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Oil Pressure Gauge wiring SOLVED!!


 _chiefjt

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I was gonna post this in Oly's 720 resto page but I didn't want his thread to be 2 pages of this. SO, I made it's own thread. I guess you could say it's a How-To but I'll just post this here since it's 720 specific.

 

I FIGURED THIS SHIT OUT!! Charlie probably knows this already and it's what he's talking about but I'll say what I did to try and help out some more.

 

Keep in mind the donor truck is an '84 720 and the truck it's going in (mine) is an '86 720

 

This is how you wire in the oil pressure sensor wire into an '83/'84 into a truck that doesn't have it.

 

The '83/'84 engine bay harness has a round white plug that is by the battery. From the T connector (and some other wires that go to the starter/alt/etc blah blah which don't matter cause all you need is the T connector and the 2 wires coming out of it). Anyways, STARTING from the T connector there's 2 wires. If you follow it back to where it goes, it goes into a white round plug, which on the other end of that plug goes into the main harness. Even if the truck didn't have these gauges the main engine bay harness will still have the oil sensor wire there on the main harness side of the plug. If one is to put these gauges in there '83/'84, to simply make it work for the truck. You take the old light sensor wire (yellow/green) out of the hole on the sub harness plug and put in the 2 wires from the T connector. One wire is yellow/green which will go into the hole you pulled just pulled the old one out of. The other wire is yellow/blue which is for the oil sensor and you plug that into the empty hole that's covered up. Everything is there you just need to wire it into the round white plug. Obviously color match the wires so they connect to the right wires on the other side. Then just install your oil sensor, plug the T connector in and bam, you will have a working oil pressure gauge. NOTHING INSIDE THE CAB WILL NEED TO BE TAMPERED WITH!  :thumbup:  Everything else is plug'n'play.

 

Now that will play a huge roll with wiring it into an '85'86. So FIRST off, sadly the the '85/'86 doesn't have this round white plug, BUT it does still have the wire that goes into the main harness from a plug in the engine bay. How do I know, Cause I checked continuity from the yellow/blue wire from the cab to a plug in the engine bay. It's the EXACT same concept as the '83/'84 except the plug is different. Instead, it's a gray squarish plug. And it still has the yellow/blue wire on the main harness to the plug. On the other end of the plug (sub harness) is an empty slot for the oil sensor wire to go so just plug that in. Again same concept, You CAN take out the oil light wire (yellow/green) or you can leave it in there. I suggest you leave it so you don't have to tear up the harness to remove it. All you gotta do is remove the oil light wire from the old sensor and plug it into the T connector. You will need the pin that goes into the T connector. So instead of plugging it into the sub harness plug, your plugging it into T connector removing the wire that's in it (if there was one in it) That way you can just plug it into the new sensor that allows the T connector. Also, to plug the oil pressure wire into the sub harness plug you need the pin that goes into it. It'll be skinny and you can get it from a hardbody.

 

All in all you do need to wire it in but only to the either white round plug for '83/'84 or to the gray squarish plug for '85/'86. I don't know how it is for '81/'82, I'm hoping its the same as the '83/'84

 

A LOT TO READ AND TAKE IN  :frantics:  so if you have any questions just post them up. I'll be glad to help.  :D

 

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I swapped a 4x4 harness into my 620... everything, and run a Z24 with trans case. It has an '85 4x4 dash to match and I added the oil pressure and volt gauges. I put the two wire oil pressure/gauge sender in the block but run a separate wire to the gauge. Taped up under the dash was the gauge wire harness but I didn't think about the engine harness end. Assumed it wasn't there or couldn't be bothered. Nice work! 

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I wish I could post pics but that requires a camera that I don't have. That's why I don't really update my thread anymore.

 

I will try and post pics of what I'm talking about as far as the plugs and stuff and also my install. I can't install it because I don't have a center console and the truck I got it from was wrecked so bad the passenger seat was touching the drivers seat. lol

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I read the part for my truck several times, and I am still just a little confused. I think I will print it out, along with Charlie’s, and go out to the truck to sort this out. I bet that works. Main thing is, Guam sounds so solid in what to do, I totally believe it!

 

Mike, I want to see that 620 someday- that sounds like an incredible mashup! Our 620 lived in central Washington and the dash just exploded to shit in about 4 years. It was such a specialized piece, too. But grafting in a 720 dash? What a cool idea! Just one of many cool ideas I read there. You certainly have taken the Lego truck concept to an extreme. I really wanna see this truck in person.

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I'll post up a picture of the dash. It's an '85 4x4 with the clock and tach option. The only thing left that is totally from the original '78 are the tail lights and the short harness between them.

 

'74 cab

Wooden flat bed.

'82 long box frame,

720 complete wire harness wirh 15 fuse box

Z24 and 5 speed

T-100 4x4 transfer case

Toyota SAS

F-150 leaf sprngs all round

'80s 720 rear axle

S110 200sx rad

Chevy Van modified drive shaft

Plymouth K car alternator 90 amp

D-21 powre steering box

720 steering column with variable pulse wiper

S110 electric windows

Dodge Daytona seats

720 carpet

GM side mirrors

MonteCarlo rear view mirror with map lights

Modified 16 (US gal) 720 long bed gas tank 

all i can remember for now

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For those who clicked this thread for pics. lol

 

'86 720 gray squarish plug

 

DSC01316_zps17e5817a.jpg

 

Plug coming from main harness. The wire that I'm pointing to goes to the plug under the dash. This is the wire I tested continuity from.

 

DSC01315_zpsa9303fdd.jpg

 

 

Other side of the main harness plug.

 

DSC01317_zps3670803c.jpg

 

What I'm pointing at is where the wire comes out through the other side

 

DSC01320_zps0319b727.jpg

 

Sub harness side of the plug. As you can see, there is something missing.That is where you will plug in the yellow/blue wire from the T connector. You will need this style pin so you can put the wire in there.

