Braking by itself

[mr_miyagi]

MK7 2012 140 sport fwd.

I'm currently trying to get to the bottom of a weird problem that I've discussed in other posts. "Help north wales" being the last one. I'm trying to use the van as little as possible but it's my only wheels so still need to get about.I set off this morning to go to work, it's a 10 minute drive so not too bad. I'd only moved a few yards when it just wanted to stop moving. It was as if someone had pressed the brake. The traction control light is lit up on the dash and the hill start assist has gone. Also the brake warning light is on some times and off the next, even though the pads aren't worn down to the wires. When it did this I looked down at the dash and the traction control light was flickering slightly. It only did it for a coupe of seconds and then it drove freely.

Today this has happened each time I've used the van, 3 times in total. Once to go to work, once to go pickup parts and once to go home. What the hell is going on?

[Airthies]

Have you had the codes read?
Even though the lights go off if it's had any sort of failure code it will be stored.

If it's only live "warning" lights there may not be codes stored but viewing/recording live data when the fault occurs will sho you the reason it is bringing lights on.

As a hunch I'd be looking for corroded plugs or damaged wiring.
Or poor earth points when we're dealing with a 13 year old stroppy teenage van.

[mr_miyagi]

I managed to find a local garage that would read the codes without charging me, and whilst he didn't give me specific code numbers he said "The only thing it's showing is a temperature sensor on the DPF".

So I fitted new sensors, there's two of them, and also checked the Vapouriser. The heat pulg was showing 1 ohm to 1.2 ohm, so apparantly OK from what I can find on the internet. When I pulled the fuel pipe off to clean the jet I found that someone had put a blob of weld on the end of the steel pipe. The same person that had removed the DPF and welded it all up, then re-mapped it with the DPF and EGR deleted. So I drilled that out and can blow through it ok.

I'd fitted an exchange ford DPF and I must admit, kind of hoped the sensors would be ok. I've had it put back onto a standard 140 map but left the EGR deleted. I should imagine it was just going to be failing MOTs the way it was, a noticable bodge up.

The traction control light doesn't come on when I first start it up. It only comes on once I start moving, mostly straight away but sometimes after I've gone 100 yards or so. But apparently no fault codes showing that say anything about it. I'll have a good look round it for any bad wires and earths.

[Airthies]

If it's only on once moving but no stored codes double check the condition of the stator (toothed) rings on each hub and give them a clean with a wire brush.
Check clearance between hall sensor and rings.
Check wheel bearings not excessively worn causing issues with reading the abs stator rings.

[DanMK7uk]

Will follow with interest, wonder if a bad wheel speed sensor could cause such behaviour….

[metalworker0]

if non of this is caused by anything electrical ..it will be deterioration inside the flexible hoses,, so acting like one way valves, or badly corroded areas that the pads locate on or dried up stiff slider pins.

or over-lubricated slider pins that are prone to sticktion.

what condition is the brake fluid in , when was it last changed. ..if changed at all, could be as old as the van.

Sure sign of this is dirty looking fluid in the tank.

all the best.mark

[sfnett]

Had a similar problem on 2008 lwb rwd ,when i first got the van i would pull off and sometimes the brakes would just engage but if i pressed the esp button before pulling away all was good, got it sorted with forscan , turned out the steering angle sensor was well out of calibration, reset it and all sorted.

[DanMK7uk]

Brake fluid not overfilled?

[mr_miyagi]

Thanks for the replies.

I had no idea these had steering wheel position sensors. I've fitted a new steering rack and a new offside driveshaft, along with new front discs and pads and new rear pads. I've not had chance to get it in to have the wheel alignment done yet so maybe that's causing it. The sensor rings on the driveshafts are all clean. I even counted the teeth to make sure the new one had the same as the old one. Took the sensors out and cleaned them too. The brake fluid does look a little dirty so I'll change it, but it's not that bad. Can't understand why the brake warning light comes on when it's new pads all round and the fluid is up to the max mark.

The brake warning light isn't on when I first start it. For the first few seconds the orange engine light is on, and the information light is orange with the message saying "Serive oil now". Which I'm guessing is just telling me it's due a service.

After a couple of seconds the information light turns red and it says "Engine malfunction". At the same time the brake warning light comes on.

