P38A Brake light is permanently on

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@Frank_38 You didn't say if it's the Brake Lights on the back of the car or Brake Warning on dash ?


ABS & TC are nothing to do with the brake light switch. ABS needs the pump to run & pressurise the system, hence the questions above about pumping the pedal & waiting for the pump to engage.

Nanocom will show you the state of the brake pedal switch, and also why the other lights are on.

From RAVE:
The Anti–Lock Brake System ECU (Z108) also has
diagnostic capabilities that allow it to detect faults
that may impair the system’s efficiency. If a fault
occurs, the ECU informs the operator of a problem
by illuminating the ABS or the ETC warning light.
The ECU also illuminates the warning light when the
ignition is first placed in position II. The ABS warning
light will remain illuminated until the ECU completes
a self check of the system. When the ECU sees all
wheels reach a speed of 7 km/h (5 mph), the self
check is completed and the ABS warning light turns
off. If a fault is detected during the self check, the
ABS or the ETC warning light will remain on and a
fault code will be stored in memory to aid in servicing
the system. When an ABS fault has been detected,
the message ABS FAULT may also display.
The fault code can be retrieved using a diagnostic
tester.
 
ok, I drove again. I can hear the pump every time I press the brakes - really every time.

And even when shifting into gear - but maybe I'm imagining it?
 
pwood999 said:
@Frank_38 You didn't say if it's the Brake Lights on the back of the car or Brake Warning on dash ?


ABS & TC are nothing to do with the brake light switch. ABS needs the pump to run & pressurise the system, hence the questions above about pumping the pedal & waiting for the pump to engage.

Nanocom will show you the state of the brake pedal switch, and also why the other lights are on.

From RAVE:
The Anti–Lock Brake System ECU (Z108) also has
diagnostic capabilities that allow it to detect faults
that may impair the system’s efficiency. If a fault
occurs, the ECU informs the operator of a problem
by illuminating the ABS or the ETC warning light.
The ECU also illuminates the warning light when the
ignition is first placed in position II. The ABS warning
light will remain illuminated until the ECU completes
a self check of the system. When the ECU sees all
wheels reach a speed of 7 km/h (5 mph), the self
check is completed and the ABS warning light turns
off. If a fault is detected during the self check, the
ABS or the ETC warning light will remain on and a
fault code will be stored in memory to aid in servicing
the system. When an ABS fault has been detected,
the message ABS FAULT may also display.
The fault code can be retrieved using a diagnostic
tester.
Click to expand...
...Brake Lights on the back of the car
 
I found something here from 2016:

"If it runs every 2-3 pedal pushes, it is tired.....if it runs on each press of the pedal, the accumulator is finished and needs to be replaced....you MUST use the RAVE method of de-pressurising the Accumulator before removal."

P38A - ABS & Traction Control Fault (2001 P38 4.0)

Hi everyone, I need some help. I've just got my P38 back from a "landrover specialist" after over 3 months, long story, but they were changed the wheel bearings and fixed the head gasket, but buggered the electrics and ended removing my LPG system along the way. Anyway, now its showing ABS...
www.landyzone.co.uk

which "the accumulator"?

in my case, the pump starts every time the brake is pressed.
 
Yes, you have two issues. Brake lights on rear will either be the switch, or a BECM issue. Most likely the switch.

Before you replace the Accumulator, check pump is fully pressurising.

With car stationary wait for the pump to stop running. Then drive forward until you're over 5mph (without using brakes), and the lights should go off. ABS ECU needs to see wheels moving or the lights stay on.

If that works, then you just need a new accumulator. If the pump doesn't stop running, then either the pump or pressure switch is bad.
 
pwood999 said:
Yes, you have two issues. Brake lights on rear will either be the switch, or a BECM issue. Most likely the switch.

Before you replace the Accumulator, check pump is fully pressurising.

With car stationary wait for the pump to stop running. Then drive forward until you're over 5mph (without using brakes), and the lights should go off. ABS ECU needs to see wheels moving or the lights stay on.

