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Basics of the 4x4 system on the Jeep Patriot?

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#22 ·
Fredom Drive 1 Youtube Video Not correct

todde702 said:
Mechanically, here is how it is connected. The front transaxle contains an open differential. The front drive axles are connected to this differential (via spider gears) and power is sent to both front wheels. Being an open differential, if one wheel starts spinning, then all power will go to that wheel (both FDI and FDII models have electronic brake lock differentials, which will active the normal brake calipers to help alleviate this open diff flaw, but let's not muddy the waters on how power is sent).

Bolted to the side of the transaxle is the PTU unit which sends power to the rear differential. The right side front axle passes through this unit but has no mechanical connection for power to it. The PTU is connected to the differential carrier in the transaxle. So if the transaxle differential carrier is spinning, then power is sent to the rear differential. Even when driving on dry roads, power is sent through the PTU, down the driveshaft to the rear differential.

The rear differential, also an open differential, has an electronic clutch between the driveshaft and the rear diff input pinion. The computer can cycle the clutch from full off, to full on depending on what the sensors and/or 4x4 switch REQUEST. This is a key word to understand. The 4x4 switch is a request to the computer to split the power 50/50, but in certain situations, the computer can ignore or over-ride that request.

Now, if both front wheels are stuck and unable to turn, no power will go to the rear differential. You must be able to get at least one front wheel spinning before any power will be available to spin the rear wheels.
Click to expand...
Thanks for the great info.

http://www.jeeppatriot.com/forum/showthread.php?p=1165186#post1165186
This shows the drive shaft not spinning in Front Wheel Drive operation.
Must be wrong.

HKS
 
#23 ·
One of the biggest misconceptions of the MK 4x4 system is that it requires front wheel slip before the back end engages. This is simply not true at all.

Todde702 is correct that the driveshaft is always sending engine power to the rear wheels, and it's the clutch (electronically controlled) that either engages or disengages. This happens very quickly.

Here is a video with my compass (front end in the air, rear on the ground 4x4 fuse pulled, so no 4x4)


Driveshaft is spinning, but clutch isn't engaging.

Even on dry pavement the system will send power to the rear under heavy acceleration or cornering or whatever to enhance handling.

I know this because I've found a fuse I can pull that disables the 4x4 (basically the ECC clutch) and its very obvious the back end isn't receiving power. Good example is full throttle takeoff on dry pavement, with the 4x4 disabled the weight shifts to the back, front end lifts up a lot, exactly like a fwd vehicle.

Put the fuse back in do the exact same thing, vehicle stays more level and takes off, because the back tires are receiving power.

Regardless about what Jeep's videos state I've had MK's for 6 years and tested/played around with the 4x4 system lots.

I"m probably biased but it's one of the best awd systems out there, especially for snow and slippery roads.
 
#24 ·
ECC Fuse

Tyler-98-W68 said:
One of the biggest misconceptions of the MK 4x4 system is that it requires front wheel slip before the back end engages. This is simply not true at all.

Todde702 is correct that the driveshaft is always sending engine power to the rear wheels, and it's the clutch (electronically controlled) that either engages or disengages. This happens very quickly.

Here is a video with my compass (front end in the air, rear on the ground 4x4 fuse pulled, so no 4x4)

http://www.youtube.com/watch?v=m-K0SakcGHk&list=UUh3f8Fsq-Q7dU6XwAcvyOSw

Driveshaft is spinning, but clutch isn't engaging.


Even on dry pavement the system will send power to the rear under heavy acceleration or cornering or whatever to enhance handling.

I know this because I've found a fuse I can pull that disables the 4x4 (basically the ECC clutch) and its very obvious the back end isn't receiving power. Good example is full throttle takeoff on dry pavement, with the 4x4 disabled the weight shifts to the back, front end lifts up a lot, exactly like a fwd vehicle.

Put the fuse back in do the exact same thing, vehicle stays more level and takes off, because the back tires are receiving power.

Regardless about what Jeep's videos state I've had MK's for 6 years and tested/played around with the 4x4 system lots.

I"m probably biased but it's one of the best awd systems out there, especially for snow and slippery roads.
Click to expand...
Good info. You verified that the FreedomDrive-I YouTube video is incorrect since it shows the driveshaft not spinning in front wheel drive. It spins all the time when driving FWD or 4WD.

Could you tell me where the fuse is and how is it labeled?
Thanks

HKS
 
#25 ·
If you look in you owners manual, it lists a description and a diagram of where the fuses are located.

Fuse #35 is green, it is the Antilock Brake Pump, pulling that disables the ABS/ESP system completely.

Fuse #34 is pink, it is "anti-lock brakevalve"

Fuse #34 will disable the ECC, but the down sides are

1. Your speedometer will no longer work
2. On CVT equipped modes it shifts a bit funny and revs higher than normal
3. If you drive like this for a long enough period of time the check engine light comes on.

After replacing the fuse, the check engine light goes out after a few trips.

I don't recommend doing this on a regular bases I've just done it while testing things out.
 
#26 ·
Great Patriot Info

Tyler-98-W68 said:
If you look in you owners manual, it lists a description and a diagram of where the fuses are located.

Fuse #35 is green, it is the Antilock Brake Pump, pulling that disables the ABS/ESP system completely.

