Hi everyone,

I'm glad to join this community of great car drivers, but unfortunately the occasion is not of joy. My car developed out of nowhere a turning on and off instrument panel problem, gauges going down and back up, all warning lights on / off, security red light next to gear shift blinks, power steering goes on / off, AC (climate control) will go on and off and later on show a communication error message. All this while driving for 20-30 mins and would stop if the car rest for some time in some cool place (problem comes faster if it's really hot outside).

Some details:

Model: Jaguar X-Type 2003, 2.5 Sport

DTC: P1638

What I did so far:

1.) New Battery - Varta 80ah

2.) Replaced all fuses related to alternator, instrument cluster

3.) Checked charge, after initial 15V when car starts it goes down to about 13.3v with head lights on.

4.) swapped R7 ECU relay with a similiar one.

5.) tried to play with the wires under the steering wheel but couldn't reproduce the problem.

6.) Cleaned and tightened all ground wires in engine bay.

7.) Added very thick power cables for +/- and all ground points in engine bay.

Please, before I go and send the cluster for diagnosis, provide me with some tips, maybe you have encountered the problem too?

Thanks in advance and greetings from Yerevan!

David

 

The DTC code says you have a network problem between the control modules. Maybe you could unplug/replug the ECU and instrument cluster. Do you have an automatic transmission? Sometimes water gets into the TCM (transmission control module). A dealer may be able to read something.

 

ArmXT, first off, welcome to the Forums. Lots of good information and people here. So, sit back, enjoy, learn what you can. But, please stop by the New Member Section and introduce yourself. We pride ourselves in being a better car group and as you will find, we like to get to know one another.

As for your problem, are all the lights going out on you along with the gauges falling to their OFF state? If so, you may simply have a broken solder joint on the backside of the instrument cluster which is causing the power to the instrument cluster to be interupted. Something you might want to try is starting the car and then giving the dash a good thump with your hand to see if you can cause the instrument cluster to fail. If you can make it do that, then this is pretty much confirming you have a bad solder joint. If only some of the instrument cluster is acting funny, then you are most likely looking at a communications issue and that can be interesting to figure out due to the networking inside the car.

As for the fix for a broken solder joint, you can remove the instrument cluster and look at the solder joints to see if you spot any with a black ring in the solder joint. The blackness is the crack. A little bit of time with a soldering iron may be all that you need to get your instrument cluster back to 100%. Just make sure not to be overly zelous with the solder as you can also create tons of problems if you get things shorted together. Otherwise, you may want to consider finding an electronics shop that will do the soldering for you.

 

Thank you for the assistance guys.

I have tried to re-connect the instrument cluster two plugs but nothing changed, will try to do so for the ECU. Is it in my foot-well btw? The one in the engine bay I think is the TCU. It's automatic, indeed.


I also tried hitting it from the top of the dashboard or from the sides, didn't bring the problem back, just after some driving of 30 min approx it will appear.

 

couldn't find a message edit feature and missed to mention that all warning lights come up and go, the background dim light is ok, just the functionality of the instrument (all gauges, odometer, etc) dies and revives infinitely.

 

Arm, the ECU is under the cowl on the right side of the car (ie, if you open the hood/bonnet of your car, it will be in the far left corner of the engine bay if you are standing at the front bumper). The TCM is under the dash of the car.

I wish you luck in trying to figure out where the source of the problem is.

 

You are right, that's indeed the ECU in the engine bay. Should I re-connect it after cleaning with a contact spray? I'm in doubt the problem is there and tend to believe it's the instrument cluster.


Thanks for the support, hopefully will update you with positive news soon .

 

Cleaning that connection will not hurt anything. You never know what you may find.

 

Hi again,

I cleaned today the ECU connector but nothing changed unfortunately, still it's disco time after driving for a while.

Anything else I should try before ordering an instrument cluster?

I'm having a hard time finding same serial numbered cluster on Ebay. Can I use something that has a different end letters to it? mine is 1X4F-10849-AL and the rest which are available come with BL / EL, etc. Any issues fitting one of those? I would take it to a Jag pro for re-programming anyway.

 

The ending numbers do mean something. The ending letters indicate a revision. A lot of the revisions are interchangeable. I do not know which are compatible and which are not.

 

Yes, they actually indicate different year / engine combo as far as I can tell. For example HD means that it's for diesel models. I wish I could know which are interchangeable, I see lot's of revisions with same characteristics as mine, yet can't tell which one to order...

 

ArmXT- I'm having the same issue. I replaced the battery 2 months ago when I initially had the code (and a no-start problem) and it has been fine until now. Now when my wife drives the car the dash lights up and the odo goes blank and once restarted it's ok but stores the P1638 code. Car drives fine but there is obviously an issue. What did you do to resolve the problem?

 

Replacing the instrument cluster solved the problem for good. Just make sure to get an exactly same one and re-program it with a Jag tech.

Good luck!

 

Thanks ArmXT. The more I read this thread and others on the subject I think I may have a slightly different problem. My wife has been the only one in the car when the fault occurs and she said all the warning lights would flash, the odo would blink, and the ACC panel acted up. She also said it occured when hitting a bump in the road one time. After it occurs everything goes back to normal with the exception of the CEL. No other drivability issues. It happens every couple days. Maybe a loose ground?

 

That's what it sounds like . Check your grounds inside the car and in the engine bay. jagrepair.com has the ground points list for you.


Good Luck,
The DR!

 

Hi,
I believe the ground point for the instrument cluster is located on the vertical stack that supports the radio and heater controls and is a known issue for this symptom.
Hope this helps

Gary

 

Turns out the culprit was the negative battery cable. I replaced it with one from NAPA for $12 and all is well. Thermo told me to do this a couple months ago when I was having no-start problems but I replaced the battery which solved it temporarily but I should have listened...

 

gbs, never question the monkey. He knows all, well, ok, most of the time he knows all. LMAO. By the way, my full name is Thermomonkey if you didn't know.

 

Spoke too soon. CEL back on after 4 days. I'm going to check the ground mentioned by gazza836 next. My daughters car is a 2002 Saab convertible so CEL's are nothing new at my house!


Greg

 

In case this helps someone, I had the same exact issue. It turned out to be two of my coils were shorting out or 'backfiring' as the mechanic put it which was putting a ton of voltage through the computer. It actually fried my transmission computer and I am now stuck with an endlessly blinking transmission light.