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Old 02-10-2013, 09:10 AM   #1
DonaldE
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Question Ambient Temp Pigtail

So I've been up and down my driverside harness and looked at all the wiring diagrams I could find, and I've still not managed to find where the pigtail derives from on my 330. I found what I thought was a mistake in that I had a plug that is shaped exactly the same as the one required plugged into what I THOUGHT was an extra horn that someone had added when replacing my driver's side headlight assembly. Turns out there is in fact two horns in the front bumper from factory. So now that pigtail is unplugged until I can get it back into place.

An interesting thing about all of this is that my temp constantly reads -40, inspiring the thought that the two wires are out somewhere and obviously not making full circuit. But when I go through a car wash, the temp acts up and starts randomly displaying numbers and beeping from temps being below freezing, etc. This leads me to believe that wherever the wires are they are exposed close enough together that the water is making a small current between them and causing it to read differently. It varies how it acts up. Sometimes it climbs slowly 1 degree until reaching 120 and sometimes it just randomly spits out numbers.

At any rate, my question is this: How far back can the wires originate? I know the wires split off right where the fog light tail splits, but the only thing I could find coming from that point was the pigtail plugged into the horn. Could this be a mistake on some tech's part, in putting the temp sensor plug into the horn? Are the two connectors that simlar that they could be plugged in to either? Or is it more likely that I have bare wires someplace along the harness that are just too damn hard to fine without stripping all the cover off the wires.
Please advise

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Old 02-10-2013, 10:30 AM   #2
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Damn, I thought more people might know something about this.
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Old 02-10-2013, 11:30 AM   #3
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I'll look...brb

So they're 99% coming out of the e-box through that grommet in front of them, traveling along the hood and splitting along the way a few times, of course. Look to the side of your outer headlamp, to the side of the car...

You don't have a temp sensor or yours is just broken. You've found it's location and it's blank, is that right? It's down in the sealed compartment on the left front corner...a 'half cone' shape protruding up.

If you don't have a connector or sensor, some moron cut it off. Usually it's just a broken sensor and very common. Look up in the corner of the car under the hood with a good flashlight...remove skidplate and look from beneath if you can't otherwise find what you need.

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Old 02-10-2013, 12:00 PM   #4
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Well I removed the headlight assembly to see the entirety of the harness after diving behind the headlight. What I've found is the plug to the horn and fog. But no other plugs or exposed wires. I wonder if the plug into the horn ie in fact the temp sensor plug

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Old 02-10-2013, 12:04 PM   #5
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Honestly, I live in Texas and would be content with funding the wires and connecting them in order to compete the circuit. It's about 120 half the year anyway. And my rear defrost no longer works from PO leaving it on since the car turns it on automatically when started

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Old 02-10-2013, 12:18 PM   #6
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Honestly, I live in Texas and would be content with funding the wires and connecting them in order to compete the circuit. It's about 120 half the year anyway. And my rear defrost no longer works from PO leaving it on since the car turns it on automatically when started

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Someone will correct me if I'm wrong, but the ambient air temp sensor contributes to the car running well. I don't know what systems use it, but I believe it's more than just hvac...it's engine management also.

If you find that cone shape I'm talking about, it will be some wire that can reach it, or you'll find the pigtail tucked up somewhere...maybe with the connector. Do you have an aftermarket bumper? Maybe it was lost then?

I can't imagine that someone would have cut it back behind a splitting in the harness.

Oh, also, check realoem for harnesses...that might give you a clue. I'll look for that too for you...

Not much help I'm afraid:

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Old 02-10-2013, 12:21 PM   #7
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You might get some help from this thread, there are pictures of the wires shown on the first page:

http://forum.e46fanatics.com/showthr...erature+sensor

Page 5 has more pictures.... really a pretty indepth thread on the temps sensor.
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Old 02-10-2013, 12:25 PM   #8
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Someone will correct me if I'm wrong, but the ambient air temp sensor contributes to the car running well. I don't know what systems use it, but I believe it's more than just hvac...it's engine management also.

If you find that cone shape I'm talking about, it will be some wire that can reach it, or you'll find the pigtail tucked up somewhere...maybe with the connector. Do you have an aftermarket bumper? Maybe it was lost then?

I can't imagine that someone would have cut it back behind a splitting in the harness.

