Gauge Sending Units

[jonny-rockets]

Where is the easiest place to tap into power and ground from the engine bay? The sending units I have to hookup obviously need power, and I feel its a bit redundant to run power/ground from the cabin back to the engine bay..

this is the trick i am using to route the cables into the cabin:

http://i148.photobucket.com/albums/s5/abacall/step18copy.jpg

Anthony

[Bu11dogg2]

Where is the easiest place to tap into power and ground from the engine bay? The sending units I have to hookup obviously need power, and I feel its a bit redundant to run power/ground from the cabin back to the engine bay..

I'm confused.... do you need to find a power source in the engine bay or inside the car?

[jonny-rockets]

i just need to power the sending units, they have positive and ground leads coming from them...

i have all the power sources inside the car all taken care of, and i considered routing some power/ground cables out to the engine bay to hookup the sending units, but then decided that may be redundant, and there is probably a 12v line and ground i can tap into within the engine bay.

[Bu11dogg2]

I'd have to look :(

[Robk0000]

SO, what you are really asking for is "where is the easiest hole to get throught the firewall"?

if so, there should be one about 6" above the one you pointed out, its alot bigger and there is almost nothing going through it. Atleast its there on my car...

[banned4life]

isnt there a giant battery in your engine bay for power? :rofl:

I cut a hole in a rubber stopper under the wheel well into the cabin

[jonny-rockets]

SO, what you are really asking for is "where is the easiest hole to get throught the firewall"?


nope, because when you run the wire through the clutch entrance you don't have to mess w/ the firewall. (see the pic above)

isnt there a giant battery in your engine bay for power? :rofl:

yes exactly - i was hoping for a local 12v lead coming off of that battery that I could tap into..

[Robk0000]

yeah, but the clutch entrance gasket is on the lower part of the car, or firewall. The upper one, goes directly to the battery making it easier, no?

[jonny-rockets]

the lower clutch entrance comes out just beneath the fuel filter.

http://i148.photobucket.com/albums/s5/abacall/step19copy.jpg

if i do that, i don't need to mess with poking a hole through the firewall, since it is riding next to the clutch cable, right?

[Robk0000]

i dunno, maybe your car is differnt. i meant by using an existing gasket in the firewall, just cut the gasket...

Do whatever is easier, im not really to sure where the clutch cable is on my car, lol.

[jonny-rockets]

yea if you want to do it that way, i'd just tap into the parking light like the original DIY suggests. That's the easiest and most sensible.

grassyknoll,

what regulates when the parking light is on/off?

[Robk0000]

there is two wires going to the parking light, one is + other is grnd. The only thing that regulates it is the parking light dial on your light switch. Or the red button on the steering column

[jonny-rockets]

there is two wires going to the parking light, one is + other is grnd. The only thing that regulates it is the parking light dial on your light switch. Or the red button on the steering column

crap.

i'd rather not have it hooked up to that switch.. i want to be able to have my sending units on, and my parking lights off.

any suggestions grassyknoll?

[jonny-rockets]

does anyone know how much DC power these gauge sending units actually draw?

i am thinking of just running a cat5 cable through the clutch gasket. 8 wires is more than i need, but 24awg cat5 can handle up to about 20 watts.

as a side note the gauge wires coming off the sending units look about 24 awg anyways..

[method]

Shouldn't you size it for voltage drop/amperage for the particular sensor?

[jonny-rockets]

i have 2 sending units total that need power. if they are in a parallel circuit pulling 12v each from my ACC line, wouldn't that be fine?

what exactly do you mean? i only have moderate experience with wiring, so by no means an expert!

[Robk0000]

you will not have any voltage drop in this dc circuit, trust me. The wiring in the harness can handle 15 amps before starting to heat up and require to derate due to heat loss. What exactly is a sending unit? If you are just saying 2 gauges they will draw under 500 mA, which is nothing. The Acc fuse is rated for 10 amps which is just turning on the radio, gauges in the car and now your other gauges.
The only problem i can for see is an overload on the wire causing your gauges to be dim, which wont happen.


*electrician btw*

[jonny-rockets]

the gauges are already powered...

the sending units are how electrical gauges work. instead of having a mechanical connection to the gauge (like a vacuum line for boost, or the oil line for oil pressure) the mechanical connection is made to a sending unit which transmits the signal back to the gauge as an electrical signal.

these units of course have 3 wires coming out:

1). power
2). ground
3). actual signal for the gauge

[jonny-rockets]

cool it sounds like the cat5 idea will work fine.

if each sending unit draws 500mW then im in the clear for sure.

