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Driveline Clunk and PSM Relay


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I need some help with my 06 CS(145k miles).

 

I am having a clunk in my driveline and Im trying to isolate the issue.  The clunk happens under a specific condition when I am slowing down from over 40 MPH.  For example, I begin to slow down for a red light ahead.  I let off the gas and brake slightly.  I slow down to say 15-25 MPH.  The light will turn green and I give it some gas.  Then I get a clunk in the driveline.  It sounds like its coming from the front axle or the tranny/transfer case.  It also happens when I slow down to make a right turn and I try to accelerate out of the turn.  If I'm very gentle on the throttle, I can avoid the clunk.  But that just messes with the tranny shift adaptation.  It also happens when Im on the freeway at over 50 MPH.  I will let of the gas and then quickly step on the gas.  It's like some kind of driveline lash.  Again. Don't know if its the transfer case or front diff.  The car is drivable but its getting annoying.  

 

I have reset the tranny adaptation with no luck.  I get the occasional 4-3, 3-2 downshift clunks(indicative of a valve body repair) after the reset, but the tranny behaves normally every other time.

 

So.  I need to find the location of the PSM relay.  I want to disable the PSM and remove the front cardan shaft.  That way I can find out if its my tranny/transfer case or the front diff.

 

Anyone else run into this problem?  Can someone direct me to where the PSM relay is located?  

 

Much Appreciated

 

Jose

San Diego, CA

Edited by Clutch-n-Throttle
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7 minutes ago, Clutch-n-Throttle said:

I need some help with my 06 CS(145k miles).

 

I am having a clunk in my driveline and Im trying to isolate the issue.  The clunk happens under a specific condition when I am slowing down from over 40 MPH.  For example, I begin to slow down for a red light ahead.  I let off the gas and brake slightly.  I slow down to say 15-25 MPH.  The light will turn green and I give it some gas.  Then I get a clunk in the driveline.  It sounds like its coming from the front axle or the tranny/transfer case.  It also happens when I slow down to make a right turn and I try to accelerate out of the turn.  If I'm very gentle on the throttle, I can avoid the clunk.  But that just messes with the tranny shift adaptation.  It also happens when Im on the freeway at over 50 MPH.  I will let of the gas and then quickly step on the gas.  It's like some kind of driveline lash.  Again. Don't know if its the transfer case or front diff.  The car is drivable but its getting annoying.  

 

I have reset the tranny adaptation with no luck.  I get the occasional 4-3, 3-2 downshift clunks(indicative of a valve body repair) after the reset, but the tranny behaves normally every other time.

 

So.  I need to find the location of the PSM relay.  I want to disable the PSM and remove the front cardan shaft.  That way I can find out if its my tranny/transfer case or the front diff.

 

Anyone else run into this problem?  Can someone direct me to where the PSM relay is located?  

 

Much Appreciated

 

Jose

San Diego, CA

First thing to visually check from underneath is the three mounts for the transmission, if they are cracked or split you get clunk when getting on throttle. 

Next is to check the engine mounts. Normally engine mounts will produce a vibration coming to a stop as the idle speed range is reached and driveline almost stops turning. 

 

So for me transmission mounts, mine were all spilt and yes I had a slight clunk if I was how shall we say "gettin on it" engine and driveline was dropped out for head gasket so was a no brainer.

 

Don't rule out out worn diff gears and driveshaft and even suspension bushes but this is less likely. 

 

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1 hour ago, lewisweller said:

First thing to visually check from underneath is the three mounts for the transmission, if they are cracked or split you get clunk when getting on throttle. 

Next is to check the engine mounts. Normally engine mounts will produce a vibration coming to a stop as the idle speed range is reached and driveline almost stops turning. 

 

So for me transmission mounts, mine were all spilt and yes I had a slight clunk if I was how shall we say "gettin on it" engine and driveline was dropped out for head gasket so was a no brainer.

 

Don't rule out out worn diff gears and driveshaft and even suspension bushes but this is less likely. 

 

Thanks for the quick reply. 

 

I was also thinking about changing out the transmission mount. I already changed out the engine mounts and strut arm about 2 years ago. 

 

But 3 transmission mounts?  I have been under the truck and I only see the main mount on the crossmember.  Where are the other two?  Most European parts suppliers only offer the main transmission mount that needs to be pressed out of the crossmember. 

 

Thanks again

Jose

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7 hours ago, Clutch-n-Throttle said:

Thanks for the quick reply. 

 

I was also thinking about changing out the transmission mount. I already changed out the engine mounts and strut arm about 2 years ago. 

 

But 3 transmission mounts?  I have been under the truck and I only see the main mount on the crossmember.  Where are the other two?  Most European parts suppliers only offer the main transmission mount that needs to be pressed out of the crossmember. 

 

Thanks again

Jose

Item 13 is the mounts we are looking at. 3 nos in total left right and rear. IMG_20161101_071022.png

 

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On 1 November 2016 at 9:29 AM, Clutch-n-Throttle said:

I got it now.  Those mounts are for the front axle and differential. I need to check those. 

 

Thanks again

 

Sorry mislead you with saying transmission mount lol. 

Did you find anything yet? 

 

I got a bit of a steering wheel shake when I accelerate a bit hard and higher speeds. I don't know if wheel balance, engine mounts, or just old bushes in the lower arm, ball joint and or steering tie rods and rack mounts are showing their age now. Nothing oblivious is loose or broke. I changed the right side top arm some weeks ago, the ball joint was oval shape and loads of play, I have the left side arm ready to fit but I checked and it's solid still so wasn't rushed to change it. I think given its 10yr old I might as well crack on and strip the left side replace that top arm and have a good search and check for anything else worn out. 

Wheel balance and rotation doing on Friday, alignment done 4 weeks back and all good. 

 

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I got under the truck yesterday.  I checked those diff bushings.  They looked like they had some small cracks in the rubber.  I tried moving the diff by hand and it felt fairly tight.

 

I checked the transmission mount that is attached to the cross member.  I can easily move the tranny around with my hand.  Going to replace that soon.

 

I hear you on the 10 year old truck.  Im at the point where I have to decide if Im going to spend the money maintaining it or get myself a newer Cayenne.  I love this SUV.

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14 minutes ago, Clutch-n-Throttle said:

I got under the truck yesterday.  I checked those diff bushings.  They looked like they had some small cracks in the rubber.  I tried moving the diff by hand and it felt fairly tight.

 

I checked the transmission mount that is attached to the cross member.  I can easily move the tranny around with my hand.  Going to replace that soon.

 

I hear you on the 10 year old truck.  Im at the point where I have to decide if Im going to spend the money maintaining it or get myself a newer Cayenne.  I love this SUV.

I'm at the point where if I sell this thing someone gets a bargain with a shed load of new parts and tlc for free and probably a great suv for a good few years more. 

That's why I made the decision now what ever happens I will persevere because I can never get back what I spent so have to take the enjoy instead. After driving the old man's ford Explora 2016 around with its pants 300bhp bag of nails sounding weak asthamtic engine I think screw spending 175k AED on that pos I'd rather spend 45k AED on a ctt with 500bhp and do some work and spend some money making it a great motor once again. 

 

IMG_20161101_101100.jpg

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