Radiator Fan Override Switch (The Easy Way)

[fyrfytr1717]

Awesome, that wire can be tricky to track down, even with it pointed out. I hoped it worked out for you!

[Project00XJ]

I did this mod as origionally explained on my 00 xj and it did not work. Put the engine light on. All wiring was done correctly and i used the exact relay as stated. As soon as the wire which actuates the fan relay (blue and pink) is cut the light comes on. If i reconnect the control wire to itsself the light stays off. Has anyone else done this on a 00 or 01? I really would like this to work so any advice would really be great. Thank you!

[03ghosthemi]

Yeah Project00XJ, get this sorted out so you can wire up the fan on mine.

Bill

[Mudderoy]

Originally Posted by Project00XJ

I did this mod as origionally explained on my 00 xj and it did not work. Put the engine light on. All wiring was done correctly and i used the exact relay as stated. As soon as the wire which actuates the fan relay (blue and pink) is cut the light comes on. If i reconnect the control wire to itsself the light stays off. Has anyone else done this on a 00 or 01? I really would like this to work so any advice would really be great. Thank you!

Did you check out the link on post #70? That is how I did my 1998 and it works perfect. (I had the same problem you did at first).

[Project00XJ]

Ghosthemi your in business. I just figured it out. Most people would have quit 5 times by now but i really wanted to do this. So.. my problem was that the blue and white wire in my harness showed power in the run position and ground in the off position. With further testing it was not enough to open the relay. I ran a jumper to the 86 post and it worked perfect. No cel. Lol turns out my vehicle has 2 harnesses that run side by side by the hood hinge on the driver side. I figured my wire to the batt was good enough, so when i was about to be done and put the other harness ( which was pulled out of the way) i said what if, well is was. Turns out both harnesses have a blue whit wire and the other one did the job. I AM IN BUSINESS AND NEED ANOTHER BEER!

[fyrfytr1717]

Originally Posted by Project00XJ

So.. my problem was that the blue and white wire in my harness showed power in the run position and ground in the off position. With further testing it was not enough to open the relay. I ran a jumper to the 86 post and it worked perfect. No cel. Lol turns out my vehicle has 2 harnesses that run side by side by the hood hinge on the driver side. I figured my wire to the batt was good enough, so when i was about to be done and put the other harness ( which was pulled out of the way) i said what if, well is was. Turns out both harnesses have a blue whit wire and the other one did the job.

Good for you for working it through Project00XJ! As I had mentioned in my write up, there are at least 2 DB/White wires, 1 DB/Grey wire, and 1 DB/Yellow wire that run through the engine compartment in that general vicinity and could be easily mistaken for the correct wire, especially in less than ideal lighting conditions. Use the wrong one, and this mod doesn't work properly as the other wires are either the wrong voltage or do not turn on and off with the ignition switch. You really need to make sure that you perform a continuity test between the wire you're planning on using and Pin A2 on Connector 1 in the PCM. This ensures you are using the ST-RUN wire, not some other Dark Blue wire.



I just went out and looked at my XJ and low and behold, in the smaller harness running next to the one containing the DB/Pink wire, there is another DB/White wire. I have yet to test it, but you may have just stumbled across another location for an ignition switched wire! In fact, this looks like it may be the wire that is directly connected to A2 on Connector 1 in the PCM. Jeep likes using the DB/White color code for ignition switched power sources in a variety of locations throughout the XJ. Good find!



In reality, the DB/White wire is not some magical wire that is the only way to make this mod work. It just happens to be the closest ignition switched power wire in the area where you need to tap into the DB/Pink wire. You could just as easily tap into any another ignition switched wire, set up an ignition switched bus bar for this and other accessories, or use a constant hot as Mudderoy continues to suggest. As I mentioned last time Mudderoy made this suggestion though, you need to exercise extreme caution with using a constant hot for this mod. If you inadvertently leave the switch on after shutting down your Jeep, the relay will remain energized and slowly kill your battery.

Additionally, I finally got around to buttoning things back up. I took the piece of corrugated loom that I cut off to access the harness and snapped it back into position. I put the tapped and spliced wires resulting from this mod into a smaller piece of loom, and then wrapped everything back up together with electrical tape as the factory likes to do. Doesn't look perfect, but at least it is all secured and protected once again.

[robhurlburt]

is this exactly the same for a '95?

[fyrfytr1717]

I don't believe so. However, the good news is that from the write-ups I've stumbled across I seem to recall that the earlier models are actually easier to deal with as they don't throw a CEL when you tap into the fan control circuit. It may have been as easy as wiring up a 12V+ lead from a switch directly to the factory fan relay? Don't take my word for it though, hopefully someone that is familiar with the earlier models can lead you in the right direction.

[Mike L]

Originally Posted by fyrfytr1717

I don't believe so. However, the good news is that from the write-ups I've stumbled across I seem to recall that the earlier models are actually easier to deal with as they don't throw a CEL when you tap into the fan control circuit. It may have been as easy as wiring up a 12V+ lead from a switch directly to the factory fan relay? Don't take my word for it though, hopefully someone that is familiar with the earlier models can lead you in the right direction.

On my 96 I wired a 12V+ lead directly to the fan plug from a 12V switched relay and was able to manually control the electric fan. Doing this never caused a CEL to come on. Good luck.

[XJRunner]

on my 87 i run a wire with an inline fuse to a switch than directly to the fan

[fyrfytr1717]

Originally Posted by Mike L

On my 96 I wired a 12V+ lead directly to the fan plug from a 12V switched relay and was able to manually control the electric fan. Doing this never caused a CEL to come on. Good luck.

I was hoping somebody had wired up a fan override on their early model in the same spirit as this thread, controlling the factory fan circuit via a switch as opposed to wiring in an additional circuit to power the fan...

Originally Posted by XJRunner

on my 87 i run a wire with an inline fuse to a switch than directly to the fan

And you haven't fried your switch yet? Must be a pretty stout switch to be holding up to powering your fan without use of a relay.

[robhurlburt]

Originally Posted by fyrfytr1717

I was hoping somebody had wired up a fan override on their early model in the same spirit as this thread, controlling the factory fan circuit via a switch as opposed to wiring in an additional circuit to power the fan...

thats what i want. i want the fan to work exactly like normal, but be able to turn it on a little early if i feel like it. If i see a big climb, and i know by the time i'm at the top i will be over heating, it would be nice to turn the fan on at the bottom of the hill.

[robhurlburt]

looks like this has everything for the 92-95 system

http://www.jeepforum.com/forum/f11/a...p-pics-811703/

[fyrfytr1717]

Well that ^^^^ was a long, confusing read. From what I gathered, on '95 and earlier models, you can just splice a new wire into the DB/Pink wire, run it to a switch, and then connect the other side of the switch to ground. Much easier.

It was interesting to see my wiring diagram included in that thread as well. I don't frequent JeepForum much. Thanks for the credit MrJCRod, "someone on another forum"...

[robhurlburt]

Originally Posted by fyrfytr1717

Well that ^^^^ was a long, confusing read. From what I gathered, on '95 and earlier models, you can just splice a new wire into the DB/Pink wire, run it to a switch, and then connect the other side of the switch to ground. Much easier.

thats what i gathered. there were also schematics to run a lighted switch, a 3 position switch etc.

hope you don't mind the jeepforum link, i thought it would be helpful to someone who had a pre 96 and stumbled across this. now this covers 91-00