Brake Warning Light

[whatarehughlike]

Help please...

The brake warning light is on, on my Lotus Esprit SE and I've read that it's because of low brake pressure. From all the research I've done I understand that it's due to one of two things, the accumulator or the ABS pressure switch.

Prior to me attempting to fix it, the ABS motor ran every three times I used the brake pedal. I managed to source an accumulator and today replaced it. When I finished, the pump ran every six times however the brake warning light is still on.

Before I go and source an ABS pressure switch, is there anything else it could be?

Does anyone know where I can get a replacement switch from and how much it will be?

I've seen there is a company in Australia that makes replacements for $360. They're called Lotus Marques. Does anyone know if they're any good and does this sound like a reasonable price.

Thanks in advance

.....a now financially insolvent Lotus owner!!!!!

[sailorbob]

Use Espritmon and a suitable ALDL cable to find out what the ABS error code is.

[Bibs]

Are you sure your car has ABS?

[rizla603104]

Does the light specifically say ABS? Or is it the red light with the (!) on it?

[Vanya]

Sounds like it's the switch - I don't recall any other errors other than low accumulator pressure/busted switch low pressure side/ that would cause this

If you pump the brake pedal say 20 times and let the pump run upon ignition, and then release the handbrake without having touched the brake pedal, is the red brake warning light still on? Does it come on only after pressing the brake pedal once or twice?

I think you might have to go the whole hog and get the switch. Either original or a second hand part. There's currently the whole assembly (master cylinder + switch + accu) from a Sport 300 on eBay for £300. There's also one here in Sweden from a breaking S4 (whole assembly) for about the same price. The downside is one doesn't know whether these work properly at all!

The Australian switch has been thoroughly tested - there are threads in which it is discussed, so you don't need to worry about this. It has engineering approval from the Australian road/transport authority (don't recall which) - this was necessary as modifications to systems such as brakes need to be tested for conformity.

The downside it that there is no 3rd connector which displays the red brake warning light if the pressure is too low. Some have argued that this function is useless because one way or another, if you REALLY have low pressure, you will notice by the fact that its a lot harder to stop than with a correctly functioning system.

The choice is yours. But I'm in the same boat, and know of at least two others here in Stockholm who are. I'm gonna try and change my accumulator come spring and then on to the switch if that doesn't do the job. What does Espritmon say?

[dodge1979]

Take a read of my thread in this section on getting the delco brake system workin properly...and for a lot less than the system from Australia....its not a difficult fix to do if your competent...a lot of the views on this system are misguided and uninformed and panicky....the time I spent sorting mine out shows how it can be done and at a very reasonable price too....

Take a read of my thread in this section on getting the delco brake system workin properly...and for a lot less than the system from Australia....its not a difficult fix to do if your competent...a lot of the views on this system are misguided and uninformed and panicky....the time I spent sorting mine out shows how it can be done and at a very reasonable price too....

[whatarehughlike]

Right I've been playing around with it over the weekend to try and fix the problem. Firstly the warning light that comes on is the red '!'. The orange ABS light used to come on but I replaced all the sensors (including the £&@%^! rear offside one that broke off inside) and that problem was subsequently solved.

The red light comes on as soon as the ignition is turned on and never goes out whether the handbrake is on or not. I've checked the handbrake switch and there's no problem there.

I changed the accumulator and that did make a difference with the pump only going off every six times rather than every three.

I've tried hooking it up to espritmon but oddly it doesn't seem to show any error codes!?!?! I will confess that I am a bit of a Luddite when it comes to computers so I'm probably doing something wrong..... But I really am stumped. In any case I think the only option is the Australia option..... Although before forking out the money I'm just going to read the 'dodge1979' solution.

[Mike6]

Have you checked the simplist things first like a loose wire, dodgy connection or poor earth

[sailorbob]

If it is the brake tell tale then it is one of three things:

Hand brake on

Brake fluid low

Accumulator pressure below 1800 psi

If you are sure the handbrake switch is OK try unplugging the low brake fluid switch next.

[lotus4s]

I'm not positive but I seem to recall another reason for that light to come on and it was either a brake light out or a problem with the brake light switch. Are your tail lights working properly?

Edited November 20, 2012 by lotus4s

[sanj]

From the ABS manual:

This tell tale will glow red with the ignition switched on, under any of the following conditions:

i) When the parking brake Is applied;

ii) If the brake fluid level is low;

iii) If accumulator pressure is below 12,400 kPa (1,800 psi). If the brake pedal has been pressed

several times with the ignition off, stored hydraulic pressure may fall sufficiently to activate the tell

tale. The electric pump will start up when the ignition is switched on to restore pressure, and the

lamp should go out within 40 seconds.

As a bulb check function, this lamp should light when the ignition is first turned on, and go out when

the engine is cranked. Under normal circumstances, with the engine idling, the tell tale should light when

the parking brake is applied, and go out when released. If the lamp fails to go out when the parking brake

is released, or comes on whilst driving, stop immediately as the brake fluid level or accumulator pressure

may be dangerously low. Only non power assisted non-ABS braking on the front wheels may remain.

[lotus4s]

I hear what you're saying Sanj and I know what the manual says but I had a similar issue several years ago and it turned out to be something simple and not one of those 3 conditions but I just can't remember the details.... old age you know.

[sanj]

Could it have been a maladjusted parking brake switch?

[lotus4s]

Could've been...

[whatarehughlike]

Update!!!

Sorry for the delay but I've been busy at work and being that I'm a technophobe, it's taken me ages to work out how to use Espritmon.... but I have finally done it!

