D4 won’t start

[dwaters]

Hi all, chasing some help please. Last night I went to start my car to drive home after a meeting but the car would not start. I thought it was the brake locking it out but I could see this was working each time I pressed the brake. All the lights on the dash would light up but just no ignition. Both batteries were fine and RAC confirmed this also. I disconnected both batteries for approx 5 mins but still no luck. I ended up getting it towed home so had to manually select neutral to get it on the tow truck then back into park when it arrived home. Still won’t start. I have no idea as it has been fine all day. I have not driven off road or through any puddles. It’s a 2016 tdv6 FYI. Would love to hear your thoughts. Thanks

[DiscoJeffster]

You need to get the codes read to determine the issue

[dwaters]

I had RAC check the fault code and there were none.
No faults on dash either.

[Graeme]

The stop/start button can fail in this manner and IIRC a faulty brake light switch can also cause this.

[dwaters]

Thanks mate, the stop start seems to work as all the accessory light come on.
The brake light switch appears to be working as I can see the warning come up on the dash when I take my foot off the brake. I did also manually exercise the switch too but still not ruling it out as I think there are multiple contacts on this switch and although the one to dash seems to work, the one to the ecu may have failed.

[DiscoJeffster]

I had RAC check the fault code and there were none.
No faults on dash either.

Get it to a specialist with a more Land Rover focused diagnostic tool would be my advice.

[dwaters]

Yep that’s what I am doing. It’s on the tow truck now……]

[mowog]

Did you try the emergency start procedure?

On the lower part of the steering column right side there are 3 lines Hold the key against that and try.

I had no start and no smart key found. My KVM module had failed.

[Graeme]

I think there are multiple contacts on this switch and although the one to dash seems to work, the one to the ecu may have failed.Yes, 2 sets of contacts. One learns to carry a spare switch.

[dwaters]

Thanks for the reply and no I didn’t try that but it seems to recognise when the smart key is within range as I tried starting it without the key in range and the smart key not in range came up on the dash.
Vehicle is on its way to the specialist do I am hoping it’s an easy fix.
Possibly the brake switch?
Thanks

[mowog]

T
Vehicle is on its way to the specialist do I am hoping it’s an easy fix.
Possibly the brake switch?
Thanks

With my D4 its never been the easy option when it goes wrong. Lucky for me my LR specialist is my neighbor

[DazzaTD5]

Just off the top of my head...

*look at fuse for the ABS / dynamic control module.
*look at the continuity of the pins on the plug for the abs module.
*The fuse for the KVM may well be good, but pull the fuse, ponder life for a bit then put the fuse back in.

[Eric SDV6SE]

Sometimes you need to push the brake pedal a bit harder to get it to start. My wife is 5'8" and has trouble pressing hard enough on the brake pedal on occaision (funnily enough no issues with the go pedal) I've tested the brake switch and it's fine, seems the ecu monitors brake pressure as well to make sure before releasing for a start sequence.

[DiscoJeffster]

Sometimes you need to push the brake pedal a bit harder to get it to start. My wife is 5'8" and has trouble pressing hard enough on the brake pedal on occaision (funnily enough no issues with the go pedal) I've tested the brake switch and it's fine, seems the ecu monitors brake pressure as well to make sure before releasing for a start sequence.

Well not exactly. If you deplete the vacuum then the pedal doesn’t go low enough to properly release the brake switch. That is the issue you probably experienced. When there’s residual vacuum the pedal descends to the required point easy enough.

I had my wife experience this when I’d been in the car messing with it with the engine off. She came out and said it wouldn’t start. Hard push on the pedal and all good.