LSM wiring diagram

[bigblue75]

Would any kind soul be able to provide a wiring diagram showing pin layout, wire colour and function please? Feel like I'm looking for something in a haystack but don't know what it is...

The LSM is for a 51 plate diesel with front and rear fog lights, Have a problem with brake lights sticking on.

Many thanks in advance.

[T-Cut]

Have you checked the brake switch on the gearbox? I don't think the LSM is involved with the brake lights is it?

TC

EDIT: I said brake lights but was thinking reverse lights! I'll wake up soon.

[bigblue75]

Should have mentioned it's a manual (2.0 CDTi), been working odd shifts and trying to eliminate possible faults as and when I have time.

[raykay]

Could be a problem with the pedal switch position, which is not a simple on/off switch!!

The bracket has a sensor that detects the pedal position, when the brake pedal is at rest, it is detected and the sensor allows a power feed to the LSM. When the pedal is moved away from the sensor, it breaks the circuit which is detected by the LSM which switches on the brake lights.

[BigRuss]

Have you tried a replacement LSM to see if that's causing the problem.
I've had one or two that have failed and caused the brake lights to stay on ;)
If you could possibly borrow one to try it would be useful in fault finding the issue ;)

Russ

[bigblue75]

Been searching through the forum and realise that swapping the LSM would eliminate that if the fault persisted.

Thanks for the advice, think a visit to Cossie Dunc will be arranged to test that and then begin the wiring fault finding if it not the LSM...

[klarzy]

any lamp warnings?

[COLVERT]

Could be a problem with the pedal switch position, which is not a simple on/off switch!!

The bracket has a sensor that detects the pedal position, when the brake pedal is at rest, it is detected and the sensor allows a power feed to the LSM. When the pedal is moved away from the sensor, it breaks the circuit which is detected by the LSM which switches on the brake lights.

What HE said.----:D:D:D

[bigblue75]

Not able to refer you to the original post regarding the problem,

have changed brake switch to rectify brake lights sticking on intermittently.. now brake lights work as they should when
i) ignition position 1
or
ii) all ignition positions when abs fuse (32 in passenger fuse board) removed.

otherwise they are permanently on (except when ignition position 0)

The problem is not currently a common one, not sure if that will change as cars get older.

Will contact Cossie Dunc to see about trying a known working LSM and take it from there.

[chgperformance]

Let me know how you get on, really want to fix mine! Fed up not having a speedo!

[Phil-T4]

I suppose you have checked Fuse 7 which supplies power to the switches?

[bigblue75]

Original thread
http://www.the75andztclub.co.uk/forum/showthread.php?t=253273

Checked all fuses for continuity, all good
checked all bulbs, all good
cleaned connectors at ABS module, LSM, break light switch, all rear lights

Switch working perfectly at ignition position 1 with ABS fuse (32) in place AND in all positions when ABS fuse (32) removed.

I think the switch ( LEMARK LBLS113 ) is working correctly,
I think something is causing the system to read the switch as being pressed when

The ABS fuse (32) is in place AND the ignition is at position 2 or 3.


Will try to get the car to Dunc as soon as possible, thought a diagram of the LSM connector might keep me busy til then.

[chgperformance]

Out of curiosity, measure the voltage on the pin at the LSM from the switch with the ignition on position 2 and the fuse in. I had around 7.3v which is too high. Indicating a short somewhere.

[bigblue75]

Did you check the voltage when in position 1?
Not had time to look at anything else, should be able to check this tomorrow.

Is this the green/purple wire fron pin 4 of the switch?

[bigblue75]

Had a chance to take some readings off the wire that goes from pin4 of the brake switch to the LSM (green/purple) using a fine pin through the wire, around 100mm from the connector block.

(pos3 is engine running), all values in volts, ground at base drivers side A pillar
Results were

Fuse 32 removed and pedal not pressed pos0 0.47 pos1 0.90 pos2 1.47 pos3 1.73
Fuse 32 removed and pedal pressed pos0 0.47 pos1 5.40 pos2 5.90 pos3 6.70

Fuse 32 present and pedal not pressed pos0 0.48 pos1 0.92 pos2 4.14 pos3 4.95
Fuse 32 present and pedal pressed pos0 0.48 pos1 5.36 pos2 8.30 pos3 9.75

The brake lights function correctly off the the brake pedal WHEN fuse 32 is removed OR on pos 0 and 1 when fuse 32 is present.

No continuity from pin4 to ground when fuse 32 was in or out.

Does this help make sense of the fault to anybody?