Hey guys - new Jeep owner here and have an ecm question.

[SREAD]

Was out driving around town with a/c switched off. Ambient temp was 88. Had to stop for a red light and while stopped, I watch coolant temp climb steadily from 192 to 221. Never heard or had any indication the cooling fan came on. The light changed and I was able to start moving again and once on the freeway the temp finally started falling and fluctuated between about 185 and 195. After I got off freeway , turned on a/c and temp would hold about 192 , and I could hear the fan running. Anyways, got home and decided to test if fan was functioning without a/c running. Let it sit there and idle and again the temp climbed steadily to about 221 but this time I finally heard the fan start to run slowly and the temp began to decrease gradually.
Obviously, the ecm doesn't command fan to come on til appx 220 degrees and like most modern cars uses a soft start and pwm control for the fan now.
My question is, is there any way to change those parameters and make the fan start sooner? Do any of the tuners have that capabilty? Thanks!

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[River2016]

the TD3 may have it, and the Diablo i3 and T2 offer a parameter for target coolant temp. Theres no traditional on/off control with the JL, the pcm simply targets a coolant temp and works the fan to get it to stay there.

-from jl forum

 

[SREAD]

Thanks for the quick reply! Do you know if it is true now that any tuner or re-flash of the engine parameters leaves a "footprint" and FCA may void the warranty?

 

[willys 41]

Here is what I discovered and what I am working on
This is how the cooling system works or not working
The thermostat opens at 190 degrees
The cooling fans comes on at 1/4 speed at 221 and will only go fulls speed at 231 degrees
I have been trying to get control of the cooling system by adding a pusher fan on the condenser put this is what I found
Most cars including the jeep JK the condenser is mounted 1/4 to 1/2 in. from the radiator
On the Jeep JL the condenser is about 1 1/2 in. away from the radiator
I can get the pusher fan to shoot air though the condenser at 150 MPH put as soon as it hit the radiator the air blows out the large gaps between the condenser and radiator and NO air going through the radiator
Next step was to close the caps between the condenser and radiator to force the air through the radiator
So now with the gaps closed off I have about 15% of the air going through the radiator and the rest of the air is blowing back though the condenser and trans cooler
Two things wrong here. The gap between the condenser is to large and the radiator WILL NOT allow free flowing air to pass through it whether you are pushing air at 150 mph with a fan or diving down the road at 60 /70 mph and that is why you see a 30 to 40 degree swing in the coolant temps. You would thing driving down the road you are getting air passing through the radiator put you are getting very little to none until the fan kicks in and sucking the air through the radiator
I ordered a Mishimoto radiator (back ordered) it looks to have a more open core that will allow more free flowing air to pass through
I will install the Mishimoto and see how it goes
And NO. The radiator is not plugged in any way inside or out side. The jeep did this from day one . New in 2020
The Engineers got this one wrong . I also found out later that the Engineers struggled with cooling system on the gladiator trying to keep it cool with a high towing capacity

UPDATE
The new Mishimoto radiator is installed . NO difference in cooling
The real problem is controlling the fan and I think I just found the answer
RPM Extreme Jeep JL PWM FAN CONTROLLER

Specs on JL PWM FAN CONTROLLER

http://www.rpmextreme.com/Product/311/Jeep-JL-PWM-FAN-CONTROLLER.aspx

NORMAL CANBUS OPERATION:

When the engine is running the PWM fan will run at a low Idle speed (15%).

When the module reads the engine temp it will command the fan to the desired %.

Fahrenheit

199 degrees = 30%

205 degrees = 50%

212 degrees = 75%

218+ degrees = 100%

You can also order it with a full speed bypass. Meaning you can turn the fan on full speed at any time.