If I put the ignition on I can press the ESP button on and off and the traction control light comes on and goes off. As soon as I move forward though the TC light comes on and stays on.

I'll book it in to have the tracking done and ask the lads nicely if they can read the fault codes and perhaps give me a list of what's going on.

I've been going through some of the earth points, cleaning them up. The one under the PCM was quite rusty. Seat's out tomorrow to have a look at that one.

[knobby1]

Thanks for the replies.

I'll book it in to have the tracking done and ask the lads nicely if they can read the fault codes and perhaps give me a list of what's going on.

I've been going through some of the earth points, cleaning them up. The one under the PCM was quite rusty. Seat's out tomorrow to have a look at that one.

You're better off getting Forscan and doing the fault codes yourself....Some garages charge upwards of 75 quid just to plug in, let alone fix anything.

Are all your tyres the same size..?? This can cause issues with the ABS and T/C system too.

Lord Knobrot

[mr_miyagi]

Yes tyres are all the same size so it can't be that. I put 2 new ones on the front a month or so prior to all this going wrong and it was fine. All this started to happen after driving over some massive potholes that I couldn't avoid because of all the surrounding traffic. All I could see in the mirror was Scania about 6 foot behind me. The van was bouncing.

I'm thinking of getting Forscan for Android. I know you can't use it to change anything but at least I could read the codes. Otherwise it means buying a laptop.

I went to one local garage and asked if he could read the codes. He said it was £100 just to take the unit out of the box and then I would probably need an open check book. If I could only afford £500 then I would only get £500 worth of work and it may or may not fix the problem. I drove away and he got £0000.00

[tranmx2]

All this started to happen after driving over some massive potholes.
Likely.

The XLWB 350 ESP light has come on 3 times.
1st. Going up an incline of about 20 degrees onto the main road which was at about 5 degrees.
Wheel speed and and steering angle (yaw).
Turning right onto the main road - it is likely the weight of the vehicle was on the R right going up the slope and turning R likely caused there to be different wheel speeds and weight shift pressure - re' the wheels, the steering was also to the right. There was no wheel spin. The ESP light came on and stayed on for several mins, no power reduction, vehicle and engine stopped on restart of the engine and vehicle moved forward the ESP light did not come on.
About a year later going a bit too quick around a slight R corner. Could feel the lurch to the left and back move over a bit. ESP light on. no power reduction, stopped vehicle and engine, on restart of the engine and vehicle moved forward the ESP light did not come on.
This year vehicle stopped to turn sharp R, the road was a bit uneven. Just after turning and accelerating slightly up the slight incline the ESP light came on before the turn was complete - = power loss, got to an open area (3mins) stopped vehicle and engine, on restart of engine and vehicle moved forward the ESP light did not come on.
There is another place where the vehicle needs to stop where there is a sharp R turn and this time the road is very uneven and the vehicle must go up a slope - the vehicle is across two or three slopes - the ESP light does not come on.

The ABS releases pressure on the brake(s). There are wheel rotation sensors on each wheel. The ESP applies pressure to the brake(s). The ESP uses the ABS sensors and the steering wheel angle (yaw).

When turning sharply R or L there shall be a difference in the wheel rotation speed front and back.

Some years ago a farmer with a new fangled tractor could not turn in the yard. A sharpish turn and it and its engine stopped. He had to wait 5 mins and turn the steering back a bit before he could move again.

[mr_miyagi]

Can the Traction control be turned off completely in the PCM, deleted so to speak, but keep the ABS and hill start assist?

[gt_addict]

Sorry if this has been covered. Quite a bit to read and I skimmed it all.

Have you checked all the pad warning sensors and their wiring? I had my rear pad sensor keep telling me it was on the limit when it wasn’t. Turned out the sub loom on the van harness had gotten damaged somehow. It was the part the pad sensor plugged into.

Worth a check.

[mr_miyagi]

Yeah I've managed to find that one. The wire connector on the end of the loom wires where the fornt brake pad wear sensor wire plugs in. Where they plug together on the side of the strut. The wire had broke off the pin right where it goes into the connector. I hadn't spotted it when I was fitting the new pads. It must've been badly corroded but was still in there, probably hanging on for dear life by just one strand. Trouble is it's broke right at the back of the pin on the loom side of the connector not the pad side. At least I've found it.