If that works, then you just need a new accumulator. If the pump doesn't stop running, then either the pump or pressure switch is bad.
Click to expand...
...the lights don't go out.
Started the engine, waited until the pump goes out (slight buzzing stops). Then drove off for a long time without braking - nothing happens, the TC and ABS lights stay on.

Could it be that I have destroyed it by stepping too hard on the brakes?
When I changed the switch, I stepped very hard on the brakes 2-3 times - the engine was off.
 
For the TC & ABS lights you need to check the ABS system. That includes the booster pressure switch, wheel sensors, ECU diagnostics, etc.

No you would not damage the ABS by stomping on the brake pedal. It generates 80bar, so a lot more than your footsie can provide !!

Brake switch & lights are a separate system, although the brake switch status is sent to the BECM & ABS to inform them when you press the brakes. As I said above, to check the switch, either use a Nanocom, or get a helper to tell you if the brake lights go on-off when pressing the pedal !! Otherwise lean a mirror against a wall so you can see the brake lights from driver's seat like MOT centres use !!

1741550428005.png
 
Frank_38 said:
...the lights don't go out.
Started the engine, waited until the pump goes out (slight buzzing stops). Then drove off for a long time without braking - nothing happens, the TC and ABS lights stay on.

Could it be that I have destroyed it by stepping too hard on the brakes?
When I changed the switch, I stepped very hard on the brakes 2-3 times - the engine was off.
Click to expand...

There are 2 contacts in the brake switch. Sometimes one comes loose and that's when both switches show as on all the time.
 
Yes, here's where the other brake pedal switch goes. But neither brake switch is required to close for ABS & TC lights to go out when moving off from standstill.

1741599057322-png.336816
1741599077629.png
1741599103357.png


1741598773138.png
 

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Many thanks for your support.
I would like to describe the process once again, as it can't really be a coincidence.

I've only had the EAS problem so far - that's solved.
Then the car was absolutely faultless.
I was then informed that my rear brake light was permanently on - at this point I also had no error in the display.

then i removed the switch and reinstalled it. The brake light now works perfectly, but at the same time (i.e. directly after installing the switch) ABS and TC appeared in the display - that can't be a coincidence, can it? I haven't changed anything else!
 
You need to figure out why the pump runs on every press. If the accumulator (black sphere) is old then that's the likely cause. Or it could be pump/pressure switch problems
 
I'll ask again anyway: it can't be the switch, or should I buy a new one and replace it?

and yes, I will take a look at nanocom and probably buy it.
 
Frank_38 said:
Many thanks for your support.
I would like to describe the process once again, as it can't really be a coincidence.

I've only had the EAS problem so far - that's solved.
Then the car was absolutely faultless.
I was then informed that my rear brake light was permanently on - at this point I also had no error in the display.

then i removed the switch and reinstalled it. The brake light now works perfectly, but at the same time (i.e. directly after installing the switch) ABS and TC appeared in the display - that can't be a coincidence, can it? I haven't changed anything else!
Click to expand...
Unfortunately, it can be coincidence, just had 2 unrelated problems on one of my P38's
Either the accumulator is knackered or the pressure switch is opening before the correct pressure has been reached. My money is on the accumulator.
 
Last edited:
Datatek said:
Unfortunately, it can be coincidence, just had 2 unrelated problems on one of my P38's
Either the accumulator is knackered or the pressure switch is opening before the correct pressure has been reached. My money is on the accumulator.
Click to expand...
+1 replace the accumulator. If you don't know when it was last done then it's overdue anyways. They don't last forever
 
...looks like this:

Can you recognize anything?

and which manufacturer can you recommend for the new device?
 

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Frank_38 said:
...looks like this:

Can you recognize anything?

and which manufacturer can you recommend for the new device?
Click to expand...
The black ball shaped object in the pic is the accumulator. 30 presses on the brake pedal, with the engine off before you try to remove it. If all the pressure has gone, should unscrew quite easily. No bleeding needed after fitting.
The same accumulator is used on a number of cars, so I go for the best price.
 
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