 

DSC01321_zps29f43768.jpg

 

Back side of the plug. Just put it in the empty slot

 

DSC01322_zps49d5942a.jpg

 

This is the wire and T connector plug that I pulled from an '84. So cut and plug in yellow/blue wire and connect yellow/green wire to existing yellow/green wire.

 

DSC01323_zps09c21893.jpg

 

 

 

I don't have any pics of the round white plug for the '83/'84 cause I'll need to go to the jy for that but it's the same concept. The only thing different would be the kind of pin that goes in the white plug. Anything else?

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For those who clicked this thread for pics. lol

 

'86 720 gray squarish plug

 

DSC01316_zps17e5817a.jpg

 

Plug coming from main harness. The wire that I'm pointing to goes to the plug under the dash. This is the wire I tested continuity from.

 

DSC01315_zpsa9303fdd.jpg

 

 

Other side of the main harness plug.

 

DSC01317_zps3670803c.jpg

 

What I'm pointing at is where the wire comes out through the other side

 

DSC01320_zps0319b727.jpg

 

Sub harness side of the plug. As you can see, there is something missing.That is where you will plug in the yellow/blue wire from the T connector. You will need this style pin so you can put the wire in there.

 

DSC01321_zps29f43768.jpg

 

Back side of the plug. Just put it in the empty slot

 

DSC01322_zps49d5942a.jpg

 

This is the wire and T connector plug that I pulled from an '84. So cut and plug in yellow/blue wire and connect yellow/green wire to existing yellow/green wire.

 

DSC01323_zps09c21893.jpg

 

 

 

I don't have any pics of the round white plug for the '83/'84 cause I'll need to go to the jy for that but it's the same concept. The only thing different would be the kind of pin that goes in the white plug. Anything else?

The top image is of plug 28 the "squarish plug".  On the main harness side in the 85/86 Factory Service Manual this is plug 28. The last picture is is the early model 720 1980/1983style plug.  Also used in some early build date 1984 trucks.

 

Great pictures guam!

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Dude, I am sending that black gauge holder as soon as I make the swap out! (although it will super glue back together, no roblem.) Awesome and helpful post! The pics are worth a thousand words- each! I need to see a couple more with the connection installed.

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Hey, as long as its one piece cause it'll take me forever to find another one......locally anyway. lol

 

And I will take pics with it installed once I can get the correct pin to slip in there. I think I'm gonna go back to the jy and get the wire and pin from a hardbody, then get a pressure sensor.

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If you look at this pic you can see that the pins come out. Just push that little plastic thing down, pull the wire and the pin will come out with it. Then just put it into your plug. I'm assuming I can get it from a hardbody cause they use these similar plugs. I would try and pull one that is yellow/blue just to keep the wire colors the same.

 

DSC01321_zps29f43768.jpg

 

So now you have this pin and wire and now all you gotta do is find a way to connect it to the yellow/blue wire coming out of the T connector. How I'm gonna do it is use a bullet style connector like this for both wires. Or solder it and heat shrink wrap it.

 

bulletcon.jpg

 

Wire%20splice.solderikng.jpg

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More pics

 

Where I found it

DSC01330_zps5139a2a5.jpg

 

For OlyWa, my skinny ass hand in the hole. lol

DSC01338_zpsa36af3d2.jpg

 

Where the plug should come out. (What Wayno's talking about)

DSC01332_zpse5c6afea.jpg

 

The other white plug is the sub harness to the gauges. I didn't feel like connecting it so I just put them next to each other.

DSC01337_zps7c711d48.jpg

 

An idea of how it will look without the center console. Sub harness will obviously tuck under the console.

DSC01334_zps5f05a2ba.jpg

 

My hand reaching through the radio hole and holding the plug. lol

DSC01341_zps5c80d689.jpg

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My plug was buried behind the heater and ac boxes still taped up with blue tape.  No chance of getting it out.

 

You can get the wires from any 4x4 720 not a Hardbody. I would get the wires with the plug for the sender.  All you need to do is release the 2 wires from the grey oval 4x4 plug and the remove the existing wire from your 520 plug and and in the two 4x4 wires to your plug.  then you have the rubber boot to cover the end of the wire.

 

This is the actual sender plug with the sender

 

DSC01736_zps376785e3.jpg

 

I have several old wiring harnesses around that i use for parts I used wire from these to rewire the plug for the sender as the old wires were brittle from years of heat.

I purchase some of my wiring supplies from:

http://www.vintageconnections.com/

I used the female half of this plug kit on the sender end of the wires.

 

MP2TLLatchingSet_zps323a96f9.jpg

MP2TN Non-Latching Set

T-Configuration. Plain Nylon

2-pin latching 6.3mm

(1/4") spade-based M/F Connector Shell Pair

with 3 each 18-16 AWG

M63/F63 crimp terminals. T-Configuration. Plain Nylon.

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I think I got off easy too. I think I've been getting it REAL easy. My trucks takes a lot of abuse. May not look like it or seem like it but it does. That 4:38 rear end kills me on the freeway. Going 45 in a 65, yeah people don't like me lol. Don't get me wrong though I take real good care of it. 

 

As for the topic, I will check my jy and look at the HB's. I may not find that wire in particular but maybe a wire that utilizes the same pin that I can just slip in the gray plug.

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I have not worked with the Hardbodies a lot with wiring yet but I have a project on the back burner.  I am wiring up a 720 with a Z24I and an Automatic trans out of an 87 Hardbody King Cab.  This will be a challenge as the two harnesses have to be integrated into one,  I do know the 86.5 to 89 Hardbodies did use the grey type plugs.

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