These are the things that I have done

1. Replaced the accumulator - This appears to have helped the braking system but not fixed the warning light.  The pump runs every four times rather than every other time I use the brake pedal.
2. Checked the handbrake switch – This works, there is no break in the circuit and every time I release the hand brake the warning light flickers slightly.
3. Checked for any signs of damage to any wiring.

Firstly in relation to Espritmon I connected it up and looked at the ABS screen.  Thankfully there was nothing suggesting low pressure or anything similar.  I did however see what appeared to be a fault with the '2 - tail or diode' (I would include a screen dump but I'm still trying to work out how to do it!!!!).  Does anyone know what this means? (I feel that this might hold the key to fixing the problem)

 

I have bought the brake manual and there it talks about various problem solving methods for various error codes.  I can't see any error codes on Espritmon.  Could someone tell me where they are so I know I'm looking in the right place. 

 

Is there anywhere on Espritmon that tells you what the brake pressure is, or do I have to hook it up to a pressure gauge to double check?

 

Having read through the manual at great length it appears that the only thing it could be now is the low-level fluid sensor – do they make these anymore and what’s the price?  (I’m guessing not bearing in mind it’s a part I need!!!!!)

 

Any other ideas or suggestions would be helpful

 

 

[sailorbob]

Have you tried unplugging the low level sensor?

[PaulEspritGT3]

It looks unlikely to be a pressure problem.

You may already know this but from the Service manual the full error code description is "CODE A0002: ABS TELL TALE SHORTED TO BATTERY OR BRAKE DIODE SHORTED", I have attached the relevant pages...

[whatarehughlike]

Derek - I've tried unplugging the low level sensor and that made no difference but thanks anyway

Paul - now you've pointed that out I'll give that a proper look tomorrow.

Thanks for the help

Here's hoping!!!!!!

[sailorbob]

After checking the hand brake switch (you did try disconnecting it?) and the brake fluid low level switch then the next switch to check is the accumulator pressure switch. Try disconnected that one next. BTW the ABS error code relates to the ABS tell tale not the brake tell tale.

[sanj]

It may be that the low level and/or parking brake switches are normally closed, in which case disconnecting them would emulate the fault condition. It wouldn't hurt to try shorting each in turn.

[sailorbob]

IIRC the handbrake and brake fluid low level switched are normally open and close to illuminate the switch. The accumulator pressure switch is closed unless the pressure drops below 1800 psi but the signal goes through the lamp driver module (which is basically a solid state relay) to invert it.

TBH, I suspect the handbrake switch since flickering was seen when the handbrake was applied and released.

Edited December 13, 2012 by sailorbob

[CHANGES]

There are three terminals on the handbrake micro switch. 

 If the switch is connected or adjusted wrong you will get

the symptoms you describe..

[Vanya]

There are three terminals on the handbrake micro switch. 

 If the switch is connected or adjusted wrong you will get

the symptoms you describe..

 

I used to have the flashing ABS lamp + fixed brake warning (!-light) prior to changing my accumulator - after changing it, the ABS issue is no more, however I still have the fixed parking light on. Fluid levels are a-ok (the reservoir is in fact slightly overfilled).

 

When I release the handbrake, the light dims EVER so slightly. This originally led me to believe that the lamp might be two lamps overlaid over each other and that the handbrake release works ok (disengages that lamp) - hence leading me back to possible low pressure.

 

Do you think the handbrake light might be worth a look after all? Otherwise I guess I'll go the whole hog and buy a pressure gauge and possibly the Australian pressure switch solution thereafter...

 

Regards,

Vanya

[dodge1979]

Could just be a wiring issue then..faulty earth or connection...id investigate that before other solutions

[OwenGT3]

I've been having major problems with my abs light coming on, but now I have the handbrake/fluid light now coming on as well. I have checked the micro switch on the handbrake, it seems to be all right, nice and free, I did wonder if it had got stuck on as I had have this happen before if the handbrake has been on for a while, which it had, but I don't think this is the problem.

 

I don't think it is the switch, but something to do with low accumulator pressure. I've got the switch from Steve in Aus now fitted to my car and working all right, also I have a new accumulator fitted. I have also been over to Gerald Turners at Newmarket, he helped find the fault codes on my car with the Tech 1.

 

I had a long old list of codes, but most were down to fault diagnosis, in the end after clearing the codes and starting a fresh it was recording just one code, low accumulator pressure, and as this is one cause in the manual that could put the red handbrake light on, I think it has something to do with the fault.

 

With a new switch and accumulator, pump working correctly, good solid pedal on last nights road test, in theory I shouldn't have any lights on, but I am still getting a problem with lights on that is really wearing me down now, the problem has gone on for months. I am visiting Gerald's again to see what codes are being recorded again, but I think it will be the same as before, low pressure. 

 

This shouldn't be a problems as I have to de-pressurize by pumping my pedal at least 40-60 times to have a solid pedal, also the pump now runs on the 6-7th press of the pedal, so it's holding pressure no problem. It's getting to the point where I'm considering ripping all the abs off and just leaving the master cylinder and booster, which are working fine now. I was going to upgrade the front discs with some of the 323 mm discs from PNM Engineering to help with stopping.

 

Having spent £500 on the system I don't really want to rip it all out and replace, so am happy to just have the master booster still fitted. I've examined every part in the abs system, even the circuit board up behind the glove box (which is currently out to check it again!), but it just doesn't want to behave.

 

How much do you have to remove to say a system is no long fitted and functioning on the car for the MOT? I thought if I remove the abs ECU, relays, fuses and power to the abs bulb and anything else that is easily removed, would that be enough to satisfy that it is not a functioning part on the car? I don't really want to take off all the sensors at this moment in time.

 

Hopefully I will know more this weekend what's still up with mine.