get her running.. after that Ill experiment!!

Now about that small wire.. I believe you're referring to the wire that runs from the positive side of the batt to the junction box on the passenger side of the fire wall (jpeg ending in 162839).. that one .. on the factory replacement .. does indeed start low by the solenoid and is configured to run up the firewall.. (that I may change ..cause in truth.. this is how I found it.. is it easy to add extra wire to reach that length? and if yes what gauge is required?)
Sorry, I was actual referring to the wire that runs from that junction block post.. along the top of the firewall to the small two post block (what is that damn thing called BTW?) ref jpeg ending in 162854

 

[89RCLB]

I like your style Sir.. I figure first order of business its get her running.. after that Ill experiment!!

Now about that small wire.. I believe you're referring to the wire that runs from the positive side of the batt to the junction box on the passenger side of the fire wall (jpeg ending in 162839).. that one .. on the factory replacement .. does indeed start low by the solenoid and is configured to run up the firewall.. (that I may change ..cause in truth.. this is how I found it.. is it easy to add extra wire to reach that length? and if yes what gauge is required?)
Sorry, I was actual referring to the wire that runs from that junction block post.. along the top of the firewall to the small two post block (what is that damn thing called BTW?) ref jpeg ending in 162854

what is that damn thing called BTW?

That is a circuit breaker. First guess is it was supplying power for a trailer or possibly a slide in camper. Follow the wire that leaves the breaker and you might be able to figure out what it's doing and if it's still needed.