“If the relay module stops power to the light bulb what good is it just turning off the vcm?You still need power to the bulb?” …
Generally the problem that generates a flickering or intermittent warning on the VCM isn’t a burned out light bulb. Usually it’s a less then perfect connection between the bulb and it’s holder, but the light bulb is STILL WORKING ! Also the odds are excellent that a failed solder joint in the module won’t affect the operation of your lights but will probably trigger the warning, but it will be intermittent.
Don’t get me wrong if you hack the system you only disable the warning light not the modules. True if you have a legitimately burned out light bulb (that would be indicated by a steady, always on VCM warning) the system now can’t warn you … BUT … it eliminates all the false warnings that plague this system while not effecting the operation of the modules. So yes, once in a while you’ll have to walk around the car to verify all your lights are working, just the way you’ve done on every other car you’ve owned.
Over the years the intermittent false warnings drove me crazy, so I fixed it !!!
We seem to be going around in circles here - or maybe it’s just me that is confused!
What is/was the original problem with the lights? Are you confident that ALL the lights are working but you just have a rogue BFM warning or is one or more of the lights not illuminating when they should (which means that the BFM warning may be genuine)?
As you will realise, each BFM has a dual purpose. It acts as a switching device (via all of those relays) for individual lights and, in parallel, has a ‘fail logic’ circuit to detect a resistance discrepancy in each light circuit (open circuit or high resistance) which is probably what all those electronics are doing on the circuit board you photographed. They appear to be independent of the switching circuit relays, so if you are not getting power in to or out of. the BFM when one of those relays for a given light is manually depressed you need to look elsewhere than that burnt resistor in your photo.
Do you have the circuit diagrams for the lights/ BFMs?
If the problem is with the left rear tail/parking/side light, have you checked fuse 12 in the left fuse box AND that you have power out of that fuse (if good) to the left rear BFM on the Brown/light green wire?
The only bulb out is the left rear fog lamp, no power from module. Found a burnt (and I am talking charcoal) resistor, so when I get that fixed I will post the results. Found an electronic repair shop downtown so I don’t have to chase down 2 resistors.
Just logged in, Thanks for the info,.Just about to have another module installed.
Will attempt the next Failure!!!
No addressing a drive shaft vibration after rebuild… Even marked positions before removal.
Kindest Regards,
Have you checked the Jurid coupling? They can go hard and crack.other option is the centre bearing. Not sure what was done with the rebuild so sorry if these have already been addressed.
Got the pc board back, new resistors left and right, all is well out back! $50 for the repair. Now on to the one high beam lite and se if the dreaded bulb failure goes out!
David: I replaced u joints and center bearing. The issue i believe is the angle of drive line. Tomorrow i will purchase dial indicator from Harbor Frt. and use some front end shims under center bearing to address the correct angle.
Regards,
Grooveman: I must have clogged senses and unable to click,magnify or iconish(nice word) that enables a work around light module issue…
Do you have any suggestions? I must be three degrees this side of a primate, and just found the keyboard.
…
I shall try tomorrow…
Kindest Regards,
Well it seems both forward lamp modules are good. Swaapped left and right both work well on the left side but niether work on the right side! Checked the fuses and all are good. Is there a relay for the right side that I am overlooking?
I take it that you have checked for power at the BFM, if you have then check the earth point. Have you removed the cover and tried to manually operate the lights by closing the relays with your fingers?
Yeah well today I had a bulb fail light come on and I found the driver’s side tail light out.
I switched up a new bulb but that didn’t do it, so I checked that the bulb was in the socket correctly - however, as soon a I touched the bulb, it came on and the BFM warning on the dash went out.
So, put it all back together and started the car …BFM warning was on and tail light out (again! )
Took it apart and gave the bulb a little wiggle. Working. Took out bulb, cleaned socket, replaced - turned on lights …NOT working again!!!
Luckily had a spare receptacle from my parts car. Fitted that, all OK.
Decided to have a look what was causing the problem so removed the receptacle circuit board by melting the plastic tits with an old soldering gun. On the back of the circuit board, the running light and the backup light connections were seriously starved of solder.
The running light was only barely making a connection. Looking at that joint I wondered how it had even lasted THIS long!
Anyway, got my trusty portasol fired up and reflowed the joints then managed to re-melt the tits enough to reassemble the sucker. So I guess I have a new spare …
Good old BFM doing its job again! (Sorry Dennis ;-))
Very effective in detecting bad solder joints. A pity Jaguar didn’t use something similar during production instead of waiting until the darn thing fails in service!.
Hi Sorry for the delay, looks like I lost my way into the forum… Nun the less I replace u joints and rubber coupling… Brought angle into compliance, (2degrees).
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