Got too excited cutting wires.... - JeepForum.com
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post #1 of 15 Old 06-18-2021, 05:41 PM Thread Starter
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I have been slowly but surely cleaning my engine bay. It's still a mess. I cut wires to a flat long plastic piece on the passenger side. I thought it was a plug in for diagnostic, I was wrong, had about 6 wires leading to it and about 6 capacitor looking things inside. And are these relays needed that were above that flat plastic thing? They lead to the oil sending unit, which if unclipped, still works (or atleast guage does). Here is a pic for reference.
20210618_193351_1624059453498.jpg


I know that this affects my electric choke on my Weber (nutter bypass), but if I set the choke, it stays idling high, lightly tap once warm and it comes down. Does my electric choke even work? No volts coming out of it. And these relays affect my Intake Heater as well, but I live in FL. And I dont drive it on the 4 40° days we have, lol. When I disconnected them, Jeep drove started and acted normal.

So, how screwed am I? If I just snip off both of those relays?

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post #2 of 15 Old 06-18-2021, 06:59 PM
jbolty
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diagnostic connector, which I'm sure no one on earth still has the one that plus in. The manifold heater relay is triggered by a switch at the oil pressure sending unit so it only runs when the engine is running.

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post #3 of 15 Old 06-18-2021, 07:30 PM Thread Starter
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Originally Posted by jbolty View Post
diagnostic connector, which I'm sure no one on earth still has the one that plus in. The manifold heater relay is triggered by a switch at the oil pressure sending unit so it only runs when the engine is running.
Yeah, in further reading, it seems that the Oil sender wire leads first to one of these relays and then back to the manifold heater?

But I also read on another post that neither of these are needed, as the intake manifold still has the coolant flowing through it, it just may take longer to warm up. But again, in FL, it takes all of 10 mintues, lol. Even our cold days are maybe 50°, can get to 40, but that ain't a Jeep day....

That same post said to just hook up the carb choke to any ignition 12 volt wire, which I'll do. Watch, I'll do it and it will run worse, lol, finally get it what it wants and it probably wont be happy. That'll be my luck, lol
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post #4 of 15 Old 06-18-2021, 11:21 PM
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I pulled the ECM and then cut all the associated wiring on my '90 4.2 but I did not mess with those two connectors. Get the digital copy of the FSM from one of the guys signatures and follow it to see what is removable. There are many splices in the harness with multiple wires leading off to other functions. Most can be cut but like I said, reference the FSM wiring diagrams. I lucked out and the YJ still ran after I got thru stripping two grocery store bags of wire and the ECM.


Good luck!
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post #5 of 15 Old 06-19-2021, 10:42 AM Thread Starter
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Originally Posted by SevenSlotAddict View Post
I pulled the ECM and then cut all the associated wiring on my '90 4.2 but I did not mess with those two connectors. Get the digital copy of the FSM from one of the guys signatures and follow it to see what is removable. There are many splices in the harness with multiple wires leading off to other functions. Most can be cut but like I said, reference the FSM wiring diagrams. I lucked out and the YJ still ran after I got thru stripping two grocery store bags of wire and the ECM.


Good luck!
Good idea, thanks! Yeah, I snip 1 or 2 wires, then keep them in a safe spot away from metal and start the engine before I go further, lol. Then about every 6 wires in I start again, check hazards, turn. Signals, brakes, etc. I'm paranoid.

I just never even thought of the manifold heater, I thought it was a sensor! Lol. Good thing I dont live up North in Winter....
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post #6 of 15 Old 06-19-2021, 11:04 AM Thread Starter
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Awe biscuits, I'm the worst at wiring diagrams, lol.

I can't tell what those 2 relays are on them. Online, some say Fuel Pump is one, manifold heater is the other, others say, others say 1 in sol vac which isnt needed, and other is manifold heater...

Old jeeps.... lol.
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post #7 of 15 Old 06-19-2021, 11:35 AM
Tinker0000
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There is also a temperature switch threaded into the intake manifold to the rear of the carb, for the electric manifold heater/choke system. The ground wire for the manifold heater relay gets its ground through this temp switch.

1984 Jeep CJ7 258 Spring Special edition.
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post #8 of 15 Old 06-19-2021, 11:59 AM Thread Starter
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Originally Posted by Tinker0000 View Post
There is also a temperature switch threaded into the intake manifold to the rear of the carb, for the electric manifold heater/choke system. The ground wire for the manifold heater relay gets its ground through this temp switch.
This makes me think that I never had a Manifold heater, lol. Both wires to it were Purple/Red and lead to same cap. 1 wire lead to one of these relays, IIRC, then orange to the Oil Sending unit. The other purple/red wire lead to one of the diagnostic ports, IIRC.

Now, there has been some serious monkey wiring going on in my Jeep, even before this Monkey bought it, lol. So where I may think, "I messed this up...", it could be that it was always messed up once I bought it, hence it running like "normal", for me atleast. Which is good, I get compliments on how it sounds and runs.
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post #9 of 15 Old 06-19-2021, 02:36 PM Thread Starter
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Welp, I cant let sleeping dogs lay, so I hooked up my choke wire to an Ignition wire, that gets voltage when its running.

Took off the plug to the oil sending unit, and disconnected the relays (checked for power, one does still get power. Jeep ran like normal, and I'm gonna chuck the relays in the glove compartment, and roll around tomorrow like this.

Looked at my manual, found a pic and it was a vague "some years have relays that control engine safety modules", lol, dunno.

