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Looking for the ref of the ABS control unit on a 1996 S4s - Suspension/Brakes/Wheels/Hubs/Steering/Geo - The Lotus Forums Jump to content


Looking for the ref of the ABS control unit on a 1996 S4s


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Hi everybody !

some problems since 2 months with the brake system, the "anti-lock" tell tale was flashing light regularly, sometimes continuous light (meaning no-abs braking),

now the parking brake tell tale is continuously light, meaning non-power assisted non-abs breaking remaining only on the front wheels... believe me it's very dangerous to drive in these conditions !

it seems the ABS control unit need to be changed ?

does anyone have an idea of the correct ref ? it's for a 96 Esprit S4s,

Thx, have good day, + Grandsport

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Hi everybody !

some problems since 2 months with the brake system, the "anti-lock" tell tale was flashing light regularly, sometimes continuous light (meaning no-abs braking),

now the parking brake tell tale is continuously light, meaning non-power assisted non-abs breaking remaining only on the front wheels... believe me it's very dangerous to drive in these conditions !

it seems the ABS control unit need to be changed ?

does anyone have an idea of the correct ref ? it's for a 96 Esprit S4s,

Thx, have good day, + Grandsport

Hi

Have never heard of the hand brake light reamaining on unless its a separate issue and is just a stuck switch on the hand brake itself,i have accidentally driven (as i suspect we all have at one time or other)with the handbrake still showing the light on and had no adverse consequences to the abs system,your flashing abs light sounds very suspiciously like a failed pressure switch,can you hear your pump running?does the pump cut in and out? a flashing abs tell tale light doesn't mean you have lost abs assistance it means you have a problem that needs looking at ,where as a solid light would mean an abs failure.(and the syetem would revert to a normal system without abs asisstance) Your braking system will still work so long as you have your pump running,even with out pump running you would still be able to stop safely,the system does not just fail removing all braking from car,you would still get roughly 30 brake applications before you lost all braking.

So in short check your pump is running do this by switching ignition on ,hand brake off ,and pump brake pedal until you feel the pedal go all "wooden" at this point you should hear the pump cut in and run for approximately 30-40 seconds and then stop.if your pump is running continuously or not al all suspect presure switch.Before you even think about replacing abs ecu get an OB11 reader on it (but remember the reader usually defaults to accumulator and ecu ,when it doesnt know the answer) Check all wheel sensors,connections get dirty and corroded,.check handbrake switch,if your handbrake was indeed "on" you would get a smell of burning brake pads (from the rear),do the rear wheels get hot? Check for leaks? check the brake switch (on brake pedal) has not fallen off or gone out of adjustment,are the brake lights constantly lit? Well thats my pennies worth someone may have other ideas but just checking these items will narrow down the troubleshooting,let us know how you get on.

Best regards

Nick S4s

Simplest things first.

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Nick S4s

Hi ! Thx Nick 4 your answer,

What I know :

1. The pump is not running at all

2. The ABS tell tale is continously light

3. The handbrake tell tale is continously light (and not related to the handbrake itself),

2 & 3 meaning (cf the owner manual) non-power assisted non-abs breaking remaining only on the front wheels,

--> My S4s brakes like a bike...

1 month ago we succeed in solving the problem with just renewing the brake fluids, but the problem came again last week,

rear wheels doesn't get hot,

no leaks,

brakes lights r ok,

Any idea ? Where is located the pressure switch ? Thx, + Grandsport

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Hi ! Thx Nick 4 your answer,

What I know :

1. The pump is not running at all

2. The ABS tell tale is continously light

3. The handbrake tell tale is continously light (and not related to the handbrake itself),

2 & 3 meaning (cf the owner manual) non-power assisted non-abs breaking remaining only on the front wheels,

--> My S4s brakes like a bike...

1 month ago we succeed in solving the problem with just renewing the brake fluids, but the problem came again last week,

rear wheels doesn't get hot,

no leaks,

brakes lights r ok,

Any idea ? Where is located the pressure switch ? Thx, + Grandsport

Ok so you have no pump running at all? that seems to point to the presure switch,as Olaf said the switch is located r/h side of bonnet on accumulator / pump assembly cant miss it ! I dont understand why your handbrake light is constantly lit unless the handbrake switch itself is bad,or does the handbrake light also indicate low brake fluid level ? I understand that if you loose the abs side of the braking system ,it reverts to just normal braking (ie No abs ,but brakes will still work) But cant understand why your car only brakes the front wheels i just dont see how that can happen,anyone got any ideas?unless you have a serious abs manifold problem and one or more ports are blocked with sludge, "o" rings,debris etc

If your pump doesnt run at all you will effectively have no brakes ,purely your foot pressure,the pump/accumulator act as a "hydraulic power supply" hence no supply=no brakes. Have you tried pumping brake pedal up to say 30-40 times untill pedal feels "wooden",at this point turn ignition on, the pump should cut in and "top" system pressure up to operating presure,no abs fail lights should show.I think that if i remember correctly a steady abs fail light indicates that abs system is disabled and therefore reverts to "normal" braking,a blinking abs light means that abs still works but it has detected an anomaly (this is normally in my exoerience a failed pressure swtch).Replacing brake fluid is a good idea but did you bleed the system?(to bleed system use a power bleed,its a right pain to bleed manualy and not always sucessfull) if you have air in system this could well be your culprit but would NOT account for pump not running.Hope this is of some help,maybe someone else has other ideas?? Did you manage to get a reader to read what fail codes the abs ecu has recorded??

Nick S4s

Simplest things first.

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  • 4 months later...

Hi,

to give a feedback the problem was solved after changing the ABS control unit and the pressure switch,

thx for your help !

+V

Hi,

to give a feedback the problem was solved after changing the ABS control unit and the pressure switch,

thx for your help !

+V

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