Thread: D4 Reversing Lights

You can get CANBUS safe LED bulbs that will be much brighter (they have the required resistance included).

eBay has heaps and there are also more expensive but perhaps more certain-to-work options.

eg autobulbsdirect.co.uk: 382 Ultimate 92 LED Car Bulb - White or Amber Light
or hids4u.co.uk: 382 (P21W) LED Bulbs for Car and Vans, Can-BUS Compatible, Long Life

However, you will need to confirm your bulb type as they have changed over the years and the P21W I have linked may not suit.

Cheers,
Scott

It would appear that the CANBUS and ECU's do not monitor bulb resistance.

I have had a blown headlight globe, and there was no warning on the dash at all. But the car can tell me my washer fluid is low????

Anyway, I digress...

I have seen a D4 that has had all the external globes, excluding headlights, replaced with LED. They were much brighter, obviously, but no errors showed up, and the car behaved normally.

So, this is now on my list of things to do. Front indicators, park lights and reverse lights will all go to LED over time.

The only consideration is to make sure they actually fit into the available space. LED's generally tend to be longer, and as such, some may not fit behind the lens.

Originally Posted by Basil135

It would appear that the CANBUS and ECU's do not monitor bulb resistance.
I have had a blown headlight globe, and there was no warning on the dash at all. But the car can tell me my washer fluid is low????
I have seen a D4 that has had all the external globes, excluding headlights, replaced with LED. They were much brighter, obviously, but no errors showed up, and the car behaved normally.

Interesting, a blown headlight would be the main thing you'd be interested in having monitored I would have thought.
Makes you wonder because on the other hand there's reports like in this thread where replacement LEDs appeared to cause faults:
http://www.aulro.com/afvb/d3-d4-rrs/...blinker-2.html (refer posts by Glynhouse)

So thought I'd have a look in the D4 WSM and found this (emphasis is mine):

The lighting circuits are not all protected by conventional fuses as some are protected by MOSFET's.
The control circuitry within the CJB for each individual circuit can detect and isolate a problem circuit.
Failure of a lamp is not notified to the driver.
If a turn signal indicator fails the turn signal warning indicator in the instrument cluster will flash at double speed.

Operation of the lamps is performed using overload proof MOSFETs that can detect overload, load interruption with the lamps switched on and short circuit to positive with the lamps switched off.
An exception to this is the front and rear position lamps, front fog lamps and the reversing lamps which are supplied with power via relays within the CJB and are protected by conventional fuses.

Bulb failure monitoring is performed by the CJB processor.
The lamps are cold and warm monitored by the MOSFETs in order to detect bulb failure.
Relay controlled lamps have no diagnostic monitoring.

When the bulb or LED is functioning normally, the output signal voltage from the controlling MOSFET is 0V.
If a bulb or LED in the circuit fails, an open circuit occurs and the MOSFET outputs a signal of 5V to the processor.
The signal is interpreted as a bulb or LED failure and generates a Diagnostic Trouble Code (DTC) which can be retrieved using an approved Land Rover diagnostic system.

That description is not 100% clear as to what would actually trigger a fault visible to the driver over and above a DTC being stored but the "failure of a lamp is not notified to the driver" statement was a surprise to me.

Perhaps (wild guess) it is exclusively problems/changes to stop lights on D3s that lead to cascading faults (this was the case for Glynhouse in the linked thread).

Anyway, it's not too difficult to try out the LED bulbs and revert if any issues.
Now that I've done most of the internals I reckon the reversing ones are the next on the list.

Cheers,
Scott

Originally Posted by LRD414

hids4u.co.uk: 382 (P21W) LED Bulbs for Car and Vans, Can-BUS Compatible, Long Life

I have these on a 2010 D4... no errors and a useful increase in brightness.

D3's & D4's have slightly different programming.

From what I am reading above, the car can tell if there is a faulty LED, ie: brake lights etc, but not a conventional globe, as the power is supplied by a switched relay.

So, from that, it explains why a) there is no bulb monitoring, and b) LED's as replacements for incandescent's won't cause an issue.

Originally Posted by Basil135

So, from that, it explains why a) there is no bulb monitoring, and b) LED's as replacements for incandescent's won't cause an issue.

Good point but it does say that the headlamps are supplied by MOFSETs that are monitored. So in theory there should be a DTC for your blown headlamp bulb.

Scott

Originally Posted by LRD414

Good point but it does say that the headlamps are supplied by MOFSETs that are monitored. So in theory there should be a DTC for your blown headlamp bulb.

Scott

Yep, but I am wondering if that is referring to the Exeons and not the standards that I have.

Only reason I knew I had a blown headlight, is a mate was in front of me, and told me when we pulled up.

Originally Posted by Basil135

Yep, but I am wondering if that is referring to the Exeons and not the standards that I have.

Only reason I knew I had a blown headlight, is a mate was in front of me, and told me when we pulled up.

I thought that too when first reading the WSM but it makes specific reference to xenon monitoring being warm only, with cold monitoring switched off for xenons. So the way I read it is that halogen bulbs (assuming supplied by MOSFET) are warm & cold monitored.

This would suggest that you'd have a stored DTC but no warning on dash. Do you have a diagnostic tool, might show up?

Here's the WSM warm/cold section:

Warm monitoring is performed continuously when the lights are switched on by evaluating the diagnostic output of the MOSFET switches.
Cold monitoring is performed at 32 second intervals when the lights are switched off.
The MOSFETs briefly switch on the lights for approximately 1 millisecond (this is insufficient to illuminate the bulb or LED) and checks the bulb or LED as per warm monitoring.
Cold monitoring is not possible for the low/high beam headlamps of vehicles using xenon bulbs.
On these vehicles the cold monitoring of the low/high beam headlamps is switched off in the CJB.
The CJB detects a failed xenon bulb via a reduction in current flow to the affected headlamp's xenon control module.
When a xenon bulb fails, the control module's current consumption falls to 60mA, which the CJB detects as unsuccessful bulb illumination.

I wonder if this is another reason why changing from halogen to xenon is difficult, ie another part of the CCF related to this monitoring that requires editing.

Cheers,
Scott