Electric choke

NOpe. You are measuring voltage from one end of the harness to the other.

Let's talk about this a DIFFERENT way. Let's say there is 1/2 volt lost (figure out of the air) in the harness.

So if you were to turn the key to "run" and measure the battery, let's say the battery -- at the posts -- measured 12.6V.

Let's say you now move the positive probe over to the ignition run buss on the firewall, and you measure 12.1, which corresponds to our "1/2 volt drop" we picked out of the sky for example.

In the above test, you keep the second meter lead grounded to the battery neg. post.

THIS 1/2 VOLT is being lost IN THAT HARNESS, in that circuit path I mentioned.

So you can measure that drop DIRECTLY by putting one probe on the battery pos. (the source) and the other probe out where the IGN system connects (the load) and you will then measure the 1/2 volt directly.

THIS ASSUMES that you have no drop in the ground circuit.

Voltage drop gets WORSE with more CURRENT

Let's say you had a trunk mount battery. If you extended your test leads, and you clipped one meter lead to battery positive, and brought the meter up and clipped the other lead to the starter stud, then went in and turned on some accessories, heater, lights, or cooling fans, electric pump, and the ignition.

You might measure a tiny drop with a nice big cable, or NOTHING because you aren't drawing all that much current, and you are using HUGE cable. (There will BE some drop, your meter might not be sensitive enough to measure it)

BUT if you were to disable the IGN so you can crank the car, you might measure a few tenths of a volt in this setup.

THE POINT is that WITH ENOUGH CURRENT even a huge battery cable can exhibit voltage drop.

You can check lots of things this way. Let's say you suspect a bad battery connector or bad cable. Disable the IGN so you can crank the engine and load the cable.

Put your meter probes -- one on battery post, other probe on battery clamp, and crank the engine. The meter will show you how much loss there is IN THE CONNECTION ITSELF

IF you suspect a bad cable, "stab" your probes on the battery CLAMP (not the post) and at the other end of the cable stab your probe into the END CONNECTOR on the cable, NOT the stud it fastens to

The meter reading, while cranking, will give you an idea of how good/ bad the cable is.

Some years ago, on my old Ranger, the ground battery cable went down to the frame, had an "inline" connector which bonded the cable to the frame, then continued on and jumpered over to the engine block.

I was having trouble starting, but the lights were nice and bright. The cable had corroded AFTER the ground tab on the frame, so the engine block was not seeing a good ground.

Only took about 10 minutes of head scratching and a meter to figure that ground HAD TO be bad.

Hope this helps