Oh, also, check realoem for harnesses...that might give you a clue. I'll look for that too for you...
Been on realOEM and there is a split off the harness that seems to be the correct plug, but it was plugged into a horn. Which I thought was incorrect, but I read on another post that there is two horns in the bumper. That compartment has been ripped off by PO. Curb I assume. What I haven't done is unplugged the other horn and hit the steering wheel to see if it still honks. That could confirm my suspicion. I can't imagine two separate horns, coming from two separate harnesses, running in two systems. But I wouldn't out it past BMW

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Old 02-10-2013, 12:26 PM   #9
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Originally Posted by shanneba View Post
You might get some help from this thread, there are pictures of the wires shown on the first page:

http://forum.e46fanatics.com/showthr...erature+sensor

Page 5 has more pictures.... really a pretty indepth thread on the temps sensor.
That was the thread that I read there is two horns

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Old 02-10-2013, 12:27 PM   #10
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Buy that working diag doesn't apply to my sedan

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Old 02-10-2013, 12:35 PM   #11
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Buy that working diag doesn't apply to my sedan

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I always just link to my model, saved on realoem...it's a lot quicker. Realoem.com save your model and have fun.

If there is fresh tape on some of the harnesses, maybe they hid the cut off wire under a split, as I said, but I can't imagine someone doing that. There are two horns...I thought they were on different sides of the car, but haven't really looked for them. BTW, it sounds like you might have to rig up an optional mounting area for the sensor, but that should be relatively easy.

Anyway, all I can say is that it's undoubtedly around somewhere, and undoubtedly in the front corner. Pull out the turnsignal if yours is separate like mine...know you said you had lights out too.

Good luck straightening this out. What you seek can't be too far away I don't think.
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Old 02-10-2013, 12:35 PM   #12
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But that wiring diag doesn't apply to my sedan

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Old 02-10-2013, 04:36 PM   #13
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I always just link to my model, saved on realoem...it's a lot quicker. Realoem.com save your model and have fun.

If there is fresh tape on some of the harnesses, maybe they hid the cut off wire under a split, as I said, but I can't imagine someone doing that. There are two horns...I thought they were on different sides of the car, but haven't really looked for them. BTW, it sounds like you might have to rig up an optional mounting area for the sensor, but that should be relatively easy.

Anyway, all I can say is that it's undoubtedly around somewhere, and undoubtedly in the front corner. Pull out the turnsignal if yours is separate like mine...know you said you had lights out too.

Good luck straightening this out. What you seek can't be too far away I don't think.
I appreciate you taking time out to help me. I would be shocked if the EMS gave two shits about what temperature it is outside
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Old 02-10-2013, 04:53 PM   #14
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I appreciate you taking time out to help me. I would be shocked if the EMS gave two shits about what temperature it is outside
I'm pretty sure it cares a bit; I'm almost positive it's part of the signal component telling the therm to open or close. But, I've been wrong before.
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Old 02-10-2013, 05:04 PM   #15
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DME has imputs from oil temp, engine temp, and radiator outlet temp. I think these would control the thermostat as well. When you think about it, the only time outside air temp would affect the engine is when the engine is cold. (Remember the old "choke"?) However, all these other temperatures will be at outside air temp (or near it) when you start the car in the morning.
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Old 02-10-2013, 05:16 PM   #16
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I'm going to have to correct myself. Just found, on page ELE-330 of the Bentley, a wiring diagram that shows the intake air temperature sensor wired to the DME. Not sure of the purpose yet, but I'm sure they didn't pick up this temp and not use it.
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Old 02-10-2013, 05:17 PM   #17
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DME has imputs from oil temp, engine temp, and radiator outlet temp. I think these would control the thermostat as well. When you think about it, the only time outside air temp would affect the engine is when the engine is cold. (Remember the old "choke"?) However, all these other temperatures will be at outside air temp (or near it) when you start the car in the morning.
This is my thinking. Especially considering that the engine will be way warmer than any outside temperature within about 2 minutes of starting.
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Old 03-13-2013, 06:30 PM   #18
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So I've found my temperature sensor wires and crossed them hoping to see 122 on the dash, but alas!
No such luck. Thoughts?
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Old 03-14-2013, 09:14 AM   #19
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Old 03-14-2013, 11:52 AM   #20
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My temp sensor has been missing since I bought the car and its been showing -40 for ever. My milage is great (around 32 mpg @ 80 mph) and accel is fine as well although not head snapping. Doesn't idle rough, ever and that includes +30 C in the summer and -25 C in the winter. Never has a problem starting, even if its been sitting for a week. My point is, if it affects how the car runs, maybe everybody should disconnect it.
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