I have a 1986 Defender, ex-military. These have a so-called "inspection socket" (that's the name on the wiring diagram), which I believe are meant for jump starting. They have heavy gauge wires, and I believe I have seen NATO jump start cables with this specific connector style.

Now the wiring behind it is a bit odd, as it's routed via the starter solenoid, which kinda acts like a power distribution point, so I want to verify that this is:

  • 1) Good and safe practice.
  • 2) Find out the reasoning behind it, ie. why not connect to the battery bank?

I have pretty much rewired the whole truck already to bring it up to more modern standards, except for a few things like these.

This is the wiring diagram: enter image description here

  • 3: Inspection socket
  • 34: Alternator
  • 36: Starter
  • 37: Starter solenoid
  • 41: Battery bank (it's a 24V vehicle) with main power switch

1 Answer 1


If it is intended for jump-starting, then that wiring takes the power directly to where it's needed - the starter. I presume that the wires between 3, 37, 34 & 41 are all thick, heavy-duty ones? If so, I'd say it ought to be ok, as long as the connection on the starter solenoid is good enough for the current.

  • But the starter still won't go unless the key or equivalent is used, to energize WR and pull in those contacts. A socket you can plug into is more reliable than trying to get a good connection with most jumper cable's thin clamps.
    – WGroleau
    Jun 30, 2017 at 3:34
  • Yeah, that's the whole point - electrically, the circuit shown above is exactly the same as if the socket went to the battery +ve (well, except for the cut-off switch), but taking it directly to the solenoid reduces the amount of wire and number of connections between the socket and the starter - also, depending on the layout of the engine bay, might be a lot more convenient to get to (I can't remember which side of the engine the starter is on a Defender, but on a series it's about as far from the battery as you can get...)
    – Nick C
    Jun 30, 2017 at 10:11
  • Yeah, all thick wires. -- WR is energized by turning the ignition key to "START". -- The starter is on the left hand side, as are the batteries (which are under the driver seat, in the LHD version). The "inspection socket" is actually on the right hand side of the car, could be NATO spec or something that requires that, would probably make more sense to put it closer to the starter. Anyway, thanks for the feedback, much appreciated. I will check the wiring for quality (old car), perhaps change the socket for a more common one, but will leave the wiring as is.
    – svenema
    Jul 2, 2017 at 8:57

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .