eFan timer time

Time to install a fan time on the 2000 for the heat soak issue. It has been flaring up a lot lately, even with DEI fuel wrap kit and a LeBaron hood vent. There are many, many write ups, I'm reading through them now, but my wiring knowledge on this is testing me.

I'm wanting to use a similar timer that I have for my dash cams, as I love the timer and its adjustability. https://www.amazon.com/gp/product/B00PD65UGA/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A2C3OEB0RE1BRS

I'd like to hook up the timer to a momentary switch on the dash, that when pushed after I cut off the Jeep will trigger the timer to run the eFan for 3 mins. Here is where my knowledge gets fuzzy, it's been a long time since I went this far with 12v.

I know the PCM uses PWM to activate the stock fan relay with a ground trigger, and any modification not done correctly will set off a CEL, or cook the PCM worst case. I need to add a diode to keep power flow out of the PCM and isolate the new timer circuit. I am just not wrapping my head around the diode size and where to place it.

My plan is to take advantage of as much factory wiring as possible. I would add a new fused relay that is triggered by the timer to run for 3 mins, and wire that in parallel to the original wiring. Where to put the diode, and what size to use?

What size/placement of diodes does everyone suggest, or have used?

I use small 3-amp, 50 volt diodes to isolate the fan trigger circuit.
https://www.radioshack.com/products/200a-barrel-diodes

The amperage rating is low because only the relay trigger passes through it, not the full fan power.

I have used this timer for many years.
https://www.flickr.com/photos/lwade/sets/72157617434915718/
It's the only thing I have tried that always works to eliminate the hot soak problem, when I remember to use it.

Some people have used the timed relay from the headlight switch. As in, go get another one from the junkyard / parts store, and rig it to the ignition power

C'mon now!!
Imperial electric #226208.
U wanna know how to wire it pm me.
Sheez.

And yeah, it's not "made in USA".
However, its just a relay and if you plumb it and wire it properly it'll work better than any timer.
You won't use any of the oem relays, you'll isolate them.
And you don't have to do anything inside the jeep, it's a no brainer.
I'm having problems w/ running to cold now but it could be adjusted, it's gonna get toasty warm around here soon.

Transpoquick said:

C'mon now!!
Imperial electric #226208.
U wanna know how to wire it pm me.
Sheez.

Click to expand...

Easy except for where to put the temperature probe. It needs to be in the upper radiator hose, in an adaptor like this.
https://www.amazon.com/Aluminum-Temperature-Sensor-Adapter-Silver/dp/B00FY3A2PG
Imperial Electric 226208
https://trendyas.wordpress.com/2015/04/06/imperial-thermostatic-fan-control-adjustable-226208/
This is simpler than adding a timer?

lazyxj said:

Easy except for where to put the temperature probe. It needs to be in the upper radiator hose, in an adaptor like this.
https://www.amazon.com/Aluminum-Temperature-Sensor-Adapter-Silver/dp/B00FY3A2PG
Imperial Electric 226208
https://trendyas.wordpress.com/2015/04/06/imperial-thermostatic-fan-control-adjustable-226208/
This is simpler than adding a timer?

Click to expand...

Negative you'll drill and tap the thermostat housing, and yes much easier.
Sheeeeeeeeez.

Transpoquick said:

Negative you'll drill and tap the thermostat housing, and yes much easier.
Sheeeeeeeeez.

Click to expand...

Not sure what thermostat housing you are using, the ones on my XJs don't have suitable spots thick enough to drill and tap, that I would trust.
Got any pictures of where you have done this and had it hold up?

I'll post a picture of that.
In the near future, have not done that on here yet so gotta figure that out.
Give me some space yo!

Transpoquick said:

I'll post a picture of that.
In the near future, have not done that on here yet so gotta figure that out.
Give me some space yo!

Click to expand...

Interesting, you say it's no big deal to drill and tap the thermostat housing yet you have never done it.
Sheeeeeeez

lazyxj said:

Interesting, you say it's no big deal to drill and tap the thermostat housing yet you have never done it.
Sheeeeeeez

Click to expand...

lol Exactly, not helpful at all, since I asked about a diode placement, not a kit.

I have my plan to add a separate relay, triggered by a timer that I have previously used in 3 locations on my vehicles, to run for 3 mins. I have tossed up the idea about a headlight timer to control it, but I work with only 30mins to get in and out of the local pull yards and they do not let you in 30 mins before closing, so obtaining one is difficult.

Below is the most basic diagram I can make on the work PC; sorry. Should I install the diode on the fan side of the new relay to isolate it?

lazyxj said:

Interesting, you say it's no big deal to drill and tap the thermostat housing yet you have never done it.
Sheeeeeeez

Click to expand...

Bwah, where in any of the post I made on this thread did you read "I never drilled and tapped my housing"?.
I said I never posted a picture, your reading comprehension skills are lacking.
Your not going to see it now any way because I can't post attachments.
Won't matter because your basic hand tool skills are obviously lacking as well.
:rof:

CarbonXJ said:

lol Exactly, not helpful at all, since I asked about a diode placement, not a kit.

I have my plan to add a separate relay, triggered by a timer that I have previously used in 3 locations on my vehicles, to run for 3 mins. I have tossed up the idea about a headlight timer to control it, but I work with only 30mins to get in and out of the local pull yards and they do not let you in 30 mins before closing, so obtaining one is difficult.

Below is the most basic diagram I can make on the work PC; sorry. Should I install the diode on the fan side of the new relay to isolate it?

Click to expand...

Btw, you can't post attachments either from what I can see.
Good luck with the diode thing, that's a interesting drawing.
If you can do that, why can't you install it? stick to the vents in the hood:laugh:

Tranny stop trolling my thread and stop writing like a 10 year old. Thank you for your suggestion though.

I believe placing a diode on the line from the PCM would keep power away from it. Would I need another on the new Bosch style side that I'm adding?

lazyxj said:

Not sure what thermostat housing you are using, the ones on my XJs don't have suitable spots thick enough to drill and tap, that I would trust.
Got any pictures of where you have done this and had it hold up?

Click to expand...

https://www.google.com/imgres?imgur...Y8evTAhUi2oMKHcKyC9cQMwgvKAowCg&iact=c&ictx=1

Ahh, Google.
That's a suitable location for 1/8-27 temperature probe, that's npt pipe thread if your confused about the numbers.

CarbonXJ said:

I believe placing a diode on the line from the PCM would keep power away from it.

Click to expand...

If you plan on adding a new relay, there should be no need for a diode, since there is no connection to the PCM.
Running the output of the new relay directly the + side of the fan should not cause back feeding problems.
If you are using the Factory fan relay, then a diode is needed on the relay's control wire, to prevent back feeding into the PCM.

Not sure why a link to fyrfytr1717's thread on installing an auxiliary fan control relay without setting a check engine light hasn't been posted up yet.

http://www.naxja.org/forum/showthread.php?t=1025399

Once the relay is installed, you can control it however you like.

you could also use a dakota digital fan controller. Its completely programmable for how much time it stays on after ignition is turned off.

I still don't understand why anyone would want to control a fan that cools their engine w/ time instead of temperature.
It's odd, what if the engine temp doesn't come down enough in the time that's set?, I must be missing something.
Sorry op I'm "hijacking" your thread.

Transpoquick said:

I still don't understand why anyone would want to control a fan that cools their engine w/ time instead of temperature.
It's odd, what if the engine temp doesn't come down enough in the time that's set?, I must be missing something.
Sorry op I'm "hijacking" your thread.

Click to expand...

With the engine not running it would be pretty much impossible to reduce the coolant in the block with only a fan. It's more to help remove ambient heat to possibly reduce the chance of injector heat soak.