1st See my Cave,
Gen 2 HL MotorYou said "not real strong in the electrical department." is a problem...
Plugging them in/out of working 87-88 Fiero works but not a good plan either. Module in it now might fail after playing w/ plugs for no reason.
Bench test needs Gen2 HL wiring and 2 HL lift assembles so can run the module and motors up and down.
Do Not flip motors up/down. Go up, wait, go down, wait, etc. Other wise could fry a good module.
But that's only give you bare minimum works or not...
Add very small "12v"
Light Bulbs in parallel to both motors.
Likely can backprobe each motor plug w/ unfolded wires of 194 bulb or other using less power.
Lights. Not LED. Must work w/ "reverse polarizing" and most LED won't work w/o extra parts.
Light should go off same time as motor hit End of Travel. IF NOT and light stay on ~ 5 sec then module has problems and Test Fails.
Even then, Used modules can have iffy even crack solder joints etc in them and test now may pass but after shipping, installing, and whatever and be "DOA" or soon cause you headaches.
Example: I won't bother even testing until can check/fix iffy joints to main plugs etc. inside of an used module.
If you have no equipment and little or no clue what to look for that's a problem. If can't solder well, find something else to fool w/ before you try to fix actual parts because Too small or too big irons, too hot/cold irons, etc, can make bad joints, lift copper off the board and fry parts.
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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave