Traction control

Recently I noticed that when turning right at slow speed, I get chatter from the control box and the brakes go hard, sometimes losing them altogether. But if I switch off the engine, everything resets and it's normal again. Is there a problem with the sensor or could it be something more serious?

Hi - is it a freelander 1 or freelander 2? What year is it? What engine? Those are key facts others will need to diagnose the car. It might be a teltale that yor viscous coupling is getting tight and needs replacing, assuming its a FL1.

It's Freelander 1, 1999, 2 litre diesel, Lhd. It's only when I turn right and hit a bump not left.

Frankly I can't see how there's a problem there if the action is at the front right wheel

I'm not sure what control box you're referring too, but if it's affecting the brakes, presumably it the ABS modulator you're talking about (does it have ABS?). If it is the ABS modulator making the noise, are you getting any lights on the dashboard that accompany the noise?
It is possible that it's a wheel speed sensor or even the ABS ring is broken.

More information is needed really.

Yes. It must be the ABS modulator (behind the right headlight with brake lines coming out). The first time it happened was about 6 months ago. I was turning out of a side road and hit a pothole. The modulator went crazy, buzzing continuously. It felt that the brake pedal had broken so just cruised to a stop. I switched off the engine but the buzzing continued. Luckily a mechanic nearby just disconnected it. I had normal brakes then on but when it was reconnected everything was normal until I turned into a rough track and the problem came back, just not so bad as before.

I had thought it was something to do with the wheel speed sensor as the tc light comes on, but didn't want to tinker around.

The ABS ECU is obviously thinking the wheels are losing traction when they're not. So I'd check the wheel sensors and reluctor rings.

Its strange that the TC does not kick back out. I will get the TC cut in on my '99 diesel when I'm on the river bed or (very infrequently) potholed roads, but it kicks back out immediately.

When it kicks in and stay is, does the TC light stay illuminated or go out and the pump/modulator continues?

The TC light is controlled by the ABS ECU - so if the light stays lit, the ECU is getting 'messages' from the sensor to say the wheel has still lost traction. If the light goes out, but the pump carries on, then the pump is doing that all by itself.

Thanks for the feedback. The times it's happened, it doesn't kick back. Only if I turn off the engine, then it resets.
First I'm going to change the sensor and at the same time check the ring. This means that the drive shaft has to come out, yes?

Thinking about it, if this only happens on rough terrain then it must be the sensor! I have no problems when the 4 wheel drive kicks in even over rocks!

I believe that people often have to use lots of coercion and drilling to get an old sensor out!

I believe that you can look, or maybe feel, through the hole after the sensor is removed to check on the ring.

The drive shaft will obviously have to be removed and presumably split to fit a new ring.

The ring can crack due to rust underneath it pushing on it.

I don't understand how a faulty ring/sensor would work normally (ie you're driving along and the TC is not cutting in), and it can detect the wheel speed increase (ie you go over a pot hole and the wheel loses grip) - but not then work once the wheel has gained grip again. Confusing. There again, something is obviously not working properly!

Not sure why a sensor would be reset by turning the ignition off, as it is not supplied power. The pump and ABS ECU would be reset though. Maybe it has a different tolerance between switching on and off and there is a problem with the sensor?

According to the Haynes manual, " The action of the solenoid valves and return pump creates pulses in the hydraulic circuit. When the ABS is functioning, these pulses can be felt through the brake pedal" This is what I get, especially when turning.

Also the manual says that the wheel sensor rings are an integral part of the cv joint! Is this true?

4bi4 said:

According to the Haynes manual, " The action of the solenoid valves and return pump creates pulses in the hydraulic circuit. When the ABS is functioning, these pulses can be felt through the brake pedal" This is what I get, especially when turning.

Click to expand...

That's correct. But the ABS ECU should stop applying traction control, the moment traction is restored. I'm wondering if the ABS ECU has a fault.

4bi4 said:

Also the manual says that the wheel sensor rings are an integral part of the cv joint! Is this true?

Click to expand...

That's not strictly true, as the rings are a light press fit on the outer edge of the CV joint. The rings are available separately, so can be pressed on, once the old one is removed, and the joint register is cleaned.

I changed the drive shaft and the problem has gone. It must have been the ring.