recent adventures in '84 vanagon electrical bonding from first time listee:

1. as per list suggestions, i measured dc voltage between body and engine
at high idle with accessories on and, sure enough, had a reading of
roughly 250 mV. it turned out that indeed the port side bonding strap
between body and engine was a high resistance. the solutuion, however, had
nothing to do with cleaning contacts or snugging down bolts. instead,
there was an 8 ohm contact resistance where the "engine side" connector
was crimped onto the copper braid. obviously, the bonding strap was
useless in this condition, and carried very little current; the crimp on
the body side was good. new, slighly longer connectors, crimped and
soldered onto the original bonding strap (for good measure, along with the
many individual grounding wires from ecu, etc), solved the problem.

as a side note, the much heavier bonding wire underneath van between frame
and transaxle case was in excellent condition.

2. the temperature guage on this van was unusual in that it read low, and
had a very small range - way down there on the left end of the scale.
serendipidously, i discovered a roughly 800 ohm resistance between the
upper thermostat housing, where the temperature sender is grounded via its
threads, and the rest of the engine. evidently, there is corrosion or goop
or something keeping the mounting bolts from making good electrical
contact. now, this 800 ohm is itself considerably greater than the
resistance of the sending unit at operating temperature, and could easily
explain the behavior of the guage. i simply provided a shunt using a test
lead with alegator clips, and now have reasonable readings on the guage,
with the needle below the led at operating temperature.

note: this van resides in mcminnville, oregon, and will be for sale in the
near future.