Fuse #34 is pink, it is "anti-lock brakevalve"

Fuse #34 will disable the ECC, but the down sides are

1. Your speedometer will no longer work
2. On CVT equipped modes it shifts a bit funny and revs higher than normal
3. If you drive like this for a long enough period of time the check engine light comes on.

After replacing the fuse, the check engine light goes out after a few trips.

I don't recommend doing this on a regular bases I've just done it while testing things out.
Click to expand...
Thanks, very much.
It is good to know this fuse information.

One more question: When pulling the 4WD lock, can one hear slight sound as the ECC engages and dis-engages (if you were under the car near the ECC).
HKS
 
#28 · (Edited)
ECC Thanks

Tyler-98-W68 said:
I'm going to say no you won't hear it. I haven't ever heard mine before.
Click to expand...
Thanks again Tyler-98-W68.

I will now leave this topic alone for a while and I really appreciate your experience and knowledge of the Patriot 4WD train.

HKS

P.S. I will report back much later after I try the Steelman Wireless ChassisEAR on the ECC.
 
#29 ·
I think I follow what you want to do, you want to know when the ECC is engaging and disengaging, I like that idea too, I wonder if there was a way you could tap into the canbus system and read the voltage or something else.

Something similar to this.....

 
#30 ·
ECC Test

Tyler-98-W68 said:
I think I follow what you want to do, you want to know when the ECC is engaging and disengaging, I like that idea too, I wonder if there was a way you could tap into the canbus system and read the voltage or something else.

Something similar to this.....

http://www.youtube.com/watch?v=uOWGq1B8C84
Click to expand...
Tyler, you are correct. The ECC is just one of the suspects I am trying to confirm or eliminate. The dealer will never find this bearing rattle since it only happens after driving 90 miles in hot weather.

Bearing rattle is loudest when going uphill and then backing off on the gas pedal in hot summer weather. In other words, during a temporary no load drive train condition while transitioning between power and coast. I think it is there all the time but gets louder as described above.
The other suspects are, carrier bearing, PTU, transmission, CV joints front or rear. It sounds like marbles swirling in a glass jar. One might suspect that somewhere the oil is the wrong viscosity.

HKS
2014 Patriot 6 speed auto, 2.4L Latitude. over 4000 miles now.
 
#31 ·
HKS said:
Tyler, you are correct. The ECC is just one of the suspects I am trying to confirm or eliminate. The dealer will never find this bearing rattle since it only happens after driving 90 miles in hot weather.

Bearing rattle is loudest when going uphill and then backing off on the gas pedal in hot summer weather. In other words, during a temporary no load drive train condition while transitioning between power and coast. I think it is there all the time but gets louder as described above.
The other suspects are, carrier bearing, PTU, transmission, CV joints front or rear. It sounds like marbles swirling in a glass jar. One might suspect that somewhere the oil is the wrong viscosity.

HKS
2014 Patriot 6 speed auto, 2.4L Latitude. over 4000 miles now.
Click to expand...
Send me a PM, your marbles rolling in a can sound is something i'm experiencing but I think i've narrowed it down to CV axles, i'd like to speak more on the topic.
 
#32 · (Edited)
ECC Delay Time

Tyler, this is just supporting info for your research on the MK 4x4.

I did a test yesterday on a hill in a cow pasture (no pies). A 4x4 owner/expert was with me and said FWD would not make it up the hill of wet grass. It rained an hour ago.

First test: I headed uphill with 4W lock and it climbed right up and no noticeable tire slip.

Second test: I tried it again with 4W lock off and the rear tires would spin for one second, then the computer engaged the rear diff and wheels.

This is what I wanted to know and a wet uphill cow pasture test may be better than a snow test.

HKS



Tyler-98-W68 said:
One of the biggest misconceptions of the MK 4x4 system is that it requires front wheel slip before the back end engages. This is simply not true at all.

Todde702 is correct that the driveshaft is always sending engine power to the rear wheels, and it's the clutch (electronically controlled) that either engages or disengages. This happens very quickly.

Here is a video with my compass (front end in the air, rear on the ground 4x4 fuse pulled, so no 4x4)

http://www.youtube.com/watch?v=m-K0SakcGHk&list=UUh3f8Fsq-Q7dU6XwAcvyOSw

Driveshaft is spinning, but clutch isn't engaging.

Even on dry pavement the system will send power to the rear under heavy acceleration or cornering or whatever to enhance handling.

I know this because I've found a fuse I can pull that disables the 4x4 (basically the ECC clutch) and its very obvious the back end isn't receiving power. Good example is full throttle takeoff on dry pavement, with the 4x4 disabled the weight shifts to the back, front end lifts up a lot, exactly like a fwd vehicle.

Put the fuse back in do the exact same thing, vehicle stays more level and takes off, because the back tires are receiving power.

Regardless about what Jeep's videos state I've had MK's for 6 years and tested/played around with the 4x4 system lots.

I"m probably biased but it's one of the best awd systems out there, especially for snow and slippery roads.
Click to expand...
 
#33 ·
Sorry to return to the 4WD switch. My 4WD! light has come on and stays on. No corroded wires between cab and fuse box, nothing stuck under 4WD switch, but I did notice there is zero ohms electrical resistance at the 4wd switch when it is activated, and 3.9 - 4V measured at the switch when it is not activated. Would this amount of electrical bleed through at the 4WD switch cause the 4WD! to remain on? thank you in advance for your reply
 
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