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Discussion Starter #1
Here's what's on my mind at the moment:

1) Is it allright to just tap my O2 gauge into the O2 and signal ground lines on the LM harness? I'm aware that everyone says to run the wires right to the sensor and to the battery ground, but then there's the controversy about "false rich" due to ground-path resistance.

I'm just wondering about how much inductive or capacitive load the gauge puts on its input. If you just tapped into those lines right before the LM, you'd be seeing exactly what the LM is seeing-accurate or not. Plus, the wiring in the car would be cleaner.


2)I'd like to unscrew my Oil Pressure Sending Switch(the one that operates the idiot light) and put the sending unit for my Autometer gauge there. Then I'd clip the wire at the LM end, and split it off to my gauge for a reading, and to a comparitor to emulate the idiot light functionality. The output of the circuit would go where the sending switch output went on the LM. What's the signal output of the sensor for the idiot light?

Thanks!!
 

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1) Which A/F Guage? The Autometer only draws about 40mA max, from what I see. The signal ground should be able to handle that load just fine. The Cyberdyne draws well over 300mA all the time because of the design of the internal voltage regulator (zener-shunt). In that case I would not hook it up to the signal ground as it will be hard on the isolation resistor in the ECU. Do you have a 4-wire oxygen sensor? If not, then I like to ground at the fuel rail bolt since it is the closest, electrically, to the sensor.

2) The idiot light is much more idiotic than that. It's just a dry contact that goes directly to the bulb in the instrument cluster. When the oil pressure drops below 4psi, the switch shorts the wire to ground. The ECU is not involved, at least on the cars I have seen ('91 and earlier). Some cars have and engine kill feature associated with that switch, but I'm not sure if Chrysler ever did it and if so, when.
 

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Discussion Starter #3
1)Actually, I'm talking about the ONLY REAL TURBODODGE A/F GAUGE, the Dawes one! :cool: Also--why'd Cyberdyne use such a crude voltage regulator-makes me want to not buy their stuff.

2)That's awesome. I will remove that connection and subvert the lead for my own evil purposes!
 
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