What's causing all this?

**Dunsmorechap** · 18-07-2010,06:51 PM

Got a 2003 Passat SE 130 TDi, AWX engine. On Friday pm while driving up north, the ABS and ESP lights came on together, and within 30 seconds the glow plug light started flashing with an ENGINE WORKSHOP! warning. The cruise control also stopped working though the light will still come on/off with the switch.
Also, over the last month of so I've noticed a faint noise from around the centre console/glove box area (almost like laptop hard drive in use).

The car still drives fine, with no physical problems evident, would all this happening at the same time be something to do with the ECU or something else??

**martin1810** · 18-07-2010,07:35 PM

You need a fault code read. It's pointless guessing.

**passat 130 tdi** · 18-07-2010,08:06 PM

check the brake fluid level - and have a fault code scan done as recommended.

**Dunsmorechap** · 19-07-2010,04:44 PM

Well took it in today and it was the brake light switch that was at fault. I'd love to know why VW has the engine management light come on for a brake light switch!

**martin1810** · 19-07-2010,07:18 PM

Because one signal from the brake light switch feeds the ecu. Vital if a car is ever fitted with cruise control.

**Dunsmorechap** · 19-07-2010,08:13 PM

Right, that makes a bit of sense now.

Thanks for the replies.

**David Horn** · 21-07-2010,01:53 PM

The brake light switch is more than a dual-output switch. Because of the fly-by-wire accelerator, the computer needs an unambiguous indication of what's happening with the brakes. Hence the switch is actually a two-bit binary switch, delivering 01 in the "brakes off" situation and 10 in the opposite "brakes on".

It only takes one output to be sporadic and the computer will get implausible signals, such as "11" or "00". Hence it gets upset when it doesn't know what's going on with the brakes, and you lose ABS, and as a secondary failure, ESP.

DSG4ME · 21-07-2010,02:46 PM

It's a common fault, one way if you can ever catch it to see it's going south, is your brake lights will stay on without the pedal being depressed.

**olnmfc** · 04-10-2010,09:46 PM

Ive had the traction control light coming on 10 mins after start up. Brake lights working normally altho 1 bulb may have been inop. Checked/replaced the bulbs, ABS connections and replaced the pedal switch (for the new version with self adjusting plunger). Fitted it without touching the pedal but the traction control light still religously comes on after 10 mins driving... Any ideas????
p.s brake lights work normally as before.
pps when driving without the switch fitted got flashing glow plug, stop workshop sign, ABS, traction lights all on, but all off once refitted switch except the traction control light as mentioned after 10 mins driving..