Hi All,

I'm brand new to this forum. I'm a bit of a car fan (several old Porsches, a BMW, a red Italian car from Maranello, a Toyota BJ-40 that I bought in Costa Rica, etc.), and I live in NJ.

I try to do most of the work on my cars myself, and I have a decent home shop with lifts, etc. Consequently, I sometimes get roped in to sorting out problems for friends. Such is the case with my current patient, a friend's beloved 2004 XJ8, bought new and now with 204,000 miles. Seems to be in great shape, but suffering from a major electrical issue.

It seems that almost every light is on on the dash (CIL,ABS,DSC,etc.). Clear them and they just come back. Tons of random codes (misfires, DSC Codes, etc.). Upon starting the car, the windshield wipers randomly begin to (slowly) move even with the wiper stalk in the off position. Turning on the wipers return them "home" causes the engine to immediately die! Similar random chaos during a road test.

Based on guidance from a few threads on this forum, I pulled the ECM to check for water damage (it was fine), cleaned it and all connections, then re-installed. No change. I then pulled the 40amp fuse #26 in the engine compartment fuse box (for the wipers and the "front electronics module"). Now, the car seems much better; the ABS and DSC deactivate over 15mph, but otherwise no lasting warning lights. Even though the wiper fuse is pulled, the wipers still creep 5" up the windscreen on startup. Manually resetting them to their resting position causes them to again travel part-way up the windscreen.

Help! New wiper stalk? New ABS module? New front electronics module (what does that thing even do?). How could wiper activation cause the car to die?

It's a very cool car - I'd appreciate any guidance from the experts on this forum who can help. Sorry in advance if there's another thread that addresses this issue.

Many thanks!!!

 

Are you able to post any of the codes?

 

I'm using a Autel MS409 scan tool. The Jag specific codes (read and then cleared):

P0171: System Too Lean Bank 1
P0174: System Too Lean Bank 4
P0300: Randon/Multiple Cylinder Misfire Detected
P0306: Cyliner 6 Misfire Detected
P0308: Cylinder 8 Misfire Detected
P1314: Misfire Catalyst Damage Fault Bank B
P1316: Misfire Excessive Emissions Fault
P0328: Knock Sensor 1 Circuit High Bank 1 or Single Sensor
P0442: Evaporative Emission System Leak Detected (small leak)

Lots of bad stuff on the surface, but I think these codes are symptoms and not the problem. That is, I was able to clear these codes and start the car - it runs smoothly and is firing correctly on all cylinders just fine (no MIL, no dash lights, etc.). But the windshield wiper motors are getting some kind of stray current or signal, causing the wipers to begin to move with the wiper stalk in the off position. When I activated the wiper stalk to return the wipers, the engine would immediately die.

I think the engine codes are the result of interrupted electrical signals (spark, etc.) that should be sent to the motor, but are suddenly interrupted as the car dies when the wipers are activated. As I said, not water damage or corrosion evident on the ECM module or board, so I then pulled the wiper motor fuse. That fuse supposedly also manages the front electronics module. Once I had done that and restarted the car, the car runs and drives perfectly fine.

Except... The ABS/DSC light come on the dash above 15mph, then turn off when the car drops back below 15mph. And, even with the wiper fuse removed, the wipers moved about 5 inches upon starting the car. To me, this means the wiper motor must be picking up some kind of stray current or signal from somewhere.

I'm wondering if a simple replacement of the wiper stalk is now in order? Regarding the ABS/DSC lights coming on, that would make sense if the front electronics module had anything to do with ABS or DSC. If not, I suppose a bad ABS module would throw both the ABS light and the DSC light (because DSC includes ABS, right?).

Sorry for the super long reply. Hope this makes my problem more clear. Again, really grateful for any suggestion or thoughts shared...

 

Before you do anything, check the grounds behind the headlights. They are notorious for deterioration and can lead to all the symptoms you mentioned.

 

Aha! Will do so this evening, etaent, and thanks very much for the heads-up!

 

When I saw the title contained "ABS/DSC/Wiper" my first thought is also the grounds behind the headlamps as I've had those same symptoms on both of my X350s. Your symptom of the wipers moving on their own virtually guarantees that. On RHD models it is typically the upper earth stud behind the RH headlamp (but it may be mirrored on LHD cars, so check both sides). That gorund point is the ground connection for your ABS module, the headlamps, wipers, and almost everything that is fed from the engine-bay fuse box.

The issue is that the studs corrode from the inside so you cannot see anything wrong without removing the bolt and checking the stud. Once the path to ground through the stud breaks completely, or goes high resistance, the next path is through the wiper motors which is why they move on their own (usually in short bursts as there is not enough current to drive them smoothly).

Be extremely careful removing the 13mm ground nuts because they sheer very, very easily. Once removed gently pull the harness terminals off and check for white oxidisation on the terminals and on the stud. I suspect you will find that the stud either breaks off when removing the nut, or is badly corroded with only a tiny bit still in contact with the car's frame. Check the resistance to another ground stud. If the stud is not in good condition then abandon it and use the headlamp retaining bolt nearby instead which has a good low resistance path to ground and is reachable without extending the harness.

On doing the nuts back up you want them to be hand tight only. DO NOT OVERTIGHTEN or you WILL sheer the stud off.

 

Also, how old is your battery? I would get it load tested. Anything under 12.6V your asking for electrical troubles...

 

I would agree that those codes aren't related to your issue, however if those codes come up again, come back and we can tackle that at another time.


As far as the ground connection as mentioned by Etaent and Xdave, definitely check the ground behind the headlights, the issue you are describing was sounding more like a bad ground, not so much a wiper stalk or module for that matter. Usually with the ABS, if its a module failure, you'll get a code, but on the 350's, ABS modules on these cars are pretty good, haven't seen too many issues with these, not like the predecessor X308 and X100 with the C1095.


