When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The X300 ECU is not programed per say and is plug and play with a caviot
This is throttle position sensor closed value being matched or the ECU being oriented / adjusted with special equipment to the TPS so need the car there
There are mechanical factors involved if the present TPS gets to mechanical idle stop , return spring strength , cables lubed , throttle body internal throat clean of common build up guck , do not adjust or remove TPS yet , so an orientation before squaring up these would be putting the cart , money , time , and effort before the horse
Luck of the draw if a replacement ECU with it's factory done orientation will match the your original TPS in the closed area
You can put in the ECU and see the idle speed of 700 ish as that would be the area of concern , but.........................
The TSB ( noted by a R493 sticker on it or later years ECU manufacture suffex #s ) that Bob posted is related to California emissions putting in a upgraded EGR valve and running it ( maps ) to satisfy the regulators and may or may not affect your emissions sniff test passing , I think even the California models have a specific part # , emissions A , B , C , D ect on the Jaguar side
Water ingress comes from a seam in the sheet metal joint seam the under the plastic tray for the windshield wipers , the screws for the tray are plastic and can stick / snaped off so work some penetrating spray in somehow on the threads before hand , you can go back in with stainless steel screws
Your original ECU connectors both case and car side can be replaced as readily available TE Connectivity manufacture Econoseal series 3 / size 0.70 part # 344111 - X
The individual rubber seals on each wire can let water through , my seals were missing , corrosion can accrue as the wires are crimped on the sockets effecting the sensors return to ECU signals
Ensure the external ground strap is on the ECU case
Last edited by Parker 7; Feb 15, 2025 at 02:52 AM.
Thank you very much - that is the information I needed.and the dealerships have been no help at all. I do have a question on the PROMS on my '96 VDP. Should I swap them out from the old unit and put them in the replacement unit? Or should the ones from the replacement unit being same year and model work?
I wanted to mention I just got a 2013 supercharged XJ with only 15k miles on it. Lovely car - not a ding anywhere. Read everything I could find on it but just wondering if in this very knowledgeable group there is anything I should know or look out for. Any pearls of wisdom very much appreciated as is the save-me-from-pulling-out-what's- left of my hair information provided.
On the 96 if the TSB has been done and the upgraded EGR valve installed ...................if done by paperwork there will be a R493 sticker in the engine compartment and on your original ECU
In shifting the Jaguar ownership from Ford to India there is a gray area that a dealership has in having the equipment to maintaining with equipment test to certify you have resolution before rolling you out the door , reputation that they know what they're doing , Motorcarman can have his say certainly with his experience in a Jaguar Dealership
I ran into this myself on the 96 with Jaguar and a transmission issue with an independent shop of high caliber and I respected the mechanic's approach that his work output is garneted against a valid test equipment result
You can always use the new ECU and get the car started and then go to the new ECU squaring up if good idle and then if emissions test fail come back to the PROMS question ? I think the EPROMS upgrade only relate to the EGR and emissions satisfaction with the regulators concerns , This from my understanding was the reason the V - 12 was stopped in production in 96 as a regulatory issue
Word of wisdom , never install battery in backwards , positive post car fwd , mark with tape and a big marker arrow
Ask me how I know .............................................twice
You can always open a Words of Wisdom thread on each car area of the forum
Thank you Motorcarman. After a dozen or so more or less Jaguar "experts" - you finally put me on the right track. Installing the replacement ECM fixed almost everything. Oddly, the horn stopped working. Something to do with the other night when it was raining and although the ECM was out and the car was covered, the horn went off for several minutes, then stopped and then started again. I disconnected the negative battery terminal but now it doesn't work. I'll check fuses and relays and see
if that is the issue.
cheers
Again, much thanks. Between you and Motorcarman, the solution was found and the old gal is running like a champ. Guess it was luck that the ROMs were the right
ones and I didn't have to swap with the old unit. I know that a lot of guys have problems with this car but other than the ECM drowning, I've had virtually no problems
with my VDP for six years and 70k miles. Only issue now is the AC quit and my mechanic couldn't find a problem suggesting it might be the expansion valve. I''ll try replacing it and recharging the system unless you gents think there might be something else to look at. Compressor checked out and system properly charged at
AC place but no go. Anyway, again thanks for all the assistance, much appreciated.
best
Kragby
Motorcarman ( Bob ) has an easier suggestion before expansion valve replacement
There are a couple of other things to check that are easy , there is a simple cabin temp sensor to clean ( use no solvent to dry out bearing , just air and a brush )
And there is a whole system test with codes from the climate control panel that someone has made a video of , this test does not " see " everything
The car horn relay is the one attached and on the corner of the left engine bay fuse box , you can swap this relay with the one on the right engine bay fuse box , the right is needed to power the engine ECU so don't drive on a swapped relay least get stalled
2 fuses either # 10 , 12 , 14 , or 16 in same fuse box , the 2 other slots of these 4 positions will be empty
The relay is closed by a ground provided by the steering wheel center
Last edited by Parker 7; Feb 16, 2025 at 07:06 AM.
You are obviously a fountain of Jag wisdom and are ever so helpful - thank you for that. I do have a new puzzling ( to me anyway) problem.
After replacing the ECM tho not sure it is directly connected, the electric trunk latch, speedometer, and horn ceased working. I'm not
sure where to start or what if anything is common to these other than possibly a ground? Would you bless me with some jag wisdom?
thanks