[Robk0000]

Cat 5 in exposed areas like under the car and in the engine bay will be horrible, do not use it. You will redo the wiring in several months, the cat 5 copper is a solid piece not allowing much flex before breaking.

[method]

+1 for stranded. Not only will it not break from fatigue you can handle more amps on stranded.

[Bombay994]

Please do not use the Cat5e, there is a reason it isn't already used in cars. Take the time to route the proper wires, you won't regret it.

*also an electrician*

[jonny-rockets]

Cat 5 in exposed areas like under the car and in the engine bay will be horrible, do not use it. You will redo the wiring in several months, the cat 5 copper is a solid piece not allowing much flex before breaking.

you sure on this? i was planning on using plenum coated cat5, which is much more heat resistant.

and actually i did not get solid core wiring, i got stranded core. (not a solid piece).

[jonny-rockets]

solid core cat5 is used for long runs, stranded core is for patch cabling...

the cable i have is a patch cable.

[jonny-rockets]

Please do not use the Cat5e, there is a reason it isn't already used in cars. Take the time to route the proper wires, you won't regret it.

*also an electrician*


what would you suggest? the sending units have lead wires that look same same gauge (24).

[jonny-rockets]

here is some more ino on the type of wire i would use.

http://www.webcamproshop.com/ProductDetails.asp?ProductCode=AC-4304&click=3844

Extreme outdoor gel filled, UV rated, plenum, Cat 5 cable. Perfect for extreme weather conditions. Can be ran exposed or buried. Tested and verified to 350 mhz. Enhanced category 5E+. $.55/foot

[Robk0000]

Go to autozone and buy a trailer towing package, just the wiring harness, its usually about 25 ft of brwn, grn, blk & whte. Also its 14 or 16 gauge wiring, along with that stuff get some wire loom material, i have a few feet if you need it but, its for big wiring. Also i ahve a few feet of 500 kMill copper :) A bit over kill,

Bombay, what company do you work for? Im with Gemini Electric and currently up in Laconia Middle School or Concord Hospital depends who decides they want mad skillz for the day. lol

[jonny-rockets]

if i go the 14 or 16 gauge wire route i can get wire from my work for free. (power wire).

the cat5 would be free for me too.

so i was going zero cost..

i dunno hmm...

[Robk0000]

get the power wiring and some loom if you are going under the car or in the engine bay.

[method]

You can get away with 16g wire.

[Bombay994]

Go to autozone and buy a trailer towing package, just the wiring harness, its usually about 25 ft of brwn, grn, blk & whte. Also its 14 or 16 gauge wiring, along with that stuff get some wire loom material, i have a few feet if you need it but, its for big wiring. Also i ahve a few feet of 500 kMill copper :) A bit over kill,

Bombay, what company do you work for? Im with Gemini Electric and currently up in Laconia Middle School or Concord Hospital depends who decides they want mad skillz for the day. lol


Actually part time for the Air Force Reserve, mostly on planes which means all high amp DC power.

[jonny-rockets]

bam!

obvious solution is obvious.


only route power, plus the 2 signal cables out to engine bay.

ground wherever i feel like it in the engine bay.

use power cable from work. (well insulated, probably 16 or 14 gauge).

yes?

amidoinitrite?

[jonny-rockets]

what should I wrap these wires in to protect them from heat? I am not as concerned about the turbo sending unit, but since the oil pressure sending unit will be very close to the engine block, I should probably get some form of thermal tape to wrap the wires with..

[Robk0000]

wire loom? i it all over my engine bay, you can get it at radio shack. hoe depot or anywhere really.

[jonny-rockets]

any specific type of wire loom? i thought wire loom was just a generic term.

im probably wrong though

[jonny-rockets]

bump?

[Robk0000]

its like a plastic based weave that looks pretty, you can either get the hardend cloth type or the hard plastic tubing that looks ghey.

[jonny-rockets]

pics please?

[Robk0000]

homedepot ****
http://tbn0.google.com/images?q=tbn:4JMKOWg9hhAFhM:http://www.gcustoms.com/shared/Wire-Loom.jpg

wooven ****
http://www.cableorganizer.com/images/roundit-2000nx-fr/roundit-2000nx-fr-s.jpg
late reply sorry