Jon Schaefer has been building these for years for the JK and is now making them for the JL
I will receive it today and see how it works


UPDATE
Just got back from a 60 mile round trip with up and down hills
One hill is about a mile long and fairly steep
Max temps on uphill clime WITH PWM module
Coolant 203
oil temp 206
Trans temp 195

Going down hill after 2 minutes
coolant temps 185
Oil temps 188
Trans temps 188 to 190

freeway driving 70 MPH
coolant temps 188 to 192
oil temps 188 to 190
trans temps 190 ( Note / The trans cooler I believe has a 190 degree thermostat so you will always see about 190 )

BEFORE the PWM module I would see going uphill
Coolants temp rise to 221 fans kick in at bout 15% and then if the hill was a long one go to 231 before the fan kicked in at about 75% . I have seen temps as high as 234
Oil temps would get as high as 225
Trans temps would hit 206

The JEEP JL PWM FAN CONTROLLER is a keeper
Now I need to add one to my wife's stock Rubicon

 

[SREAD]

Yeah, the effect you noticed is why a puller fan is just about always preferable to a pusher style. The problem I see is that they wait way too long to get the fan up to speed. Experience tells me it is much easier to keep a cool engine cool than to try and cool down a hot engine.
That fan controller looks like a possible solution - if it will work on the Jt. I wonder how it taps in to the can.

 

[willys 41]

From what I have read this is nothing new
I have see PWM fan set ups for other trucks and cars
RPM Extreme programs one just for jeeps JK and JL

 

[willys 41]

UPDATE
Just got back from a 60 mile round trip with up and down hills
One hill is about a mile long and fairly steep
Max temps on uphill clime WITH PWM module
Coolant 203
oil temp 206
Trans temp 195

Going down hill after 2 minutes
coolant temps 185
Oil temps 188
Trans temps 188 to 190

freeway driving 70 MPH
coolant temps 188 to 192
oil temps 188 to 190
trans temps 190 ( Note / The trans cooler I believe has a 190 degree thermostat so you will always see about 190 )

BEFORE the PWM module I would see going uphill
Coolants temp rise to 221 fans kick in at bout 15% and then if the hill was a long one go to 231 before the fan kicked in at about 75% . I have seen temps as high as 234
Oil temps would get as high as 225
Trans temps would hit 206

The JEEP JL PWM FAN CONTROLLER is a keeper
Now I need to add one to my wife's stock Rubicon

 

[SteveInOrlando]

Thanks for the quick reply! Do you know if it is true now that any tuner or re-flash of the engine parameters leaves a "footprint" and FCA may void the warranty?

I can confirm that they do. They set a background code that doesn't display a CEL. I don't remember the number, I removed it from the available codes on mine, but I have HP Tuners and the replaced chip in the ECM makes it obvious it has been modified.

You can remove the BUS style tuners before going to the dealer, but the code will still be set. You need to have full admin rights to remove the code.

 

[SREAD]

UPDATE
Just got back from a 60 mile round trip with up and down hills
One hill is about a mile long and fairly steep
Max temps on uphill clime WITH PWM module
Coolant 203
oil temp 206
Trans temp 195

Going down hill after 2 minutes
coolant temps 185
Oil temps 188
Trans temps 188 to 190

freeway driving 70 MPH
coolant temps 188 to 192
oil temps 188 to 190
trans temps 190 ( Note / The trans cooler I believe has a 190 degree thermostat so you will always see about 190 )

BEFORE the PWM module I would see going uphill
Coolants temp rise to 221 fans kick in at bout 15% and then if the hill was a long one go to 231 before the fan kicked in at about 75% . I have seen temps as high as 234
Oil temps would get as high as 225
Trans temps would hit 206

The JEEP JL PWM FAN CONTROLLER is a keeper
Now I need to add one to my wife's stock Rubicon

Hey thanks for the report - how was the install? how did you tap in to the can bus?

 

[willys 41]

More info
The plug that you see you pull back the tape on the loom to get to the wires

 

[SREAD]

Got it - Thanks! Unfortunately, this looks like it is one of those mods that is best postponed till you no longer care about warranty protection.

 

[willys 41]

Yes. Maybe. Put I am done with the dealer
Every time I would take it in they would tell me theirs nothing wrong with your jeep
I don't even take in in for my free oil changes any more. I got tired of cleaning up there mess
The last straw was when I took it in with a brake problem and was told it was normal
I told them it was not normal and as I walked out I said I WILL FIX IT MYSELF. And I did
MUSHY BRAKE SYNDROME

https://www.jlwranglerforums.com/forum/threads/the-wrangler-mushy-brake-syndrome-finley-fixed.82912/

With the ABS bleed (most important part) and the Teraflex Delta brakes I have brakes that most jeep owner only dream about

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