My '99 VDP began throwing the yellow light and the codes above. No discernable performance problem, of course cruise is disabled when yellow light on. Code resets with engine off but reoccurs after operation (normal driving about 3-5 minutes).
Wonder where to begin and what might be the most common culprits. I originally posted this in the wrong forum, but I think this is where I belong.


Thanks in advance.

Larry

 

Larry,

I'm copying the following information you provided at the X350 forum to help the X308 experts to more fully understand the issues:

Cheers,

Don

 

Many times, P1642 is an artifact from connecting a scanner. Are you running a Torque scanner full time on the OBD port? In other words, does the yellow light come on even with no scanner connected? If so, then you have a genuine CAN bus error and you should try cleaning all of the CAN bus connectors. Check the archives for motorcarman's listing of the modules connected via CAN bus.

 

Yellow light came on independantly. Scanner was attached later to try and retrieve codes. Even now it's a soft code that disappears when the engine is off and the yellow light will not be on at the next startup until you have driven a few miles, then it lights again.

Thanks for the help

Larry

 

I want to thank everyone for their help so far, the knowlege on this site is tremendous. I hate to admit my ignorance but it seems like the problem is pointing to the CAN bus connections. I was directed towards the "archive" and especially those of "motorcarman" related to a systematic check of this system. My problem is I am having trouble navigating the site and locating archive information and info related to one individual. Would someone be so kind as to point me toward that info or a site tutorial whereby I might upgrade my navigation skills.

Thanks,

Larry

 

I don't think there is a tutorial, it was designed for factory mechanics and they have other proprietary programs to provide detailed information.
When I cleaned the CAN bus connections on my XK8 I copied the electrical diagrams from JTIS and traced the green and yellow wires used by the CAN bus through the various connectors and modules, which I then located in the car.
Before you start disconnecting anything, remove the neg. cable from the battery to prevent damage to the modules.

 

Larry, go to the top of this page. You will see a black horizontal bar with links. The fourth one from the right is "Search". Hit that little drop down arrow. Then scroll down and click on "Advanced Search". Then highlight the "X308 Forum" so you won't bother searching all the other forums. Then in the Keyword part key in "P1642 failsafe mode" and click on Search. It should come back with a bunch of previous posts on the subject.

 

Hi
motorcarman's listing of the modules connected via CAN bus is in the following thread (post# 6):

https://www.jaguarforums.com/forum/x...veryday-62726/

Jim Lombardi

 

As further information... The CAN bus is a network that interconnects those modules, much like "ethernet" connects computers. So, any one of those modules can act badly and cause problems on the network. The "possible causes" is specific that the fault means shorted CAN bus, so I mentioned checking the connectors, but any of the modules might be bad and cause a low impedednce to the bus, resulting in the same diagnosis by the ecu, I would guess.

 

Hi Larry
Here are 4 weblinks that will help you use the Jaguar Forums:

1st one is the USING Jaguarforums - USEFUL "HOW TO" quick link in the Jaguar Forums Advice / Feedback & Suggestion Center within the General Jaguar Forums section - look at post# 1 in the following thread:

https://www.jaguarforums.com/forum/j...2A%2A%2A-5912/

2nd one is How to Use the Search function supplied in the forum see post# 1 in the following thread :

https://www.jaguarforums.com/forum/j...acility-25219/

3rd one is how to use the internet search to find whenever you are looking for in the Jaguar Forums (use as a advanced search for finding information in the Jaguar Forums) see post# 1 in the following thread:

https://www.jaguarforums.com/forum/j...le-site-60209/

Last one is how to search using the Tag section of the forum search function (look at its post# 1):

https://www.jaguarforums.com/forum/j...18/tags-77874/

Jim Lombardi

 

Thanks to all, this should help me in all respects. Will take me a while to digest and use the info but I really appreciate all of the help. I have an OBDII scanner ( the "best" one Harbor Freight sells), downloaded the Torque Pro app for my tablet and ordered a Bluetooth connector, but I am curious about the groups thoughts on more sophisticated diagnostic tools and if there are any "collector\enthusiast" level instruments that have more functionality?

 

Yes- AutoEnginuity has a "Jaguar Extension" package that will let you read CAN drops at each connected module. I believe the total price (less the computer it runs on) is about $500.

 

Ross,

Do you know if JLR SDD can also read CAN drops at each module? Does that show up as a module-specific fault code or by some other form of communciation?

Thanks,

Don

 

What are CAN drops?

Regardless, SDD/IDS should be able to see each module. Any it can't see points to the fault. The Electrical Guide in JTIS shows the network so compare with what the diag tool (IDS/etc) finds.

It would also show any DTCs in each module so you could hope that only one other has CAN faults which would then point to the fault being somewhere on the wiring between it and the one you already have a fault on.

 

I assume Ross used the term "CAN drops" to indicate instances when communication via the Controller Area Network loses communication with one or more modules.

Using JLR SDD to diagnose our inoperative Adaptive Cruise Control, SDD can see the ACC module (green check mark to indicate it is connected and operative), but a fault code indicates an intermittent loss of CAN communication with that module at the ECM end (the code appears with a broken chain link that indicates an intermittent rather than continuous fault). I was curious to know if this scenario would fall into the category that Ross was referring to as a CAN drop.

My next diagnostic steps are to inspect the wiring harness from the ACC module back to the ECM and to remove the electrical connector from the ECM to check for corrosion, water ingress, etc. (I've already cleaned all of the engine compartment grounds)

Apologies for the slight hijack of Larry's thread!

Cheers,

Don