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What is this sensor

WebDog

WebDog

NAXJA Forum User
Location
Center City, MN
So i have been trying to figure out where these red wires go and i looked under the car and there is a sensor in the engine that has the oem wiring cut and this spliced into it... I would much rather have it wired the way its suppose to. i have no idea why they would have spliced it into the windsheild fluid low sender?

Any idea what this sensor is and why someone spliced it?
Could i re-attach the oem wiring or could that cause problems?

I have high lighted the sensor and the oem wiring that was cut.


http://farm3.static.flickr.com/2043/...5ffabdbd27.jpg
http://farm3.static.flickr.com/2358/...44077e44f6.jpg
http://farm3.static.flickr.com/2030/...7f6b60241c.jpg
http://farm3.static.flickr.com/2148/...a31bbe6c94.jpg
 
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From what I can make out of the pictures, it looks like something rigged up to bypass the O2 sensor. You circled the sensor in the exhaust so that's what I'm basing the guess on.

How or what the circuitry does, I have no idea. If you changed it back, you may well have error codes thrown.

Again, this is merely speculation from what I'm seeing in the photos.
 
its a 88

the O2 sensor is still wired stock and is in the same harness, i know the O2 is fine since i had to replace it to pass smog.

The sensor im talking about goes into the engine block just above the oil pan.
 
so any idea why someone would rewire it like this?

If i reconnected the oem wiring how could i tell if it was fucntioning correctly?

I just dont like random splices under my hood.
 
The first and fourth pictures are splices into the electric fan relay. Is there a switch inside the cab that turns of the electric fan manually? Its probably spliced into the windsheild washer circuit to get the 12v power to operate the relay. By the By, it looks like your low windshield washer light probably doesn't work.

The sensor that you circled is the knock sensor. Why it is disconnected, I don't know. Its part of the emission system, and would affect your MPG.
 
the knock sensor controls timing and (if working properly) should sense any pinging or spark knock and adjusts the timing accordingly so it doesn't cause any damage.

My knock sensor was busted at the harness, I jammed the thing back together and the jeep runs fine, although I do run 89 octane gas. Some people have run without a knock sensor for years, as long as you aren't hearing pinging or spark knock you're probably okay. It's one of those parts that I keep meaning to replace, but can't justify the $105 dollar price tag, and havn't gotten around to pulling one from the wrecker yet.
 
Well i just passed emmisions, but on the highway i do notice a little knocking some times.

I think i will connect it back up to the way its suppost to be wired, maybe i will trace the wire and make sure its not melted first.

So if its working properly i could possibly get better milage? and if its not working would i get a CEL?
 
CEL not applicable. No codes on RENIX (87-90)

at first I thought it was CTS so when washer light came on ment you were out of warm up mode and in, I always mix this up open loop mode as opposed to closed during warm up
 
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Harlee&Tahoe said:
CEL not applicable. No codes on RENIX (87-90)

at first I thought it was CTS so when washer light came on ment you were out of warm up mode and in, I always mix this up open loop mode as opposed to closed during warm up
Click to expand...
That's actually a pretty neat idea, any idea how you'd modify it to do that? I'm no electrical whiz..
 
Ok so the last few days its been hot out and i notice that the elect fan is not coming on, so i look and the wires that where cut are the ones that go to the sensor in the radiator. I was having to turn the AC on since that forces the fan on to not overheat, it was getting close to 240.

Do you think its possible the PO thought that the knock sensor was the temp sensor and thats why they wired it like this?

I think i will reconnect it back the way it should now that i have the other missing peice of the puzzle.
 
Sounds like the PO was a wiring wiz........................and now you are the proud owner of a giant rubberband ball

esidfklg.jpg
 
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