D4d hilux brake light came on when pressing brake pedal

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Posts: 1
Joined: Tue Oct 28, 2014 8:07 am
Town: Vereeniging
Vehicle: Hilux 4.0 V6
Real Name: Charles

Can anyone provide some advice on what the problem is. If I or apply brakes while driving the pedal feels normal but suddenly gets hard to press and the handbrake light come on. Check brake fluid level which is correct. Install new brake pads and shoes and bleed brake system but with no effect. If traveling at higher speed it seems not to happen. Only driving in town at lower speeds. I've also noticed at a robot if brake pedal is applied the light will come on but not always. Can the brake booster be faulty. It is a 2006 model with 340000km on the clock.
Any advice will be appreciated.
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Mud Dog
Posts: 29845
Joined: Tue Apr 29, 2008 2:18 am
Town: East London
Vehicle: '90 SFA Hilux DC 4X4, Full OME, 110mm lift. Brospeed branch, 50mm ss freeflow exhaust. 30 x 9.5 Discoverer S/T's on Viper mags. L/R tank. (AWOL) '98 LTD 2.4 SFA, dual battery system. Dobinson suspension, LR tanks, 31" BF mud's.
Real Name: Andy
Club VHF Licence: HC103

Hi and welcome Charles. :thumbup:

If the pedal feels hard or gets harder as you describe, that normally points to a booster problem of some kind. Check your vacuum line to the booster for any damage / perishing where you could have a vacuum leak as well as the connections at the booster and the manifold.

Ideally the booster should hold and retain enough vacuum for 2 or 3 brake applications after switching off the engine. If you depress the brake pedal with the engine running, the pedal should feel normal and while keeping it depressed turn off the engine. If the pedal pushes back and feels 'harder' after turning off the engine, you have a vacuum leak.

This leak could be on the vacuum pipe, it's connections or inside the booster itself (diaphragm). Another possible leak could be a pin-hole in the booster body from rust or other damage.
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Posts: 10627
Joined: Thu May 17, 2007 9:12 pm
Town: Langebaan
Vehicle: 2.7 Hilux 4x4 DC
Real Name: Pieter
Club VHF Licence: X27

I never worked on a D4D before, but I know some turbo diesels have a vacuum pump and do not draw vacuum from the manifold like petrol engines. If your D4D has a vacuum pump I will also check it out for a possible cause. Start with the vacuum lines like Andy suggested, it is the cheapest part to start with.
Only Dead Fish Go With The Flow!
1999 Hilux 2.7i 4x4 Raider DC with 3.4 Prado V6. Rear diff-lock, Bull Bar and rock sliders, 31" Cooper ST Maxx, Snorkel, Alu-Canopy, VHF Motorolla radio, West Coast Rust, Mikem Suspension, Ball Joint Spacers in front and Mikem extended shackles at the rear, 25watt LED Spots
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