Hi. I'm a new member, and I'm happy to join this forum. I have a 2002-3 x-type Jaguar 2.5 petrol engine w. automatic transmission. It was built in 2002 and sold in the US in 2003. I'm dealing with a Can communication error code P1638. When I turn the key the instrument panel lights won't come on and there is no crank and no start. I need help in this matter. Thanks in advance.

 

Welcome. My first suggestion would be to go here: JagRepair.com - Jaguar Repair Information Resource and get the correct workshop manual for your particular VIN. Or look at the "sticky" posts at the very top of this forum and download the Jag Tech Info System, JTIS. There are manuals for 2002, 2002.25, and 2003 so I don't know where you fall in that range. Then search for your code. For example see the troubleshooting below. This is for a 2005 model year so may not be what you need exactly, best to make sure you are working from the correct manual.

I had a can-bus failure on a different car and in that case the advice I got was to disconnect modules 1 by 1 and see if the problem went away. I disconnected the ABS (car on but not running), still had the error. Turn car off, reconnect ABS, disconnect the module that controls door locks and power windows, still had the error. Reconnect that module and disconnect the headlight leveling module, no more can-bus error so I knew where the problem was.

 

Thanks a lot for the reply. I have been very busy these days, but managed to do the Pinpoint D Test, and the result was that I have a short to battery (pins 6 and 16 on the OBDII diagnostics connector). Where can the short be? and how should I proceed to get to that point?

 

Pin 16 should be battery voltage, on all the time. If you don't measure battery voltage there you have a problem between the OBD connector and the fuse box at fuse 25 (again this is from my manual for a model year 2005 so might not be the same wiring as your car). If you measure battery voltage there you need to concentrate on the wire from pin 6 which is the actual CAN bus data line. Because it is a network it connects to a lot of other modules. I would do that pinpoint test again with and without the transmission control module plugged in, for example. Then again with the climate control module unplugged. ABS module. Headlamp leveling module. Etc. If one of those modules is bad you will measure a different resistance and can focus on that module and the wiring to that module.

The CAN bus may also have a different resistance to power (meaning pin 16) depending on whether the key is in off, on, or accessory position. I don't know if the manual states the position of the key for these tests but it should.