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Hardly any brakes

4K views 17 replies 7 participants last post by  John W 
#1 ·
I took the car out this morning and when I got back the accumulator kept running for a good 40 seconds even after switching the ignition off and removing the key. When I went out a little later the brakes were terrible they were really spungy and had to be pumped a bit before they worked or they had to be pressed really hard to get the car to stop.

I am doing a 1000km journey next week so would like to have this problem sorted by then

PLEASE HELP
 
#4 ·
JeremyD said:
My pump usually used to run a little while after I turned off say 5 seconds or so. Would a burnt out relay account for the brakes being spongy
My pump has never run after engine shutdown and I dont think it should.Hopefully one of the wise ones will confirm/deny this.
If the pump is not performing to spec it will battle to pressurize the accumalator and your brake pedal will feel abnormal.
I presume you have checked for leaks as this will cause more frequent pump activation and will also give a spongy brake pedal until pressure is restored.
 
#6 ·
Out of interest how often should the pump run? Mine seems to run when I first turn the keys in the ignition - the length of time varies. It never runs after switching off.

It does sometimes run during pressing the pedal -not sure if it always does?
 
#8 ·
It should definitely not be running while the key is in the off position. Your culprit is most likely the relay as previously stated. It can cause the pump to run too little and cause the lights to come on along with limited braking power, or it can cause your pump to just continually run until it destroys itself.
 
#9 ·
I swapped the yellow ABS relay with the one below I think it is for the windscreen wipers or something they are exactly the same but no luck, I do know there is another relay for the ABS that is black and is the only one like that in the fuse box. I will try the local auto electrician and see if he has any. Am I correct in assuming that there is no way of testing the relays with a multimeter I did check the yellow ABS realy for continuity and found it accross one channel but no the other
 
#11 ·
It sounds to me like you've been driving around w/ a bad accumulator for awhile. The brake probably felt spongy because you probably never got the desired pressure in the accumulator. The combo 3 lights that you've mentioned pretty much indicate a major ABS system fault. It's possibly a burnt out ABS relay or the ABS pump engine seized from continuous operation.

If I remember correctly, ABS relay is different from the others. I only know from a pricing perspective, but whereas yellow or green relays can be had for $10, black ABS relay costs around $50.

It's not a easy job, but if you take out the engine from the ABS pump, you can see if the motor is seized by turning the armature by hand. If it's not turning smoothly, it's time to get a new armature/brush. FYI, lrscott recently did a great writeup on this fix, so you should refer to his writeup.
 
#13 ·
I depressurised the system by pressing the brakes about 60 times then I disconnedted the EAS compressor and strted the engine up. I cant hear the ABS pump running and also cant feel it running this leads me to two conclusions either the relay is gone or the pump is burnt out how do I test to see if there is power reaching the pump to rule out the relay?
 
#14 ·
Ok worked out how to test, I measured 12.58v running into the ABS pump at start up and also measured and got continuity accross the pumps two power lines.The relay should be fine then if there is 12v running in and so should the pump if there is continuity or am I wrong about the pump? I would like to remove the pump and have a look see but I dont want to render my braking system useless because of the upcoming journey I need to make.
 
#15 ·
JeremyD said:
I depressurised the system by pressing the brakes about 60 times then I disconnedted the EAS compressor and strted the engine up. I cant hear the ABS pump running and also cant feel it running this leads me to two conclusions either the relay is gone or the pump is burnt out how do I test to see if there is power reaching the pump to rule out the relay?
The power relay to the pump is RL17 in the engine compartment fuse box.If you take the relay out you should see numbers next to the pins underneath the relay.
Pins 30 and 87 (according to rave) are the contact pins which feed 12V to the pump. if you join the correesponding pin sockets in the the relay socket together,then the pump should run.(with the relay out of the socket).You may need to have the ignition on and engine running.

This will check the wiring from the relay to the pump and the pump.If pump does not run,then either it is u/s or the wiring is.
to check the wiring you coild run a wire straight ffrom the battery to the 12v pin on the pump motor.Be careful not to touch the bodywork with the end of the 12v wire as it wont be fused and will try to weld itself to the body.(earth of vehicle)
 
#16 ·
JeremyD said:
Ok worked out how to test, I measured 12.58v running into the ABS pump at start up and also measured and got continuity accross the pumps two power lines.The relay should be fine then if there is 12v running in and so should the pump if there is continuity or am I wrong about the pump? I would like to remove the pump and have a look see but I dont want to render my braking system useless because of the upcoming journey I need to make.

The pump could be seized ,so you will measure continuity across the terminals but it wont turn with 12V applied.
Also the relay contacts may be burnt,so although you see 12V across the motor terminals the resistance of the burnt relay contacts may not allow sufficient current flow to drive the motor.
 
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