wth would make a 5v circuit run 9v? This is seriously frustrating!

[H@xtGSX]

I have the p0340 code and can't for the life of me get rid of the damn thing. I have swapped in 3 different CAS's and another ECU. The voltages read right elsewhere, but at pin 88 (cam position sensor signal wire) I am getting 9v on a 5v circuit and a can't figure out why! Its driving me insane. My next option is to start re-wiring the car, and after having done the timing 6 times now, it seriously seems like the easiest route at this point.

Does anyone know why it might be doing this?

 

[sniver]

Unhook the cas and ecu and measure the resistance of the wire in question. Then with both unhooked measure resistance from the pin 88 wire to both a 12v like, and ground.

pin 88 to cas should be under 1 ohm ideally
the pin 88 wire to 12v or ground should be out of limit.

I'd be leaning toward a partial short to a 12v line.

 

[Infamous33]

Did you have the CAS unplugged when checking voltage at pin 88?
The voltage is supplied by the ecu, throught a resistor. If there is higher voltage at the ecu you could have another resistance source in the wiring to the cas. There is nothing else on that wire and no inline connectors.
I would run a new wire from the ECU to the CAS. If there is high resistance in the wire it could be a serious project to find the problem in all the harnesses. By overlaying the wire you can rule out resistance in the circuit as your cause.
The way it works is this:
With only one load in the circuit, when that circuit is grounded, all of the voltage should be used up. If there is a second 'load source' (ie- corroded wiring) the voltage and amperage will not be fully used up by the first load (in this case, the internal resistor at the ECU). The CAS is simply a grounding device, therefore it supplies no load on the circuit unless there is an internal problem with it.
Just testing the resistance of the wire will not give you a positive answer. With twisted wire, there are multiple strands of wire and having only a single strand with give you a good resistance result, however when you apply voltage to that wire you could have current flow issues... ect,ect,ect.
I will stop here as this is turning into electrical class....
Make sure you use the same size wire and heat shrink the connections to prevent water intrusion.