Brake lights stuck on - help please
 

Hi, I hope I can get some help with 52 Connie CDT, I've looked at previous posts and tried suggestions but to no avail. The problem is a common one, my brakes lights won't go off, inc the HL one The problem originally started a year a go and was intermittent. I originally thought it was the ratchet mechanism slipping so I removed the dash by the pedal s and periodically reach under and push it forward with which seemed to work.

In January I decided to buy a new switch from a Landrover specialists which had the same part no as Rimmer Bros and fitted it to find that the switch didn't work (or at least that's what I thought) I refitted the original part and everything went back to before. After some to and fro I got a replacement switch, fitted it again to find that this didn't work however this time neither does the original part.

This is what I've done so far, I've checked fuses 7 and 13 , they are OK BLs still on, I've unplugged the switch totally, BLs still on , I've removed the LSM which does turn off the lights as expected but on refitting it the BLs are still on. Any suggestions?I'm thinking maybe the wiring is at fault between the loom and the connector, so contemplating removing the pedal box and checking this, but I'm still perplexed by the point that the lights stay on even with the switch disconnected!!! I read a post to say that usually they should go out? Also the lights stay on with the fuse removed? Surely that the power source for the switch?

Possibly a t4 session would help ?
Regards
Chris

2002 diesel
 

Hi Simon,

The brake lights circuit is not straightforward. For a start, the brake pedal switch is an electronic Hall effect device whose output actually holds the brake lamps off. So from your described symptoms, the fault doesn't lie with the pedal switch, unless it's maladjusted.
Which passenger compartment fuse box do you have? The relevant fuse may be different if you have the early design which has three neat rows of fuses whereas they're staggered in the later type.

You can check the power supply to the brake light switch with a multimeter:

Pin 1: light green/purple = +12v (auxiliary position on ign. sw.).
Pin 2: black = earth
Pin 3: purple/green = connection to ECM (this appears to be for cruise control disengagement)
Pin 4: green/purple = connection to LSM (which controls the lamps).

Simon

Hi SD1too not sure how I check the version of fuseboard it's a preface lift version , with 3 rows of fuses which run to 40'something , I've tried removing fuses 5 and 8 too which were labeled but still the lights remain on.

I've not had an opportunity to test continuity with my multimeter yet , was gonna check from the switch connector to the fuse, earth and LSM not sure how I test the feed to the ECU unless I unplug the ECU and locate the wire .

Is this strand of loom a harness that separates from the loom? Do you think it might be a earth problem?

Thanks

It won't be a fuse, but those you have mentioned supply the BCU in the pre-facelift fusebox and that is not part of the brake lights circuit.
Yes, please do (see my last post for details). I would refit your original switch and make sure that it is properly adjusted according to MGR's instructions.

Simon

Sounds like it's possibly the LSM that's faulty ;)

Had one last week that was doing the same, fitted and configured a replacement to the car problem solved ;)

If you have access to a spare you could try it and see if that does the trick ;)

Russ

Does the LSM have to be paired to the ECU by a T4?

Used ones can only be reconfigured using specialised software then T4 ;)

Brian, Phil or myself can definitely do it but there may be one or two others ;)

Russ

I've finally got around to testing the connection from the switch plug today, I modified a spare switch by exposing the rear of the pins and soldering and the insulating 4 extra wires to it. After checking the continuity on the switch I then plugged it on and tested the following:

1. Pin 4 to pin 25 on the LSM plug. All good
2. Pin 1 to pin 27 on the LSM plug (battery disconnected) all good
3. Pin 2 to the negative connection on the battery, all good
I didn't test pin 3 to the ECU

So remembering the lights are stuck on, could the fault lay with the LSM itself, as Big Russ mentioned? Is there anyway I can test that electrically with a multimeter?