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Ross
Ross, Diagnostic and repair technician
Category: Car
Satisfied Customers: 1180
Experience:  Licensed diagnostic and repair technician
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04 Zafira 2.0DTi Life abs traction control light came on

Customer Question

04 Zafira 2.0DTi Life abs traction control light came on together, wife didn't notice it but when I drove for the first time last week I noticed they were on. I checked all fuses pertaining to abs / traction crtrl all ok went to carquip a specialist Vauxhall breakers and they put there OEM Vauxhall fault code reader on the car and diagnosed a r/h rear wheel sensor. I replaced two from the breakers to no avail so opted for a new one replaced that today, fault lights still on, took it for a road test over 40Mph abs does not operate. There is a voltage down to the abs plug and only two pins at the plug. To me this indicates a "S" line to the plug. Maybe it could be the modulator as the abs is inoperable. Any ideas please John P XXX

Submitted: 2 years ago.
Category: Car
Expert:  Ross replied 2 years ago.
Ross :

Hello and thanks for trusting me to help you today. I am a licensed diagnostic and repair technician, I look forward to working with you.

Ross :

Firstly, if not already done ensure the fault codes have been cleared from the ABS system since the sensor has been replaced, the ABS system will store a permanent fault code until it has been re-set regardless of whether the fault still exists on the system. This has non volatile memory, so it needs to be cleared with a fault code reader, disconnecting the battery will not re-set the control module. The ABS will be totally disable when the warning light is on.

If this has been done, start with the wiring as this is fairly common. These are an inductive sensor which induces its own current which is detected by the control module. If there is voltage to the sensor from the module this is the exciter voltage to start the induction process, because this is inductive the circuit is not negative earth so it is important to check the continuity between the ABS module wiring connector and the ABS sensor connector on both black and brown wires. DO NOT Test continuity of the wiring while connected to the sensor as this will damage the sensor.

Ross :

The only safe method if testing the sensor is using an oscilloscope but if you don't have one of these, we can assume the sensor it's self is OK as it has been replaced. If the wiring has continuity between the sensor connector and ABS Module connector, it only leaves the ABS control module. Check the pins on both sides if the connector at the ABS Module as they can suffer water ingress and corrosion causing signal loss.

JACUSTOMER-77i0q3cm- :

Hi Ross, The fault will not reset.

Ross :

Ok, if it won't clear move on to the wiring as I mentioned above and go from there. If it cannot be cleared it indicates a fault with either the wiring or control module

JACUSTOMER-77i0q3cm- :

Hi Ross, The voltage is coming from the modulator to the sensor plug connection point and I have not tested the sensor as I believe it to be a phonic wheel type system. I disconnected at the sensor and the put my multi meter on the two terminals at the cable plug that attaches to the sensor socket and this is where I got the voltage readings.

JACUSTOMER-77i0q3cm- :

I also disconnected at the left and right splitter connection and did the same test again

Ross :

Great ok. So that would rule out wiring problems if you get current on the two pins. So this points to the control module. In which case it may have failed internall which is keeping this fault on. I have seen part of the wheel sensor circuit burn out which keeps this code from clearing.

JACUSTOMER-77i0q3cm- :

Hi Ross, Are we therefore saying that the control module is at fault and if so, is it part of the modulator and pump assembly where the brake pipes attach to the body of the modulator.

JACUSTOMER-77i0q3cm- :

I have a circuit diagram from my Haynes manual to assist me

JACUSTOMER-77i0q3cm- :

the right rear sensor loom states on the diagram to be at modulator pin 1 bl/rd and pin 2 bl/rd with a brown (br) screen to connector B for pin1 and A for pin 2 at the sensor break point. It is at the break point connector to A-B sensor on the loom is where I took the voltage

Ross :

Yes that's the one, there should be a black plastic box as part of this, you can replace just this to save having to undo the hydraulic connections

JACUSTOMER-77i0q3cm- :

for pin 1 read Br/Rd and pin 2 Bl/Rd

Ross :

Yes, brown and black both with red tracer according to my diagrams

JACUSTOMER-77i0q3cm- :

By removing one of the fuses the pump as well as the radiator fan operates. as an aside, from the diagram there is a 10A fuse which feeds into the modulator (F23) into pin 15 and (F38-10A) into pin14 via the brake light switch( brake lights work) and (F5-60A) into pin 18. all fuses appear to be ok. Does this multi-pin connector block cause much trouble or would it be more advantageous to replace the complete assembly? where is it the most accessible to replace, under the car or over the engine/battery area. For the last MOT I had to replace the brake pipes on both front wheels.

JACUSTOMER-77i0q3cm- :

It was tight but accessible

JACUSTOMER-77i0q3cm- :

Hi, you still there?

JACUSTOMER-77i0q3cm- :

Because I work away from home this has to be right and the most efficient way to change it as my wife needs the car for grandchildren duties, sorry for being a pain.

JACUSTOMER-77i0q3cm- :

Therefore, is it easier to change it from the top or below?

JACUSTOMER-77i0q3cm- :

my email is *****@******.***

JACUSTOMER-77i0q3cm- :

Hi Ross

JACUSTOMER-77i0q3cm- :

Have you finished with this chat review?

Ross :

sorry for the delay. Personally I prefer to access these from underneath. I doubt this would be a fuse issue as it shouldn't cause one fault code like it is. I would check the connector to the control unit and if it's all clean inside with no signs of corrosion, replace the control unit.

JACUSTOMER-77i0q3cm- :

Does this connector have a lever type disconnect device just behind the battery area/

JACUSTOMER-77i0q3cm- :

How can I find the pin idents as there are two banks of pin connectors?

JACUSTOMER-77i0q3cm- :

If this is the case then I may have to replace the complete assembly because the pins inside all show no signs of corrosion.

Ross :

Ok it sounds like you have the correct one, bare with me I will find the wiring diagrams for the pin out.

Ross :

Sorry that took so long.

Full Size Image


This is looking at the wire side with the connector disconnected. The two highlighted pins are for the rear left sensor.

JACUSTOMER-77i0q3cm- :

Thanks pins one and two on the right are for the right rear so I can check it out with a strong light tomorrow. What about the multi cable connector mine has a disconnect lever just to confirm I have the correct connector. you operate the lever and this disconnects the multi-plug in that right?

Ross :

Yes that's correct. The lever locks it into place.

JACUSTOMER-77i0q3cm- :

Thanks that's great, will get started tommorrow

Ross and other Car Specialists are ready to help you
Expert:  Ross replied 2 years ago.
Hi John, if you need further help just come back here and reply and I will get back to you ASAP. Good luck with getting the problem sorted! thanks, Ross.

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