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Old 10-01-2007, 07:07 PM   #13
RBV Technical Advisor
Join Date: Aug 2007
Location: California central coast
Posts: 4,638
Vehicle Year: 1991
Vehicle Make: Ford
Vehicle Model: Explorer
Rep Power: 33
MAKG will become famous soon enough

Not everything, but you're going to have to explain how the computer monitors the 5v reference signal as it leaves the ecm and heads to the tps. There is nothing between there except for the supply wire itself. The computer has no way to know if it "got there" or not. There are precious few redundant systems in an automobile. Running a whole bunch of wires to monitor one might be called for in the Space Shuttle (where that wire failing might kill someone) but it just isn't in a light truck.

If it didn't "make it there," the signal wire is grounded. A resistor with no current is the same as a wire. That's Ohm's Law.

Ungrounded circuits can sometimes behave the way you describe (not one so simple as this one, though). But not unpowered circuits.

1990 VW Jetta GL, 1.8L 8V gasoline engine, manual transmission, painted in oxidized red paint and ponderosa pine sap, unknown mileage.

1991 Exploder, 4.0L, M5OD-R1 manual transmission, electronic BW1354 transfer case, 3.54 gears, 31 inch tires, icky two-tone blue paint with little clear coat, 230K miles.

1972 Chevy C-10, 250 I-6, SM465 (2WD) four-on-the-floor, 3.73 gears in a GM 12-bolt, puke green with a white cab. The "4 wheeled trash can," with x70K miles. x is probably 2.
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