Factory Wiring Experts, Help Me Understand My Lindsey Racing Reference Sensor Harness
08-28-2007, 09:41 PM
#1
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Factory Wiring Experts, Help Me Understand My Lindsey Racing Reference Sensor Harness
I am in the process of rebuilding my spare engine harness for my 951, and am installing all the replacement harness kits that Lindsey Racing currently sells. This post is just to enlighten me on why I am wiring the reference sensor harness the way it says to.
As the LR instructions say for retaining the use of the factory O2 sensor:
"Remove the original DME pin #5 from DME plug. This terminal is shared with the O2 sensor ground and a brown wire (chassis ground). Cut the brown wire just off the pin seperating it from the O2 ground wire. Solder or connect the end of this brown wire to the bare wire ground pair on the replacement harness. Install the bare wire grounds with re-attached brown wire back into pin #5."
This is where my question comes in. If you are removing the chassis ground wire from the O2 ground wire, and placing the brown on the new reference sensor harness and plugging it in to pin #5, aren't you killing the ground for the O2 sensor since you are disregarding that wire now that you cut off the brown?? Or is the reference sensors tied into the O2 sensor somehow?
As the LR instructions say for retaining the use of the factory O2 sensor:
"Remove the original DME pin #5 from DME plug. This terminal is shared with the O2 sensor ground and a brown wire (chassis ground). Cut the brown wire just off the pin seperating it from the O2 ground wire. Solder or connect the end of this brown wire to the bare wire ground pair on the replacement harness. Install the bare wire grounds with re-attached brown wire back into pin #5."
This is where my question comes in. If you are removing the chassis ground wire from the O2 ground wire, and placing the brown on the new reference sensor harness and plugging it in to pin #5, aren't you killing the ground for the O2 sensor since you are disregarding that wire now that you cut off the brown?? Or is the reference sensors tied into the O2 sensor somehow?
08-30-2007, 01:03 PM
#2
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I don't have the LR harness. But from looking at the '86 wiring diagrams, it looks like the LR instructions are slightly wrong. Pin #5 on the DME connector is attached to a common ground wire (brown) and the shield for the *reference* sensor, not the 02 sensor. So by attaching the new harness to the brown wire and leaving the other wire unattached, you are merely abandoning the old reference sensor harness in favor of the new one (which is of course what you're trying to do).
Why the instructions talk about the O2 sensor I don't know. Maybe its a cut-and-paste error from another set of instructions. But it looks like if you do what they say, it will work.
Why the instructions talk about the O2 sensor I don't know. Maybe its a cut-and-paste error from another set of instructions. But it looks like if you do what they say, it will work.
08-30-2007, 03:55 PM
#3
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After I got into the harness on my desk and had my wiring diagrams in front of me I realized also that LR's instructions were wrong in the sense that pin 5 is not shared with the O2 sensor, and like you said is actually the chassis ground and one of the reference sensors. The O2 sensor wire is actually shared with the other reference sensor on pin 23, which is the pin LR says to put their harness into if your not using the factory O2 sensor. I talked with Dave on the phone for a good 10 minutes or so after I realized this to make him aware of this slight error in the instructions and he said once he found his skeleton 951 harness he would check it out and change the instructions. He said I was the first person to ever comment on it.
