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<blockquote data-quote="keep_hope_alive" data-source="post: 8654504" data-attributes="member: 576029">You have done a good job testing and taking measurements.  Thank you for your efforts to date.Remember that a voltage reading with a DMM is a relative measurement looking at the potential difference between the two points being measured.   If the ground isn&#039;t making good contact with metal, you will get odd readings and low readings.  open voltage at the back should match the voltage at the front.  With no load, there is no voltage drop.  If it doesn&#039;t match, the ground is usually suspect.Grounds will fail over time for two reasons:1. they loosen unless you&#039;ve bolted it with &amp;gt;1/4-20 and lock washers/lock nuts.2. they will always corrode over time.  If you sand away paint, you expose metal to oxidation and it will rust.  Even if it stays &quot;dry&quot; there is enough moisture in the air to cause oxidation. Even if wires are touching ground, they may not be making sufficient contact electrically.I recommend cleaning/sanding your ground point to expose bare metal again.  Clean/sand your ground terminal/lug.  When you bolt it (not just screwed) use locking washers or lock nuts and torque it down.  Lastly, silicone can help stave off oxidation (assuming it isn&#039;t already really humid when you make the connection). Additionally, make sure any ring terminals aren&#039;t loose around the wire.  you should be able to pull on your connections with reasonable force (5lbs or so) and they should remain tight.  Replace any ring terminals that are suspect.The same rules apply for battery connections.We usually remove amps and bench test when they are suspect.  We&#039;ll even direct wire them to the battery (with an inline fuse) to test function independent of the vehicle.  In your case I suspect connections.</blockquote>

[QUOTE="keep_hope_alive, post: 8654504, member: 576029"] You have done a good job testing and taking measurements. Thank you for your efforts to date. Remember that a voltage reading with a DMM is a relative measurement looking at the potential difference between the two points being measured. If the ground isn't making good contact with metal, you will get odd readings and low readings. open voltage at the back should match the voltage at the front. With no load, there is no voltage drop. If it doesn't match, the ground is usually suspect. Grounds will fail over time for two reasons: 1. they loosen unless you've bolted it with >1/4-20 and lock washers/lock nuts. 2. they will always corrode over time. If you sand away paint, you expose metal to oxidation and it will rust. Even if it stays "dry" there is enough moisture in the air to cause oxidation. Even if wires are touching ground, they may not be making sufficient contact electrically. I recommend cleaning/sanding your ground point to expose bare metal again. Clean/sand your ground terminal/lug. When you bolt it (not just screwed) use locking washers or lock nuts and torque it down. Lastly, silicone can help stave off oxidation (assuming it isn't already really humid when you make the connection). Additionally, make sure any ring terminals aren't loose around the wire. you should be able to pull on your connections with reasonable force (5lbs or so) and they should remain tight. Replace any ring terminals that are suspect. The same rules apply for battery connections. We usually remove amps and bench test when they are suspect. We'll even direct wire them to the battery (with an inline fuse) to test function independent of the vehicle. In your case I suspect connections. [/QUOTE]

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