Where is the ground located between engine and frame?

There's no single, universally located "ground" between an engine and frame. The grounding connection(s) will vary depending on the specific vehicle, engine, and design. However, they are typically found in one or more of these locations:

* Engine block to frame bolts: A common method is to use one or more of the engine-to-frame mounting bolts as grounding points. A wire might be attached to the bolt head or even use the bolt itself as a conductor.

* Dedicated ground strap or wire: Many vehicles use a dedicated heavy-gauge wire or strap specifically for this purpose, running directly between a clean, unpainted surface on the engine block (often a specific grounding lug) and a similar point on the frame.

* Within the engine compartment wiring harness: The main ground wire for the engine electrical system might incorporate the connection to the frame as part of its path.

In short, you need to examine the specific vehicle to find where the ground is located. Look for thick wires or straps connected between the engine and the frame, often near the engine mounts.