Okay, I know this ain't good!
During the past two times I have driven it, ccasionally when I apply the brakes the yellow ABS light flashes for the duration that my foot is on the brake pedal.
Any thoughts appreciated!

Quentin

 

would it be the fluid level indicator, this would happen on my partners car only when braking

 

Now I am feeling foolish for not immediately checking it. The level was fine a few weeks back, and no signs of catastrophic leak.
Will check it!
Thanks

 

I believe the red brake light is tied to fluid level, not the yellow abs light.

 

To clarify, does the light actually flash or does it turn on while pressing the brake pedal?

 

It flashes for as long as my foot is on the brakes. Brakes feel fine. Has done it periodically maybe 3 times to date, so am waiting for it to become more frequent as whatever is malfunctioning dies.

 

OK that is strange. Several faults will cause it to turn ON, none that I am aware of are supposed to make it flash.

Is your Accumulator original?

 

It was replaced 12m ago with a used one. Fine until now. It does seem to be a regular pulsing flashing, as opposed to flickering

 

When the car hasn't been used for a while, do you hear the abs pump come on and build pressure, then shut off?

If yes, how long does the pump run?

 

Haven't noticed. Unfortunately car not parked at my house. Will check next time I use it. I forget - I should hear the pump working when I switch on the ignition?

 

So......... ABS pump runs for 30 sec after turning ignition on. I can pump the brake pedal 3 times and then it kicks in again. I am thinking time for a new accumulator?

 

Yes I would suspect the accumulator, particularly since it was replaced with a used one. Even NOS might be problematic depending on when it was manufactured.

I replaced mine with a Bosch accumulator that fits some Mercedes and Maybachs and is more widely available. Works great. Part number is 0265202070, and it used be about $70 on Amazon but the price has nearly doubled. Summit Racing says they'll special order if for you for $85.99:

https://www.summitracing.com/parts/bch-0265202070

 

Quentin,

I'd suggest a 30sec pump run from cold, and then a recharge kicking in after 3 uses of the brakes is absolutely fine. Very similar to my own. I wouldn't be looking to change the accumulator based on that.

I would start by doing a blink test on the system to verify what fault codes have been thrown by the system as a result of the light coming on.

It's very speculative but I wonder if a pulsing light could be indicative of a failing wheel sensor? Is the flashing frequency influenced by the speed of the car when you touch the brakes?

Anyway, let us know what codes it shows.

Cheers

Paul

 

Awesome....... thanks!
Yes, I was just looking at the very same one.

 

Paul,
Ahhhhh......... a different opinion!

The flashing only occurred occasionally, so not sure if the pulse rate is proportional to vehicle speed or not.
Will do the blink test as you say when I return from a work trip at weeks end.
​​​end. Thanks!

 

I just went out and timed mine from cold (several days) and pump stopped at 23 secs.

Here is what can trigger the yellow warning light:



It's the flashing or intermittent nature that makes me suspect the accumulator is getting tired. Most of the above will fully light the ABS warning, the other possibility is an intermittent wiring issue. I don't usually recommend throwing parts at a problem, but while the Bosch accumulators are still available at a reasonable price it might be worth eliminating that as potential cause, and knowing you have a good unit that you won't have to worry about for years.

But agree with Paul that you should see what codes flash first.

 

So I had my diagnosis process mixed up. I gather a tired accumulator is indicated by 3-5 pumps for the pedal to go hard (ign turned off), not 3-5 pumps for the pump to reactivate (ign on).

 

Hey, thanks for clarifying and for the fault descriptions. Agreed, the flashing seems weird. Again, it seems to be rhythmic pulsing as opposed to an intermitent short.

 

So...........
I went in search of what I believe is the elusive brown connector which I need to short in order to do the ABS blink test. No sign of the connector?



I also let the ABS pump fully charge the accumulator (30 sec), then turned off the ignition. Got 35 pedal strokes before the pedal went hard. Seems the accumulator is healthy.
Am I correct in thinking some cars didn't have the ABS ecu brown connector for doing a blink test?
If so, what next? 😞

 

Quentin,

It'll be a taped up part of that wiring loom which ultimately is attached to the ABS wiring plug. Carefully examine the wiring back from the plug and there's a taped up bit. I can see one taped up bit in your photo, but can't see the colours clearly enough to see if it is the right one.

Also got your PM and I'll send you the doc tonight.

Cheers

Paul