I'll report back after a few runs with it, if you see a Green YJ in Saint Pete on the side of the road..... throw a water bottle at me and laugh, lol.
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post #10 of 15 Old 06-19-2021, 04:08 PM Thread Starter
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With some more research the 2 relays seem to be a B+ power latch relay- which only concerns you if you have a computer, It seems to keep the computer running an extra few minutes to get ready for next start up. Think of a Turbo Timer, I suppose.

The next one, still can't confirm what it is, on a 2.5L it is the fuel pump power relay, but we have mechanical pumps.... and I cant find wires to mine. And again, it runs without these relays in? How long can a vehicle run without a fuel pump running?

Sorry guys, just jotting this stuff down for others that may run across this post. Along with trying to answer my own questions.

Here is a diagram for a 2.5L YJ, mine looks exact same....
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Did they happen to wire YJ's before engines put in or something?
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post #11 of 15 Old 06-20-2021, 06:33 AM
brentvo
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If you’re trying to keep the engine bay as simple as possible you can do what I did and I just finished it today. You can completely cut all wires coming out of the firewall directly at the back of the engine, they are all computer wires you don’t need. You can take those relays out too. The wires you keep are the wires coming out of the harness on the driver side beside the brake booster. Even some of those you will scrap. You will also keep the starter relay wires, and the connector underneath that somewhere around the 4x4 vac lines, it’s a 4 wire square connector that gives power to the brake lights/signals/reverse. However what you should do at this connector is cut the ground wire because for some reason the ground wire for the starter relay goes through this harness, just run a short ground wire from the ground terminal on the relay to the block or body.
Take a look below at my diagram but one change I had to make to this was to attach the alternator resister wire (small brown wire) to the orange wire coming out of that harness, it has switched 12v power on it’s own. Don’t connect it how you see in the diagram or else when you turn the key off the ignition coil will keep getting 5v and the engine won’t shut off. Otherwise follow this and you can simplify everything.
You can read my thread which should be just a few under this one still for more clarification about my diagram and the colours.
But the start wire coming out of the harness is green, the ignition on 12v I believe was red or yellow the tach was green and white. Just check with a multi-meter for what’s getting power when.
I took out my manifold heater wire and I live in Canada and it runs fine but if you wanna keep it just tap into the orange wire for 12v with ignition on. Same thing for electric choke.
If you want more pictures or more explanation Il be under my jeep all day today. I’m switching to a manual choke and a manual 4x4 switch to further remove vacuum lines and to be able to crawl ultra slow while still in 2wd.
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post #12 of 15 Old 06-20-2021, 09:22 AM
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I'll add this for the lol's...
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post #13 of 15 Old 06-20-2021, 10:45 AM Thread Starter
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Quote:
Originally Posted by brentvo View Post
If you’re trying to keep the engine bay as simple as possible you can do what I did and I just finished it today. You can completely cut all wires coming out of the firewall directly at the back of the engine, they are all computer wires you don’t need. You can take those relays out too. The wires you keep are the wires coming out of the harness on the driver side beside the brake booster. Even some of those you will scrap. You will also keep the starter relay wires, and the connector underneath that somewhere around the 4x4 vac lines, it’s a 4 wire square connector that gives power to the brake lights/signals/reverse. However what you should do at this connector is cut the ground wire because for some reason the ground wire for the starter relay goes through this harness, just run a short ground wire from the ground terminal on the relay to the block or body.
Take a look below at my diagram but one change I had to make to this was to attach the alternator resister wire (small brown wire) to the orange wire coming out of that harness, it has switched 12v power on it’s own. Don’t connect it how you see in the diagram or else when you turn the key off the ignition coil will keep getting 5v and the engine won’t shut off. Otherwise follow this and you can simplify everything.
You can read my thread which should be just a few under this one still for more clarification about my diagram and the colours.
But the start wire coming out of the harness is green, the ignition on 12v I believe was red or yellow the tach was green and white. Just check with a multi-meter for what’s getting power when.
I took out my manifold heater wire and I live in Canada and it runs fine but if you wanna keep it just tap into the orange wire for 12v with ignition on. Same thing for electric choke.
If you want more pictures or more explanation Il be under my jeep all day today. I’m switching to a manual choke and a manual 4x4 switch to further remove vacuum lines and to be able to crawl ultra slow while still in 2wd.
Thanks! I'll keep this diagram to help me out.

I have an DUI HEI and Nutter bypass, in fact, last night I unplugged the 2 relays AND the ICM, lol. YOLO!! It ran great for about 15 miles. I have electric choke, but understand why some would want a manual, same with 4x4.
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post #14 of 15 Old 06-20-2021, 10:46 AM Thread Starter
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Originally Posted by Flyer58 View Post
I'll add this for the lol's...
LOL, yeah... pretty much...
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post #15 of 15 Old 06-24-2021, 07:04 AM
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I keep forgetting to look at which forum I am in when reading/answering or chiming in on forums. I have an 84 CJ7 which is pretty darn close to the Wrangler emissions and garbage setup. So that relay I told you to find, may not be there. I purchased a wiring diagram from Prospero's Garage back when he had his own website (wiringdiagrams . com, it doesn't work anymore so I broke up the link). The full color diagram was the best thing I could find to both do the nutter and make repairs on other things that had been previously hacked. Prospero's Wiring Diagrams on eBay is where he moved to, I can only suggest to pick up a full color (4 page) wiring diagram for your jeep. 25 bucks for me was nothing compared to what I already spend on upgrades, changes and other (unnecessary crap) stuff I spend on my Jeep. I don't like putting up links that can be broken so just look for "Prospero's Wiring Diagrams" in your favorite search engine and you will find his eBay page. (I am not an advertiser, I just like his product).
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1984 Jeep CJ7 258 Spring Special edition.
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