Harry, Thanks, I'll give it a try. One thing that does concern me is that when I took out the old sensor I was forced to drill it, which was a long job. I was careful not to drill too deep for fear of taking the drill through to the hub. Unfortunately, a piece of the old sensor fell through the gap. I'm hoping this will not affect the operation.

Larry

Ok car won't start now at all. Just took it out of the garage this morning and it started fine. early evening, nothing. It turns over (like a clicking sound) but won't fire up.
Tried jump start, admittedly from a small Fiat Panda -- possibly battery is too weak to make a difference.

Any thoughts on where to start. I did notice early a whirring sound when turning on the ignition to test the ABS sensors with my meter, but it just sounded like the lifter fuel pump trying to activate.

Any idea where to start looking?

T4 will see ABS problems as a fault, and anything causing low speed ABS actuation will be logged.

I had cause to sort out exactly the same type of fault on a V8 recently (I know I know) and T4 reported incorrect toothed wheel fitted to one or more wheels.......the cause, well how the owner chortled after he had replaced both front wheel bearings, both front discs and pads, and both rear hubs in an attempt to cure this issue........I said to him have you had any tyres fitted recently? yes came the reply, why's that?

On inspection there was a different profile tyre on one corner :getmecoat:

It's not always about what information is presented to you, it's how you interpret that information ;)

Brian :D

Yep, stick your battery on charge ;)

Were the headlights flashing when you attempted to start the car? this is the fabulous way these cars tell you the battery is discharged :)

If not, have a look for starter motor solenoid contact replacement ;)

Brian :D

Hi Brian.
I had the same problem pulsing no light but T4 still gave a reading and indicated rear right plausible, turned out to be the bearing and a very nasty back plate corroded, which was cleaned for the time being :o this still as to be rectified when I can sort out the time.

It also showed other possibilities as you can see from the pics below. ;)
Arctic

PS Operator I am not yet, as I am still in training :D

Marina, Arctic,

Duuurr -- It was the battery, I'd left the ignition on too long when running the ABS sensor tests. Charged and OK now.

Thanks for the responses on the tyre option. I just had all 4 tyres changed, all the same profile, all Firestone with the same pattern, so I'm quietly confident that one hasn't caught me out.
The front right sensor I changed as it was the speedo that went first, but miraculously came back on.

When I ran the tests with my meter on the two rear sensors (after taking the back seat out - stupid to hide the sensors under the seat but there you go), they both registered very uniform changes in the voltage on the signal wire when rotating the wheel slowly and marking each change in the voltage - all were equidistant and no breaks or missed changes in the voltage.
I also had the back hubs off and cleaned everything up including the back plates and the stubs and around the bearings.

The test of the front right was markedly different with no responses to voltage on about 1/6th the circumference of the wheel. This seems consistent with the original fault (speedo dying and ABS warning light on).

I'm going to double check the length of the new sensor as suggested by Harry, but I am coming to the conclusion it is the front right wheel bearing that needs changing.

Anyone got a youtube link for this on an MG ZT-T?
The bearing, with integrated reluctor magnetic ring is about £40, but I don't have a press to get the old one out of the hub or the new one in and I don't want to bodge it with bolts and nuts as indicated for fear of damaging the part.

Regards Larry

No further forward with ABS problem
 

This is driving me crazy, so much so I'm thinking of junking my MG ZT-T due to what appears to be some kind of design fault with the braking system.
Why?
Well I've checked what seems to be everything and I'm still getting the judder on the brake pedal at low speeds.
I've checked the voltages on the back hubs, and cleaned up the back plates to make sure nothing is blocking the senors.
I've replaced the front offside sensor, as it was the speedo that went initially. I did a voltage check on all the wheels and the voltage changed equidistantly on all wheels except the front offside which had no response on about a 6th of the wheel circumference so I thought that's it, change the wheel bearing. Did that, same problem.
Put new front discs and pads on at the recommendation of the garage, as no ABS faults were showing on the test after the old one's were cleared and I test drove it braking 20 times with judder.

So now I have no ABS light, and no ABS faults, yet still I'm getting the judder after replacing a sensor, a bearing and front discs and pads.

Where does one go from here?

HI Larry.
You really need to get this on a T4 in my opinion to move forward, whom is closest to you ( larryr123 ) ? where is that place.

A few weeks back a nano member had the same trouble, he changed the sensor after drilling it out, all was ok passed the initial test but he still had pulsing at the brake at low speeds.

It lasted for a day and the ABS then reverted back to no speedo etc, we decide to remove the hub and replace it with one we had spare and hey presto all was ok, what we did notice was the debris left behind from drilling may have damaged the magnectic ring

So therefore you replacing a new wheel bearing it should have been ok, is the speedo working ok, if so then it could be one of the other bearings ie the rear OS etc

Remember it is the side of the senor which reads the ring in the bearing not the tip of the senor on the front, the rear sensors use the tip of the senor.


Note the magnet ring missing
http://i66.tinypic.com/28rfv5t.jpg1

http://i66.tinypic.com/iwua7n.jpg2


You can see the black magnet ring on these below,
http://i67.tinypic.com/a0ky1v.jpg3

http://i68.tinypic.com/wtxi7q.jpg4

You can see now how if you drill out the sensor how easy it is to damage the ring, when dealing with the front ABS I would remove the diss etc to make sure all is clean, do this even if you are only changing the sensor.

It is best if you have to change the front sensor that you try and remove with out drilling first, if you do need to drill it out snap the sensor off flush once the bolt as been removed, drill down the centre about 12mm with a 3mm drill then screw in a wood screw with a flat head & domed top, you can then prise out the section of the sensor using a claw hammer or pry bar with a fork cut into it, but this will only do you any good if it is the senor in the first place.

To be honest most of these sensors are robust and most of the time it is the magnetic rings that fail, or pic up rust particles etc

As I said above at the beginning T4 will pinpoint your problem for sure.

Arctic thanks for the input
 

Arctic thanks for the description and the graphics.
Originally the speedo went and the ABS light came on, that's were it all started.
I had T4 run at a garage, which pinpoints faults to each wheel but doesn't tell you what the problem is.
I diligently tested the changes in the voltage with my voltmeter and pin connections in each sensor lead and the break in continuity was on the front offside.
I had already drilled out the sensor and replaced it. I then replaced the wheel bearing making sure to get the magnetic ring in the right way round as per your photos.

I have a working speedo and all old ABS faults were cleared. I tested it with 20 or so brakes (with judder) on a run and plugged in the T4 again and no faults came up.

Judder is still there.
I changed the rear hubs at end of 2014, and they all had equidistant markers on the wheels as I tested the voltage readings. I also cleaned up the back plates to make sure there was no blockages between the rear sensor tips and the rear hubs, and cleaned around the hubs generally.
Also put new discs and pads on the front so it's not a disc deformity issue.

Mystery -- done everything I can think of.

Larry

Where am I
 

"whom is closest to you ( larryr123 )"

Arctic, I'm in Bedford.

Regards Larry