Parasitic draw- starter motor

[gcbennet]

My ‘85 M998 w/6.2 has been experiencing a parasitic draw. Inconvenient but not terribly detrimental yet. The troubleshooting to narrow down the culprit is as follows:
-disconnect neg battery terminal of aft battery.
-Set multimeter to the 10A setting, making sure the leads are in the appropriate positions.
-place one lead on the neg battery terminal and the other on the disconnected neg cable eyelet.
-reading should be zero or thereabouts. If it’s not, you have a parasitic drain.
-one at a time, disconnect things and take a reading. The alternator and starter are the typical culprits apparently.
In my case the starter was the culprit. Troubleshooting further I disconnected cables and wires one at a time to narrow it down. Turns out when I disconnect cable 81A (pictured) the drain stops. Unfortunately I traced this cable all the way forward to the main cannon plug going to the S3 box so there’s not much I can do at this point.

 

[Milcommoguy]

" S3 box so there’s not much I can do at this point. "

Yes there is. It also come out of the box on the body connecter. Disconnect batteries, remove body connector. Reconnect amp meter in line like before above and see what you read? S3 box does have a few microamp keep alive draw.... BUT not 2.13 Amps unless it smart BRAINS are fried. Other circuits are feed AND hot all the time off the body connector. Not done just yet.

Reason to disconnect batteries ?? If one gets sideways with any connector coming off or going back on box... sparks are possible. That will be another BIG problem.

What goes in, goes out, CAMO

 

[gcbennet]

" S3 box so there’s not much I can do at this point. "

Yes there is. It also come out of the box on the body connecter. Disconnect batteries, remove body connector. Reconnect amp meter in line like before above and see what you read? S3 box does have a few microamp keep alive draw.... BUT not 2.13 Amps unless it smart BRAINS are fried. Other circuits are feed AND hot all the time off the body connector. Not done just yet.

Reason to disconnect batteries ?? If one gets sideways with any connector coming off or going back on box... sparks are possible. That will be another BIG problem.

What goes in, goes out, CAMO

“It also come out of the box on the body connecter. Disconnect batteries, remove body connector.”

Not sure exactly what you’re referring to. The cable in question goes directly from the starter to the S3 box cannon plug, which tells me there’s something amiss inside the box but not something to disrupt normal operation.