ABS and ESP units

note that the ABS/ESP is complicated
I have no knowledge of these units, so rely entirely on comments from others

 Excellent short video on how ABS works 

 Excellent video on ESP anti-skid control 

 Excellent article about ESP faults and repairs 

The ESP can be turned on/off by the switch on the dash-board

Circuit diagram

Many units contribute to the successful operation of the ABS/ESP functions!


Location of units

Shows the location of the ABS/ESP unit near the battery; access may be easier from below - remove left front wheel and mudguard under wing

This is the ABS block; CAN-VAN version.  According to the parts list, it needs to be configured

Shows the location of the yaw sensor (accelerometer) under the handbrake lever

Remove the plastic cover under the handbrake to locate.  It is held in place by one (maybe two) bolts.

ESP warning lights on "ESP Not Functioning"

You can turn ESP off - but it still leaves a light and would be an MOT failure in the UK.  In any case it should turn back on automatically after the car reaches speed over 20-25mph (30-40km/h)

As the fault could be in the ABS/ESP unit or the ABS sensors on the wheels (or the wiring in between!), a good diagnostic tool will tell you whether it's a sensor outside the unit or a faulty ESP unit.

William Wadling's local garage diagnostic found a fault with the yaw sensor (accelerometer) under the handbrake (see above).  You can purchase off the internet: second hand about £40 reconditioned about £80.  Local garage charged £135.00.  Now working OK.

Yves de Muyter points out that there is also a sensor that measures the angle of the steering wheel.  Using PP2000, Rimas Baltrusaitis did a calibration of the "steering wheel angle sensor" and the "ESP/ASR not functioning" light on his 1007 dashboard went out.

The ABS unit is quite low down - it could have corrosion in the plug/socket over the years so unplug and check.  I had a fault like this on my Jaguar, water leaking in over time - the plug/socket was quite a mess when I eventually discovered the fault.

You can replace an ESP unit with a used one from another car - some UK based companies re manufacture these units.

If replacing with used one, make sure the type fits your car, as there are 2 versions of this unit.  Variant 1 with external braking pressure sensor and variant 2 with internal pressure sensor.  Look for the code on the unit pump.

Thread about ABS unit which may be helpful:

I have no knowledge of this unit so am reliant on the knowledge of others.

Stephen W Wood: Have had to put my 1007 into a friends garage due to ABS and ESC light being on and diagnosed as ABS pump.  This has been changed, but it now looks like the master cylinder has failed!

Neil Gibson: Did they change the valve block? Usually the fault lies with the ecu and the valve block needs no interference.  If they changed it then it will need bleeding properly using pp2000 software.

Stephen W Wood: I'm told that the unit was changed and the warning lights have gone out but there is no solid pedal.  I'm not overly surprised at that.  I think replacing that will solve the problem.

Neil Gibson: My bet is they haven't bled the system properly.  Use pp2000 and you can actuate the ABS pump to bleed the valve block.

Stephen W Wood: A pressure bleeder has been used.

Yves De Muyter: The pressure bleeder probably doesn't do the job hence why there is software to open the valves in the abs unit...

Neil Gibson:  Correct!

Another thread about the ESP light remaining on which may be helpful:

Neil Gibson:  Fault codes are needed for this one, and a comprehensive reader which will read all ecu‘ s and not just the data from the OBD socket.  The Peugeot PP2000 can be bought on ebay.

Traction control (esp) relies on data from the abs, restraint system, engine management system etc.  Any fault which could affect the esp ability to take control will result in the system closing down.

If you have fault codes which keep returning even after parts have been changed or more suspicious, if you have multiple faults, particularly from the abs, then I suggest the abs module is faulty.

Buy a used ABS, put the block and pump to one side and swap the ecu over.  The ecu's are susceptible to water damage.  Unless you have PP2000 to reconfigure the module make sure it comes from the exact same car.  Engine size, wheel size and transmission type are all programmed and must agree.

Further thread about ABS unit which may be helpful:

PP2000 came up with the fault: ABS recirculating pump fault, pump locked, CO, CC or CC+ - is it right to assume the ABS pump has failed?

Neil Gibson:  Sounds like the abs pump motor.  Go to “actuators” in PP2000 and power up the pump - it’s the round thing attached to the ABS module.  You should hear it run.  Try tapping it.

Tried a gentle tap whilst trying to run the pump and planet says "operation not possible".

Neil Gibson: Could be the connection block on the module.  Or - It’s easy enough to remove the motor from the ABS block to clean.  More often than not the abs module itself is faulty.