E30 Zone

Hi Guys,
took my 320 out for a nice drive in the sunshine today..
On the way home i noticed a red warning light on the dash next to the handbrake light!!-Im thinking that it could be the brake pad warning light???Although the brake's seem fine!!

Can anyone confirm this??????
Mnay Thanks...

it's a worn pad sensor,mine are disconnected due to greenstuff pads.

maybe a wire has snapped.you get one on the fron pass side and one on the rear drivers side if discs all round iirc

or pads will feel fine but just getting low thats all,if wire not snappped/came off , mine came on last year and all was fine, but pads were worn needed changing

System works by embedding a wire into the sensor block,when the wire wears through it shorts to earth via the brake disc,thus putting the light on.

Therefore if the wire fouls on any other part on it's journey to the sensor,such as the wheel rim or the suspension,the light will come on.In addition to this,there is a control circuit within the instrument cluster that can play up,most likely here is a large resistor mounted on the main board behind the temp gauge.

Do the sensors need replacing once they trigger the dash light?

oomz1975 wrote:Do the sensors need replacing once they trigger the dash light?

Yes along with the brake pads

Daimlerman wrote:System works by embedding a wire into the sensor block,when the wire wears through it shorts to earth via the brake disc,thus putting the light on.

quick update.....
went to take the ns/f wheel off this morning to check for pad wear-i started to jack the car up and it slipped off the jack!!!!,damaging part of the tech 1 side skirt!!!!!!....i gonna take to the local garage tomorrow!!!!!just in case i damage it even more!!!!!!

all ways use a trolley jack on the lollipop bush bracket,i never use the boot jack if i can help it and then i have a wheel chock to use with it.

magpie wrote:all ways use a trolley jack on the lollipop bush bracket,i never use the boot jack if i can help it and then i have a wheel chock to use with it.

+1

They're for emergencies..

the same red warning light has come on my the dash. but the pad sensor is disconnected on my front pads. i have drum brakes on the back. do they have sensors on ?

snakebrain wrote:

magpie wrote:all ways use a trolley jack on the lollipop bush bracket,i never use the boot jack if i can help it and then i have a wheel chock to use with it.

+1

They're for emergencies..

I always carry a mini trolley jack

burtcocain wrote:quick update.....
went to take the ns/f wheel off this morning to check for pad wear-i started to jack the car up and it slipped off the jack!!!!,damaging part of the tech 1 side skirt!!!!!!....i gonna take to the local garage tomorrow!!!!!just in case i damage it even more!!!!!!

I really do worry about yourself and your abilities to run/maintain an elderly car.


If you cannot even lift it to safely to examine problems.......

daimlerman wrote:

burtcocain wrote:quick update.....
went to take the ns/f wheel off this morning to check for pad wear-i started to jack the car up and it slipped off the jack!!!!,damaging part of the tech 1 side skirt!!!!!!....i gonna take to the local garage tomorrow!!!!!just in case i damage it even more!!!!!!

I really do worry about yourself and your abilities to run/maintain an elderly car.


If you cannot even lift it to safely to examine problems.......

+1

That's nothing, i released the jack under my french diesel turd with the axle stand not fully removed, put a nice dent in the sill before i realised

far too much chemical abuse or daydreaming going on.
EVERYTHING about motorised transport is dangerous, and should be treated as such.
Burt stick to public transport and make the roads a safer place.

daimlerman wrote:System works by embedding a wire into the sensor block,when the wire wears through it shorts to earth via the brake disc,thus putting the light on.

Therefore if the wire fouls on any other part on it's journey to the sensor,such as the wheel rim or the suspension,the light will come on.In addition to this,there is a control circuit within the instrument cluster that can play up,most likely here is a large resistor mounted on the main board behind the temp gauge.

The pad wire does not short to earth via the brake disc or short to earth at all.

Both pad sensors are in a loop and when the loop is broken the sensor (inside the cluster) see the change in resistance and switches the bulb (on a separate circuit) on.

The pad circuit is similar to a Wheatstone bridge arrangement, and will turn the warning light on if the loop is broken, changes resistance by a significant amount OR shorts to earth.

It is such a shame that a certain zoner will only use his skill and expertise to critise others....

Brianmoooore wrote:The pad circuit is similar to a Wheatstone bridge arrangement, and will turn the warning light on if the loop is broken, changes resistance by a significant amount OR shorts to earth.

As im sure you know, the sensor on an E30 and any BMW for that matter works by breaking the loop and changes the resistance which is measures inside the cluster. As this is an E30 question then the correct answer is only relevant.

Besides, pad sensors that do short to earth, do not short via the brake disc!

daimlerman wrote:It is such a shame that a certain zoner will only use his skill and expertise to critise others....

Its such a shame that a certain zoner continues to post up drivel and mis inform others.....

The pad warning light on an E30 comes on initially when the wire loop in the pad sensor shorts to the disc. At this stage the light will flicker, until the wire is severed when it will remain on all the time the ignition is on.

I think the final answer to this is that if the light is on there is either a lose connection somewhere or the pad is worn out. I don't think it really matters where it shorts to at the end of the day.

Not really worth arguing over.

How do you work that out Brian?

Because I have the full circuit, fully understand how every aspect of it works, plus it ties in perfectly with my experiences of E30 pad warning lamps over the seventeen years I've been driving them.

Well you obviously can't understand how every aspect of it works so i suggest you take a closer look at the full circuit diagram to see where you are going wrong.

I can assure you I fully understand how every aspect of the circuit works! I may not know how off of the top of my head how many Zinnobar red 325i E30s were produced during the eleventh month of 1988, or any other 'nerd' type statistics, nor do I want to, but having been a fully qualified electronics engineer for more years than you've been alive, I do understand electronic circuits, especially a relatively simple one like the circuit in question.

I also thought the same warning light comes on when brake fluid is low?

I thought it was a break in the circuit thing.. No grounding involved.. That is how it worked on my e36 anyway. Can't remember about the e30.

Jesus325iTouring wrote:I also thought the same warning light comes on when brake fluid is low?

stick to the subject Jesus, oh sorry, just checked the o/p and you were

adit wrote:

Jesus325iTouring wrote:I also thought the same warning light comes on when brake fluid is low?

stick to the subject Jesus, oh sorry, just checked the o/p and you were

Thought there was a different warning light for that ?

Quick Q related to the OP - if the sensors are not present, or present but not actually clipped into the front pads will the light be on ?

The light will be on if sensor not present - I replaced rear pads, but didn't have a replacment sensor, result - light is on.

My light also flickered for a while before staying on permanently prior to the pad replacement.

Kemlo wrote:The light will be on if sensor not present - I replaced rear pads, but didn't have a replacment sensor, result - light is on.

My light also flickered for a while before staying on permanently prior to the pad replacement.

That was what I was hoping - on my turd There is no sensor on the back at all and the sensor on the front is there but not clipped into the pads - Its on the list

capri_rob wrote: on my turd There is no sensor on the back at all

On E30s with rear drum brakes, there is a short loop of wire connected to the plug of the fuel pump, etc. loom under the RH side of the rear seat cushion, which simulates the rear pad sensor.

bss325i wrote:

daimlerman wrote:It is such a shame that a certain zoner will only use his skill and expertise to critise others....

Its such a shame that a certain zoner continues to post up drivel and mis inform others.....

?