Comanchero87

Check out the discussion we just had. Search Elecitric Fan switch mod. I just did this. They explained how to do it a couple different ways. I used a second relay and switch but you can use the existing relay. Sounds like they ran a jumper from your fan relay to an ignition source. If you find it and disconnect it you will have it back to stock hopefully. Read the above mentioned for wiring the switch.

My second relay is tapped directly into the red wire coming directly from the fan not from the sensor. That way the relays act independently from eachother I believe. Since the KC relay is just sitting there all hooked up with no KC light to operate I figured It was alot easier then trying dig through the rat nest of relays on my fender. Its wired up for 4 switches in the cab that until now had no function. So as long as its not going to fry anything if it does magically decide to turn itself on one day I'm going to just leave it alone and admire how when I hit the switch it turns on engine on or off. It blows a nice stream of cool air into the engine compartment. Its like under hood air conditioning while wrenching on hot days.

before After....a little better. They are new used connectors. The electrical tape makes them look ugly. Before the ground mod after. Still need the correct size split loom. Napa had 2feet of 3/4 for 5bucks....ya no thanks. I bought 1in at 99cents a foot. Just to see but its way to big. The actual splice location after the mod. Notice the wire going from the bottom section of the Incoming C101 harness and the upper outgoing c101 harness. This is where it ends up after you cut about 6inch section off of the 3 wires on the lower section and a couple off the upper. Its hard to tell from the pic but its about 4-6inches up the harness from the MAP.

Check your manifold bolts for tightness. I don't know on the HO but my renix seemed liked they were hand tight.

Just for the Record I live in Hawaii and the temperature never drops below 70 and regularly is above 90. Ive never heard the elec fan kick on for the 3yrs ive owned this truck.

Thats what i was scared about in the first place. I got so many conflicting responses I just did it. I have the separate KC light relay connected directly into the fan circuit. Should I change it? The separate relay is fused.

So I just left everything hooked up. spliced in a direct ground on the fan. then attached switchable power into the fan power wire Works like a charm. Thanks guys.

$5.20 :banana: Crap I'm not winning any contest here :mad:

:waving: Thanks for all the help Cruiser. Would have been lost without your guys help

So I started digging after the MAP for the other connection. It is after the C101 and before where the split loom sheathing T's a bundle heading downward. So cut the single wire heading toward the C101. And Hooked up the 3 green with white wires coming from the MAT,CTS,TPS and hooked them up with the 3coming from the MAP,?,? And ??????? Steady even jiggling the harness. Thanks again guys, hope this makes a nice addition to the search option on this site.

Reviving this old post. Attempting this process. Should there be a good flow through the bottle return line into the bottle with cap off on its way to operating temp? I can't get the bottle to boil. Ive got it up to operating temp but it just over flowed from the bottle once I turned it off. I still hear a dibbling sound like the water is running back into the engine no sucking sound except the first time when the bottle ejected all is coolant.

I was planning on cutting the wires behind the fan harness on the fan side. I was going to use a existing switch and relay which is already wired to the front of the truck and to the cab for the non existent KC lights. Wanted to do it this way :clapping: To the sensor? not to the fan itself? Wouldent that just energize the sensor? I'm a plumber not a mechanic or electrician. Slowly getting more familiar with automotive electrical with your guys help. :help:

By the way the Multi Meter is from Napa 32bucks. Its the Best investment a budding comancheiac can make. If you own a renix Jeep buy one you are going to need it.

Cleaned up C101 harness and eliminated the TPS resistance problem. Adjusted TPS. Which relieved the MJ of many of its illnesses. Installed new fuel filter. Started working on hooking up electric fan to cab mounted switch.

I have a KC light relay with switch and fuse already in the cab. My electric Fan Is not working like I think it should or when it should. Ive already disconnected the harness and stuck the the Ground and positive jumper from the relay in the harness and checked to see if the relay would operate it which it does. Now my question is if I hard wire the Fan to the relay and leave the harness disconnected will this negatively affect operation of other things? I know it connects to the relay on the fender which tells it to kick on from the radiator sensor and ac motor. But will leaving the connection at the fan open affect anything else? I live in Hawaii and believe the engines temp should have that fan running all the time. Ive got idiot lights until the new cluster comes in the mail. Ive taken temps at the intake manifold with a digital meat thermometer have had readings above 210 while idling up in the garage. New T stat along with a new pressure bottle and full flush in a week when the parts come in. Ive read the fans are possessed and read alot about people hooking up a switch in the cab. Couldent find anything describing the process.

Was a dirty c101 connector, Bad ground to TPS, MAP, MAT. Modified ground harness and cleaned the C101 and fixed the problem

C101 cleaning/Ground harness mod/ adjusting TPS, solved the problem for me. No more high idle when it gets hot, no popping through the intake. For the people searching in the future.

C101 connector/ ground harness modification/TPS adjustment. Fixed the problem. Just for the people who will search this and only find the question with no answers.

Ya I was getting some 1.2ohm readings so I squeeze the harness after the MAP and right back down to .9ohms. So Looks Like I should complete the mod to keep it from jumping up and down. Have to get some better electrical solder. I'm Using my plumbing solder and Flux and is not working so great. I guess thats what happens when you put a plumber on a electrical job. Reset the TPS to .83volts took for a test drive. No more high idle. :clapping: The MAT is showing 12ohms on a hot engine same with the Engine temp sensor. O2 has 12.7 volts, and jumps between 1 and 5 volts on a idling engine. The MAT and ETS seem out of spec. :mad: Ive got a new IAC on the way along with new Vac tree and thermostat. I should have bought the MAT and ETS also. Next parts binge I guess.

So after jiggling the harness and c101 got it down to here. So I split the harness. First connection I found was this. Fuel injector grounds I suppose. Kept working up from the MAT sensor ground and found this Duck taped connection So I cut the crimp out and soldered the connections And wall ah. I guess I don't need to modify it the rest of the way. Dident read the last posts before I went digging PO loved rat nesting the engine bay I guess Next electrical project Thanks fellas

Update key off. 5ohms at "B" on TPS, 6ohms at MAT.

Ok so I will wait and see if this info changes before I attempt to Modify my ground harness. Yesterday went through and refreshed the firewall ground, the dip tube ground, drivers side tail light ground, c1o1 connector and added a ground from the battery strait to the fender. My c101 on the right side has 3 pins on the second row up. After cleaning I noticed the body side of the harness dident seem to have contacts for the 3 pins located on the second row. Anyone feel like pulling their c101 to see if I have a problem there. Also looking through other posts I noticed I have no transducer after the egr valve. Is this because its an 87? Should I have one? As for the Key off. I get 1ohm with key in off position. So I'm not really sure if this info is correct.

So I have a 14ohm reading on the multimeter with key on TPS connected. Been trying to find the write up on the Ground Harness Modification but came up empty. Every search just comes back with showing that if the ohms are higher than 1 then ground harness modification is required. Nothing about actually preforming it. Is it just splicing in a alternate ground on the "B" terminal wire? Thanks guys

here's another one. I have the same issue. Ive been searching this site for 1yr trying to find a topic that actually ends with a solution to this problem.

Here you go Exxon Image Not Found Image Not Found Image Not Found