Check the grounds behind the headlamps, and any other grounds you can see, and let us know what happens.

 

Xdave - so great of you to provide so much detailed advice and guidance! I'm back home in a few hours, and will do exactly as you suggest. I read the torque setting for the grounding stud nut was about 70-72in/lb, but it makes sense that even that much stress might sheer off the old stud. Worst case, I will follow your advice regarding an alternate point, or grind the surface clean and weld on a new Al stud... Will update progress tomorrow latest!

 

Abonano, good advice on the battery. It cranks really well, and I put it on a tender anyway once I got the car into my home shop. That said, I will check the date and replace if necessary. Thanks!

 

There was a post a while ago about the car dying when they turned on the wipers. He chased and chased things but did find the issue after checking many areas. I thought it was the stalk, but cant remember.
Found one
https://www.jaguarforums.com/forum/x...-141430/page3/

 

Battery and/or poor ground/earth as mentioned above should be your first line of attack.

If those don't solve it, I would think that points to some kind of wiring fault or short circuit and the wiper wiring should point you to the connectors and looms to look at.

Follow this link for the schematic:

http://www.jagrepair.com/images/Elec...al%20Guide.pdf

See if there is any shared connector with wiring from other functions that are acting up.

Good luck

 

Huge Progress!!! The problem was definitely the grounding points. I checked all three headlamp ground points and they were all badly corroded. The "top" ones on either side cleaned up nicely with a brass brush, and was able to confirm good ground for both with an ohm meter.

The third ground stud on the lower right broke off the body the instant I touched it (it's always the hardest to reach one that causes the problems). Anyway, I scraped some knuckles to clean the lower wires, then bolted them together with a jumper wire and grounded them to the upper post.

Moment of truth - turned on the car and everything works beautifully! Car drives smoothly and wipers work perfectly fine. So grateful for the great advice!

One remaining issue: as I'm drive the car the check engine light flashes. The light never remains solid, and on a 5 min test drive it occasionally stopped flashing. My code reader sees no codes stored or pending in the computer, and the car seems to function perfectly fine. Is this pssibly a "service engine soon" indication, or do you guys think I've got another issue to track down? I think my friend let her car sit for several months due to frustration with the (now solved!) electrical issue. Could the car have slightly contaminated gas causing an issue but not noticeably affecting performance or throwing a code?

Thanks again to everyone! I have no doubt this car is going to see another 100k+ miles f service thanks to your collective expertise and advice.

 

Well done. Same thing happened on my car. One of the ground points broke just touching it. Once the various modules can't establish a solid earth connection they'll throw up all kinds of confusing errors.



Do you mean the yellow fault light comes on and goes out or is there something specific in the message center?

 

Quick suggestion.

Disconnect the battery. First the negative cable, then the positive. After both cables are off the battery (did I mention that both are OFF the battery?) touch them together for 30 seconds. This is often referred to as a 'hard reset' and clears all the modules.

See if the check engine issue continues after this.

 

Thanks Mac Allen. It's not the solid yellow faul indication that flashes, but rather it's the engine shaped light in the tach that flashes. I will do the hard reset first thing in the AM and report back.

 

Success!!

I did the hard reset as per Mac Allan, but after another test drive it seemed clear the engine was still not running perfectly under load, and the computer finally indicated a misfire on cylinder 8. So, I replaced plugs and coil packs for cylinders #6 and #8 (both had initially indicated misfires). On start-up, I got a lot of smoke for a few seconds as cylinder 8 burned out built up oil (my guess), then the car settled into a nice smooth idle. So happy!

Just for the heck of it, I did another hard reset, then drove the car around on errands today. Handled fine and not a single CEL light or code. The car did briefly enter restricted mode once or twice, but immediately flipped back to full power and no codes or issues reported (is that normal following a hard reset?).

So... What can I say except THANK YOU to the 400+ people who viewed this thread hoping to help, and thanks especially to the 5 people who replied and offered their advice and guidance. I just gave the car back to my friend, and she and her whole family were a bit shocked that the car was repaired and running smoothly. I told them "the internet is your friend!", but not sure they really get it.

One last question; she needs to get the car inspected for emissions, but I think the car has to go through a "drive cycle" before all relevant sensors are in "ready" mode for emissions testing. I'll look through the forum as well, but just wondering if anyone has a quick answer on how many miles she should drive or any special procedures she should follow?

Thanks again!!!

 

They should not fail you for a not ready code, only a fault code in most states.

 

Thank you so much for posting this and for all the comprehensive responses. I have been having the same issue for a while now and have just got around to addressing it after the winter.

I read the post yesterday after I took the car out for a test drive, only to find that the wipers we're doing the slow climb and it seemed to be interfering with the ABS and the traction control. Turning the wipers on cut the engine, as was expected.

Anyway, I followed the advice from above and checked the ground wires behind the headlights. One has already been replaced, and you can see the old bold (pictured).The passenger side has sheared off, explaining the issues.

Here are the pictures for anyone suffering from the same issue.


Passenger side with the sheared bolt

Drivers side where the old bolt can be seen and the new ground bolt

If anyone has any thoughts on how to free the wires from the sheared bolt I would greatly appreciate the advice. I need to tackle this ASAP.

Cheers!

 

I'd spray it with electrical contact cleaner, as I did when I had the same problem recently. I too had that same bolt break when I tried to undo it. Then just try to prize the connectors down the remainder of the bolt which is stuck in the nut. They should come apart. My car would cut out when using the wipers and the wipers would creep. It also got lots of other fault codes being thrown. I've not had those major faults since. Recently had to replace the ground on your drivers side as I was getting random LH indicator failures. The clean worked for a while but replacing the ground has fixed it long term.