Brake lights stuck on - help please

Rennie71 · 3rd April 2016, 13:21

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?

Stickman · 3rd April 2016, 16:28

Possibly a t4 session would help ?
Regards
Chris

SD1too · 3rd April 2016, 17:07

Quote:

Originally Posted by Rennie71

... I'm still perplexed by the point that the lights stay on even with the switch disconnected!

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.

Quote:

Also the lights stay on with the fuse removed?

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

Heddy · 3rd April 2016, 17:14

Yep, this is a pain, mines intermittent and I have no solution, apart from replacing the switch. I'm forever looking in the mirror whilst braking at night to see if I'm getting a reflection from road signs on opposite side. I'm just lazy I guess, lost the reversing lights and sensors the other day, but they're working again now, will get a switch for a sunny day

Rennie71 · 5th April 2016, 18:32

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

SD1too · 5th April 2016, 19:21

Quote:

Originally Posted by Rennie71

... I've tried removing fuses 5 and 8 too which were labeled but still the lights remain on.

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.

Quote:

... was gonna check from the switch connector to the fuse, earth and LSM ...

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

BigRuss · 5th April 2016, 19:52

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

Rennie71 · 5th April 2016, 21:27

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

BigRuss · 5th April 2016, 22:55

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

Rennie71 · 17th April 2016, 15:59

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?

3rd April 2016, 13:21	#1
Rennie71 Newbie Rover 75 CDI Join Date: May 2015 Location: Pontypool Posts: 9 Thanks: 0 Thanked 2 Times in 1 Post	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? Last edited by Rennie71; 3rd April 2016 at 13:31..

5th April 2016, 19:52	#7
BigRuss Premium Trader 75 CDT Tourer,2.5 Launch Saloon, Omipro MG/Rover (T4) Join Date: Jul 2007 Location: Liversedge, West Yorkshire Posts: 5,405 Thanks: 1,105 Thanked 1,340 Times in 661 Posts	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 __________________ Replacement Key Service http://https://the75andztclub.co.uk/...d.php?t=244732 Full T4 Testbook diagnostics available. Diesel ECU repair and replacement. Options enabled or disabled as required. Diesel X-Power 135 and 160bhp, Rover 1.8T 150 to 160 MG 160 V6 to 177 upgrades available P.M. for details.

5th April 2016, 22:55	#9
BigRuss Premium Trader 75 CDT Tourer,2.5 Launch Saloon, Omipro MG/Rover (T4) Join Date: Jul 2007 Location: Liversedge, West Yorkshire Posts: 5,405 Thanks: 1,105 Thanked 1,340 Times in 661 Posts	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 __________________ Replacement Key Service http://https://the75andztclub.co.uk/...d.php?t=244732 Full T4 Testbook diagnostics available. Diesel ECU repair and replacement. Options enabled or disabled as required. Diesel X-Power 135 and 160bhp, Rover 1.8T 150 to 160 MG 160 V6 to 177 upgrades available P.M. for details.

3rd April 2016, 16:28	#2
Stickman Posted a thing or two Rover 75 saloon Join Date: Nov 2012 Location: Bordon Posts: 1,856 Thanks: 250 Thanked 403 Times in 352 Posts	Possibly a t4 session would help ? Regards Chris

3rd April 2016, 17:14	#4
Heddy This is my second home None Join Date: Feb 2013 Location: None Posts: 5,556 Thanks: 465 Thanked 1,161 Times in 924 Posts	Yep, this is a pain, mines intermittent and I have no solution, apart from replacing the switch. I'm forever looking in the mirror whilst braking at night to see if I'm getting a reflection from road signs on opposite side. I'm just lazy I guess, lost the reversing lights and sensors the other day, but they're working again now, will get a switch for a sunny day

5th April 2016, 18:32	#5
Rennie71 Newbie Rover 75 CDI Join Date: May 2015 Location: Pontypool Posts: 9 Thanks: 0 Thanked 2 Times in 1 Post	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

5th April 2016, 21:27	#8
Rennie71 Newbie Rover 75 CDI Join Date: May 2015 Location: Pontypool Posts: 9 Thanks: 0 Thanked 2 Times in 1 Post	Does the LSM have to be paired to the ECU by a T4?

17th April 2016, 15:59	#10
Rennie71 Newbie Rover 75 CDI Join Date: May 2015 Location: Pontypool Posts: 9 Thanks: 0 Thanked 2 Times in 1 Post	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?