I would greatly appreciate some feedback/guidance on a problem that has been getting worse with my XJR, 117K miles.

A year ago I would get a "fearbox fault" notice maybe once every two to three weeks, it would go into limp mode, and with a couple restarts, it would work fine for a couple more weeks. The problem is now every day or two. HOWEVER, once I restart it and the car is warmed up, it will not repeat the rest of that day. The next morning, back to the same sad situation.

Recently the check engine light came on, I pulled the P0705 (P0705 Transmission Range Sensor Circuit malfunction) code out of the OBD. So I started the car, and gently started moving the shifter towards Reverse. It engaged reverse before it went in the shifter position for reverse, by perhaps 1/2". The backup lights did not come on until it was in the proper position.

Six months ago I put in a new stereo, and that involved moving the shifter out of the way and into Drive, and the entire assembly felt a bit... soft. I noticed no immediate chang after reassembly, and this has been gradually been getting worse anyway, so I do not know if this is related. I have searched this forum and others did appear to affect the adjustment of the switch doing the same thing.

I previously pulled the trans pan, there was no metal, the fluid was good, and the darn thing drives and shifts like a dream once I get through this very irritating routine I have to go through every morning now.

The thing that gets me is the no repeat once the car is warm. However, this morning I went out to the garage, started it, let it sit for 20 minutes, and got the damn fault anyway.

I backed it into the garage tonight, so I can put it in drive in the morning, and see if I get the same symptoms.

I am thinking of adjusting the switch position (yet to look into that procedure), but before I do that I am asking the forum for help! Has anyone experienced this before? Any advice would be most welcome.

Thanks from Norther California, home to the 49ers!

 

Have no experience with this code, so not sure if a mechanical change as you suggest would solve it, as the description seems more electronicaly. Would double check the cabling/connectors (also in the engine bay where the TCM sits), and then maybe try a new (2nd hand) gear selector unit?

 

Update: As my last post said, I backed it in the garage last night to avoid using Reverse. This morning I put it directly in Drive, and it had absolutely no problems. When I did put it in reverse when I got to my destination, again, everything fine.

 

Please keep in mind that check engine light for this particular code will only popup with a 2nd drive cycle, so when it lights up there was already an earlier occurrence during a previous trip.

 

Make sure its not the battery... I had intermittent gearbox faults due to bad cell in battery (tested fine with volt meter but any kind of load would dip the voltage enough to go into fault + limp mode). Pop the cover on the battery and make sure water levels are ok.

 

Have you checked to make sure the transmission electrical connecting is not leaking -- the fluid can actually wick through the harness and into the ECU in the bulkhead without ever leaking any fluid.

This can obviously cause all kinds of problems -- Get the OE MB part if you do see a problem as the after-market ones have not held up.

Are you sure the fluid is correct and at the proper level?

 

Megawatt, I had seen that comment on the forum several times, and I had the same issue with my Lincoln Mk VIIIs, so I had the battery load checked, no issues there. I was disappointed, as a new battery is a simple fix.

Yeldogt, I have not done that, but what a weird problem to have fluid wick that far up a harness. I will get down there and check that, but not sure how. And if I should need a new part, I would think you referring to a connector at the transmission, right? This part is replaceable without dropping the tranny?

Thanks guys!

 

Yes ... I agree a very strange problem -- but very common and thankfully a very easy fix. Do a search for w210 transmission electrical connector.

The MB part can be purchased for 30 bucks or so - I believe it is cheaper at the chrysler dealers.

 

As I had the P0705 code, it seems the j-gate adjustment I have read may be in order.

I am trying to get the JTIS to run on my computer, but it is Win7. Is there a procedure for this available anywhere here?

Thanks to everyone for their help!

Mike

 

Got the shop manual installed and working, see the procedure for the tranny selector switch. Seems simple enough, so I will hopefully get to it this coming weekend.

I got to the TCM module, examined the wires and found no trace of oil at the connectors. What further, if anything, is required to confirm this oil issue is not present? Do I need to look below too?

I have seen the mention of a hard reset to fix numerous ills. Seems a bit like snake oil, but hey, it seems to make a difference. Would you guys recommend I try this step first?

Any other ideas I should consider before diving into this beautiful XJR?

Thanks for your help.

 

It's like ripping off a bandaid when you are not sure the scab has dried

You already know that reverse engages without going all the way into the reverse detent position, and the code points directly at it ... so it's pretty much the first place you should start.

 

Got in the console and discovered someone had been there before me. Let some screws out, and other signs of sloppy work. The softness I explained was the Jgate not being fully screwed down. I checked out the linkage, and it seemed fine, so buttoned it back up properly and it feels tight and right. This procedure called for a battery disconnect, so did the reboot procedure as described. I also pulled and examined the TCM connectors, and all seemed well. Not a sign of oil. I wiped the connectors by inserting a few times in case of a bad connection.

Since all this done two days now and no faults, but I have to say the fix was a "maybe" until more time passes. It was happening daily, two days good is progress so call me optimistic.

I suspect the sloppy assembly of the jgate was the culprit, but with the reset and TCM pin swipe too, who knows? My console is now tight, they had left the two rear screws undone, and the shifter feels good now, so at least progress there. Time will tell with the tranny...

Thanks for all your help! And the Internet... how did we get by without it?

 

Real books and manuals ...

 

Yea, but you had to go buy them and they got all greasy... and we didn't have forums like this to help you through the rough spots.

Since the "fix", only one gearbox fault, and that was by my girlfriend. She was going back and forth trying to park it, and I have not been able to recreate it using it normally. I don't know if this is the only issue, but there seems to be a long enough trend to say I fixed SOMETHING.

She had the RPMs fairly high when the fault came on. Is this a normal fault for these vehicles... that is, if your RPMs are over 1200-1500 and put it in gear will a fit X308 give a gearbox fault?

Thanks!