ddsand, because you can control the throttlebody (when it acts up) via the buttons on the steering wheel, to me, that pretty much pin points the problem to the ECU. If you had a hard wire issue outside the ECU, pressing the buttons should have had no effect. The only thing that would have slowed the car down was the brake pedal.

Because of the lights that you are seeing on the dash (ie, cruise system engaging) and the throttle going wide open, this is pointing to a bad ECU. I can't think of or see anything else that would cause both of those symptoms other than the ECU.

 

Thank you Thermo,

ECU it is then. Am I better off trying to get them to update the software at the Jaguar Dealership or is it better to find one out of a 2005 xtype and replace it myself?

Thanks,

 

https://www.jaguarforums.com/forum/x...ptions-194959/

 

ddsand, unfortunately, replacing the ECU is something that has to be done by a shop unless you have an expensive computer with SDD software. I don't think reflashing the firmware of the ECU is going to do anything for you. Your problem seems to be a failing component, not a firmware issue.

 

Thanks Dell,

Any Validity in trying this first?

 

Thanks Thermo and Dell,

So my best case scenario is to find the same number ECU at a wrecking yard. Then take it with the car to a shop where they can reprogram my existing keys. it looks like Jaguar may be the only ones that can reprogram the ECU in my area but I will check some of the foreign shops.

Thanks everyone. I will let you know when all is said and done.

It may take a few weeks.

 

ddsand, I forgot your here in Utah. Give Import Auto Clinic in Layton a call. See if Kurt is in (owner, spending less time there as of late). He's a former Jag dealer specialist. I actually had my Jag just lately die (fuel pump) & they towed me to a high end only (BMW, Porsche, Mercedes, Bentley, etc.) shop. It was Friday late & Monday morning they called me and said take it to Kurt @ Import (like 1/2 block away). Which was where I wanted to take it initially and having gotten it running enough Sunday to limp home, talked to them Monday for thoughts on problem and cost. While I was there 4 people brought their Jags in, 3 others called, 1 pickup of his Jag. 1 Landrover & 3 other foreign cars. As posted elsewhere, I did the work myself, but was extremely impressed with the shop and the people. Current labor is $105/hr which is $25 less than Garff (SLC). Diagnosis is $89 first hour (for electronic, missing, etc. problems).

 

Great Dell,

Thank you for all your help.

David

 

OK, so a year later I think it is time to close the loop. I put up with the personality of this car and lived with the unpredictable cruise control for almost a year. One day when I got upset enough I looked up the parts on the cruise control and asked my local mech if maybe something else was wrong. (Dell, I did not ever go to your guy, but have him in the back of my mind.) I saw in a diagram there is a green switch on the brake pedal for the cruise control. I unhooked it and went to Advance Auto parts where they ordered me a new one for $7. I thought "great deal even if it doesn't work $7 for a part for my jag is cheap!!!" I disconnected the piece and drove home. No inadvertent Cruis Control on the way home. Non the next day on the way down. When I hooked up the new one the problem returned. I disconnected the piece and removed it permanently and wallah! no problems. No Cruise Control either, but no problems. Thanks everyone for your help. One day I will get back to it.

 

Odd that.. The relay is an "always on" while depressed (brake pedal normal) & "off" when pedal tapped or depressed. Sort of does point to a short somewhere in the cruise circuit. Just picked mine up today from Import for dropping my tank to replace the rubber hose that connects tank to fill spout that was leaking and causing an evap leak code(s) preventing emissions passing to re-license. $50 for part $850 total including labor, diagnostics, smoke leak test (initial and after fix).

 

Glad you have your's back. I was just looking over all the mods you have done. sounds like a fun car to drive. I still plan on taking my 05 in to have the wiring checked. Thermo also gave me some DIY help on checking for shorts. One other thing I did was replace the gas pedal throttle unit. I thought since it would set itself when I would hold it at a certain speed for a while there was something wrong there. No such luck. I don't think there are any other components other than the ECU so I have just left the green brake switch out. No cruise, oh well.

 

Clocksprings can be checked with multi tester w/o removing:
Remove airbag (torx T30(?)) to get access to top clockspring connector
find bottom connector and check resistance of each pin. If some pins have infinite resistance, replace clockspring.
I used to sell Jeep clocksprings on ebay and took some of them apart. There is roll of tape inside with electrical lines, tape breaks.
I had to test each clockspring before selling it.