[t vago]

I think I have found a good spot for the electric pump module ("good" meaning that it'll actually fit and be oriented correctly). However, there are a couple of caveats.

First, the stock power steering pump, reservoir, and PS fluid cooler will have to be removed as a unit. I will not be able to keep the stock unit in the engine bay and have the electric pump installed at the same time.

Second, the pump will very likely sit low in the engine bay, which will make checking the power steering fluid level somewhat of a challenge.

I think I can live with both of these caveats. I will make some mounting brackets to mount the electric pump module on the truck chassis, and then wire it up.

After some digging around, I could find the input and output pins on the pump module itself.

A1 - high amperage +12VDC
A2 - high amperage ground

B1 - idle up output to Toyota ECM (active high or active low?)
B2 - 4 pulse/rev speed sensor input
B3 - "TC" diagnostic connector
B4 - N/C
B5 - EHPS relay control (active low)
B6 - WOT cutout input from Toyota ECM (possibly active low)
B7 - "TS" diagnostic connector
B8 - N/C

C1 - switched ignition +12VDC
C2 - "SIL" diagnostic connector
C3 - N/C
C4 - warning lamp output (possibly active high)

So, it should be a simple matter to come up with a T flip-flop to interface my truck's VSS output (8 pulse/rev) to the input of the pump. I will probably rig up a small relay that switches a ground signal, controlled by the idle-up signal, that would be fed as the power steering pressure switch signal into my truck's engine computer. I'll probably end up using some sort of comparator circuit, taking its input from the throttle position sensor, which would provide the WOT cutout input for the pump module. Wiring up the warning light ought to be pretty simple, too.