Hi again everyone,

So my 85 Cherokee only has an idiot light, (which didn't even work when I blew my head gasket and cracked my cylinder head), and I am trying to install a new temp sender and water temp gauge.

I have no idea what I'm doing, and could use all the help I can get.
Does anyone have any basic electric wiring advice or a good website for help? I do not know how to wire anything really, and I don't want to start a car fire with mistakes.

The instructions that came with the gauge said to connect the gauge to the ignition for power, connect a wire to the sending unit, and connect a wire to ground and if lighting is desired. Do I just get basic wires at the shop and solder them together? Is there a different way to do it?
Also should I connect wires to the ignition? Seems sketchy and I don't wanna mess up my ignition..
Sorry I am just completely clueless on this, and I've researched online and everything I've found just assumes that people know the basics of wiring, which I do not..




straightforward instructions, but over my head.. help!?





what are these 2 things on the left for? and all these nuts? do you use them with the lock washers to attach wires to the gauge?<br/>(I am assuming the top 2 nuts are for studs on gauge if you are mounting directly into the instrument panel)

 

Also the new sender has the same threads as the old sender, but it isn't screwing in all the way. Through research it sounds like this is okay since it is a pipe thread and tapered, so it doesn't need to thread all the way. Hoping this will work and it won't leak (no consensus on whether to use teflon tape, high temp sealant, or nothing at all)



new on left, old on right

 

Basically in idiot terms how do I do this:
"4. Connect wire from ignition switch to ignition (I) terminal on back of gauge."

 

What it means by connecting to ignition switch is that you want it to connect to where, when you turn the key, the Guage will cut on with everything else. Best way to do this is to look under your dash at the fuse box panel. Find an empty slot, with a test light, make sure it has power going to it when the ignition key is n the on position. Put a spade terminal on your wire and plug the wire into that empty slot. If you do that correctly. You should have power to your Guage when your key is in on position.

 

when you say it doesn't screw in all the way, do u mean it gets tight or that the new unit is bottoming out before getting tight because it's too long. If it's just getting tight then that's normal, it won't screw in all the way but just untill it gets tight.

 

1. Don't solder anything. Use crimp connectors like this and maybe this and possibly this (although, those are hard to get right. These are much better. Color indicates size, so make sure you get the right size. These are for illustrating type only.) You get the idea. I prefer nylon insulators (they are the translucent ones) rather than the cheaper vinyl ones.

2. Use a decent crimping tool, or better yet a really good crimping tool. (Watch the video . There are lots of good videos on Youtube from DelCity.) Do not use one of these common pieces of junk.

3. Do not get one of these kits. They are in every auto parts, hardware store, and discount place. They are very convenient, and total junk.

4. Learn to crimp correctly. Take a look down the tube of a butt connector. See the seam? That seam needs to be at right angles to the crimper. You want the jaws of the crimper flat against the seam so that when you crimp, the seam is pushed into the other side of the connector. If the seam is away from the jaws, it will be squeezed open. Not good.

5. Get a decent test light and a multimeter. Each has its place.

 

93XJeeper
So the sender is just getting tight, it seems to be working though because coolant isn't leaking out of it (yet). I used a torque wrench and got it quite a bit tighter than hand tight (couldn't find exact torque specs in my manual). I do not think it bottomed out.

As for the ignition switch, thanks that makes a lot more sense. Now what exactly do you mean by a test light? And I don't quite know how fuses and fuse boxes work, does the Amp reading of the fuse spot specifically matter?
Which spot on here would you recommend I use for the wire for power (labeled ignition on the gauge)?




I saw in a youtube video that I could hook up the (4th) wire for the light on the gauge to the fuse that is for the dimming the instrument panel/headlights. I found that (#7) on the fuse box. Could I do a "fuse tap" onto that fuse? (As seen here: )


Is anything I am saying making sense? I still am pretty clueless about all this, sorry.

 

So far for wires from the gauge:
(S) from sender, through firewall, to gauge
(I) crimped on a eyelet terminal to 18 gauge wire, attached with nut to the gauge, other end is free. planning to attach a spade terminal to free end and attach to a fuse spot somehow? as 93XJeeper Said
(G) crimped on an eyelet terminal to 18 gauge wire, attached with nut to the gauge, other end is free for now... was planning to go through firewall and ground it to the frame. can I ground this where something else is already being grounded? or no?
(L) light: there was already a small wire attached here, so I stripped off the end of another piece of 18 gauge wire, twisted them together and soldered, then used a heat shrink cover. the other end of the wire is free but I think I will be doing some "fuse tap" onto the 7.5A fuse on my fuse box that is on the diagram for dimming on instrument panel/headlights.

should I also put a ground straight off of the sender, onto a ground on the frame?

thanks!

 

for G, just ground it on the metal bracing underneath The dash, no need to go back through the fire wall, I typical ground mine on the screw on the far left side of the dash underneath by the hood latch.

For I, like I said, find an empty slot with 12v going to it and plug it in there. You can use a test light (basically a light that you plug one end to a ground and touch the prong to where you think you have 12v, if there is 12v, it will light up.) Or you could use a multimeter if you don't have a test light.

And then you can do the L like you said and tap into dimming dash lights fuse. Just make sure that is the correct fuse before doing so by checking with check light or multimeter.

Also, just remember, none of the fuse slots underneath with have power until you have your key in the on position.

 

Hey thanks for the help! I have it all wired up and ready to go, I am going to run it later to test if the gauge is working, and will update this.

But if anyone comes upon this post at a later time/wants to know what I did, here is a summary:

Gauge had 3 wires + an optional light with a wire off of that
Ignition wire: from gauge, 18Ga wire on eyelet terminal, an inline fuse (I think 5 or 10A), to spade terminal, into a hot open fuse spot on fuse box
I found this by connecting a voltmeter: ground black to black ground on battery, red to the exposed end of a wire, which had a spade terminal on the end of it. Plugged in the spade terminal to various open spots on fusebox, checking to see if it was 0 when ignition was off, and 12V when ignition was on. Was pretty quick and easy and now I have power to the gauge when ignition is on, but not when ignition is off.
Ground wire: struggled to find a good screw on inside lower part of dash, so went through firewall and to a bolt on frame, 18Ga wire on eyelet terminal from gauge to a larger eyelet terminal on bolt
Light wire: from light, crimped butt connector to a longer 18Ga wire, to a "Add a Fuse" where I put in a 10A fuse to Fuse Slot A, then put back the original 7.5A fuse to the Fuse Slot B, then put into spot where there used to just be a 7.5A fuse for instrument panel lights/headlights dimming. Doesn't seem to be dimming, but isn't a huge issue there is still light.
Sensor wire: from gauge, 18Ga wire on eyelet terminal, through firewall, to sender in the cylinder head with eyelet terminal on that end too.

Thanks for the help! Lots of research videos tutorials and other forums, help from you both on this forum, and a double check from a family friend to make sure I wasn't going to start a car fire, and it is all good to go! Now just will have to see if it operates correctly, and gauge actually moves in relation to temperature haha hope so!

 

It's working!! I let the car run for a while in the driveway (kinda a rough idle with AC on, had to give it gas at intervals, but thats another thing), and as the temp rose, the gauge gradually rose!
I mean I can't tell if it is accurate or not, but hopefully I won't blow another head gasket now! Wooooo thanks for the help I am super excited that now I know 20% more about electric work

 

great, glad you got it figured out!

 

Very nice!


Here's a good site for electrical info: http://www.the12volt.com/