Hello All
Having changed my bonnet actuator I've now got the same problem. A very friendly specialist checked my car this morning with their diagnostics to confirm its not my diagnostic device, but a problem with the car.

Car
XKR 4.2 X150 - 2007 UK

What is wrong?
I've had the nose off to swap the aircon condenser. I've changed coolant and oil. Since then the rh bonnet actuator has had low resistance. I've changed the actuator for a new one, no difference. I even fitted the new front bumper pedestrian sensors as they are known to fail, but no change. Not sure how I have a problem at the bonnet opening end when I went nowhere near that part of the car for the work I did.

What next?
I'm going to swap the actuator for the LH one just to see if the same issue with RH still shows up (just in case the new one is up the duff)

What I need please?
The specialist said these cars are notorious for wiring harness issues. Regardless I am going to have to trace through the loom to find the fault. Working on the assumption I can use a voltmeter for basics (like measuring battery voltage) I need someone to help me to understand how to use it to trace the problem - where should I do my measuring (I no doubt have a bad connection somewhere) and more importantly how?

I presume I use OHMS setting, with battery connected and ignition on? Put red pin in the plug I'm checking and black pin on earth point? Can I get an electric shock (obviously I won't be touching the 2000v headlights).
Electrics is not my thing, though I have ended up fixing a lot of electrical issues working on the knowledge of corrosion free connections to stop issues, and I've rewired many motorbikes and household things on my limited understanding but knowing how to make clean and secure connections

All help really appreciated- hoping I can find this to lose the misery I'm feeling about it! Luckily the car comes off the road soon for the whole winter, so I have plenty of time on my side as long as it is fixed before Le Mans next year! Hoping I can resolve this in the next week, because I know it will irritate me until I do.

Thank you

 

Update:
I good engineer I'm friends with (who actually works for JLR) has taken me through what I need to do, having given me a little theory lesson.
My resistance is low where the fault is.
He concluded - high resistance would be an issue with corrosion, bad connection etc; low resistance is unusual and sounds like a faulty component.

Natural conclusion is to swap the actuators to start with, and check, I'll probably do the same with the airbags just because they're apart anyway with the actuators out.
However after that I now know how to go through the loom with my voltmeter, so shouldn't need any advice after all

Thanks

 

Download a copy of the electrical layout - if you haven't already. Then you can see which circuits/wire to test.

 

Worn wires around front light cluster

 

My friend from JLR told me to exactly that, thanks for your help, verymuch appreciated

 

Thank you, I will take a look at that.

 

Hi George
Further thoughts about your comment. I did take the headlights out, so if this is a possible issue that could affect me getting a low resistance at the bonnet actuator then its an interesting concept, and i shall look in that area closely - it could make sense as that was the moment my problems began. However they are not on the same circuit.

i will swap actuators and do a diagnostic check.

 

I myself had a few problems around that area why I know , cooling fan , pedestrian sensors check around front passengers headlamp loom

 

That is helpful. Makes no sense if on a different circuit but certainly makes sense in terms of what happened to me, so I shall be going over it all thoroughly. Thank you. What was the fix in the end - as in what particular wire or connection was faulty?

 

Well I had to have them two front sensors replaced at an Indy and the cooling fan coming on by itself was traced to worn wires , sorry I never asked which one just paid them , but have seen others with similar problems you could check around the earth points in that area

 

Ive already fitted new front sensors, im going to start checking all the front end wiring. Swapping my actuators made no difference, so at least i know they're not faulty. Thanks

 

My problems are not the actuators- I've swapped everything around. Now my brake fluid warning is showing.
I think my battery is goosed...problems are coming up and the car hasn't moved an inch. Im buying a new battery just to be safe.

Note the kids managed to completely flatten the battery by connecting it and playing cds until everything went stone dead. I have recovered it etc but thinking on this is when i think my problems started. Im only just learning how vital full battery is on these cars

 

UPDATE - I cannot believe it but the problem is now fixed. I made the mistake of putting Vaseline in my electrical connectors - as we taught to do since year 0. Then applied dielectric grease to correct the Vaseline error.
So...went through every block connector I touched - hair dryer, then compressed air, contact cleaner, more compressed air. I died when I saw the same problem until the diagnostics showed only 1 error and a completely different reading. Spotted I hadn't reconnected the bonnet airbag and all my problems went away. Tonight I am going to get very very drunk before I put everything back together.

Learning from this - don't put anything on the block connectors to preserve them - maybe a light splash of WD40 only?

 

How do I mark this as RESOLVED?

 

Send a note to Graham or one of the other moderators and they'll do it for you. Thanks for closing out the thread!

 

Amen to that. While the questions regarding problems are important teaching tools, reporting the outcome and/or solution is also crucial. All too often we have an OP ask for help and then simply disappear without exercising common courtesy. And these days, we need all the courtesy we can muster.

 

Thank you Sean, someone has marked it RESOLVED so all good. Always like to let people know the outcome

 

Fully agree, nothing worse than not knowing the outcome, these posts can be so useful.