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Old 05-23-2019, 09:13 PM
oldskewel oldskewel is offline
Join Date: Nov 2014
Location: SF Bay Area
Posts: 1,061
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And to experimentally verify that the jump port is in the circuit, I just did a quick test using my clamp ammeter on my 3.0i.

I clamped around the cable immediately to the starboard of the jump port cover.

When starting the engine, indicated current through that cable increased positively and then quickly (within about half a second) overloaded since it exceeded the 100-Amp range of my meter.

Then, following the start, while the engine was idling, current showed negative (driven by the 120A Valeo alternator, flowing back toward the battery) of 80 Amps, dropping to 60 after a few seconds, continuing to drop, which was enough to remove any doubt I may have had.

Like I said a couple of posts earlier, wiring diagrams on the internet show the 4.4i and the 3.0d having different setups (same as eachother, different vs. the 3.0i), where the jump port is at the end of the line. So in those cases, current won't flow past it except when jump starting or charging at the port.

But in the 3.0i, it's definitely in the normal path of high current. It makes perfect sense that any looseness or surface corrosion at the jump port would cause the port to get hot, and of course that should be fixed for many reasons.

Regarding the wiring diagram posted earlier, I think that branch coming off the alternator is just not there on my car. And I think the jump port is correctly indicated but mis-numbered as I suggested in that post.
2001 X5 3.0i, 190k miles, AT, owned since 2014
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