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The jeep has been installed with GM L94 6.2V8 engine and 6L80E automatic transmission. On the jeep side it has the original ECM, on the engine it has the GM ECM.
Can anyone provide me with the Jeep ECM schematic diagram to resolve the current issue of engine overheating.
I think the Jeep ECM is controlling the cooling fan, not the GM ECM.
Any help wil be much appreciated.

Thanks
 

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They don't publish the wiring schematics for most of the JK years yet, however you can get most of what you need via Mopar Connection Repair Kit and by looking at the service manual.

The Jeep's PCM does control the cooling fan. However, the fan is connected to the engine bay's power distribution center, so it may be very easy to disconnect it from the PDC and control it from the GM's PCM instead. The radiator relay is there, too.

I'll see if I can trace where the PCM sends the signal to the relay, since that likely is the most important part right now.
 

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Okay, as I suspected, the service manual was hand-waving a little bit over what actually happens.

The Totally Integrated Power Module (TIPM) is what has the power circuits that go to the radiator fan control relay. It's on connector C3 as described here: Mopar Connection Repair Kit

But, the TIPM isn't the one really deciding to turn the fan on or off, it's the PCM. The PCM tells the TIPM to do it over the power train CAN bus.

I think in your case, you really don't care about that. If you can intercept the radiator fan control relay at the engine's power distribution center, you're golden.
 

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I don't know about anyone else, when I read DCG's two replies, I thought to myself holy crap! This guy should get a special membership as the SME for systems troubleshooting.

Amazing.

.
 

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Discussion Starter #5
Hey guys thanks a lot for taking time reading my message.
By the way, I work as technician in Dubai, dealing with GMC & Chevrolet Cars and Trucks.
This Jeep came to our workshop cuz it's got the GM v8 engine and automatic transmission.

Many thanks in providing the Mopar Connection Repair Kit link. I will go through on it later today.

Best regards.
 

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Discussion Starter #6
Initially we check the fan motor. It has a integrated control module on it of which a pulse width modulated signal from ECM will be required to control the speed of the cooling fan motor.
 

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Initially we check the fan motor. It has a integrated control module on it of which a pulse width modulated signal from ECM will be required to control the speed of the cooling fan motor.
If you go over to Tech Authority web site, you can buy a short-term subscription. The wiring diagrams might be available via that. Since you are a shop its a good way to get in-depth access to what they offer.
 

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get an 07-13 fan. Its a regular stepped motor fan vs. the pwm fan.

Or you could get one of the flex-a-lite kits(I think its flex a lite) for a hemi swap. Might work for you.

With one of the older fans it shouldnt be hard to wire it up so its constant on with some other triggers for high speed(or a manual switch for high speed). Not as elegant a solution as just letting the PCM control the fan, but might be the only way. Or with a regular fan you could wire it so the GM PCM would control the fan if it outputs directly.
 

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I love the fact that guys are starting to hack into the Jeep PCM and Canbus systems. We are so far behind the curve in this area.
 

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If you go over to Tech Authority web site, you can buy a short-term subscription. The wiring diagrams might be available via that. Since you are a shop its a good way to get in-depth access to what they offer.
I think the link below uses the same wiring diagrams as you get when you pay for access to techauthority. The service manuals aren't available but its better than nothing.

https://techauthorityonlinedemo.extra.chrysler.com/service/repair/wiring/view/classic.htm
 

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I have an 09 and went thru this problem starting several years ago. what I did initially was to wire up a switch and relay to supply power directly from the battery to the radiator fan, which will run it on high all the time. ran it like that for three years. this year I installed a Flex a Lite radiator, fan, and fan controller. it has it's own temperature controller and works great. have put a lot of miles both on and off the road and it maintains the same temperature on both. :beerme:
 

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Discussion Starter #12
The Jeep owner had advise me to get in contact with the people in turnkeyjeep.com

Thanks guys for all your advise.
 

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I have an 09 and went thru this problem starting several years ago. what I did initially was to wire up a switch and relay to supply power directly from the battery to the radiator fan, which will run it on high all the time. ran it like that for three years. this year I installed a Flex a Lite radiator, fan, and fan controller. it has it's own temperature controller and works great. have put a lot of miles both on and off the road and it maintains the same temperature on both. :beerme:
Quick question if I may: I'm putting a Derale fan controller on my JKU '13. While you have a Flex-a-Lite, the problem I have should be the same. Do you get the engine light on and a DTC error code ( P0480 )? If so, do you just live with it, or did you figure how to get around it?

Thanks!
 
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