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Coil light on dashboard:Hi all, i have one for you... i press the brake my front left light comes on when i release it, it go's off. I turn my lights on after a few mins when driving my coil light on my dashboard flashes, turn my lights off, it go's off after couple of mins. i changed the bulb (rear brake light) ill check the bulds again. Any ideas?????????? i have read the threads not sure where to go or start advice please:*:*:*:*:*:*:*:*:*:*:*:*:*:*:*:*:*:*:*:*:*:*
 

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I did all the recommended actions but GPLF is still happening on my T4 2.5 TDI from 1998. I clear the fault code but the blinking light comes back after driving around 3-5 minutes.

In the last test today I removed the brake switch, cleared the fault and then just switched on power without starting the engine. Same result. After 4 minutes I get GPLF again. To my understanding with the switch disconnected the wiring to the brake lamps are totally disconnected from the ECU. So in my view this eliminates the brake switch and the brake lamps and cables as the cause of the problem. What remains then? Well maybe the ECU tries to check some conditions related to the (non existing) switch for the cruise control.

Next thing I will try is to get a 4 pin brake/cruise control switch. I don't have cruise control on the car but I can see that thee is a connector for the cruise control switch coming out from the harness. According to the T4 Transporter current flow diagram page 80/4 the switch is called F47 (a 4 pin switch). I get back to you when I have tried this. I had the GPLF for more than a year now...
 

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I did all the recommended actions but GPLF is still happening on my T4 2.5 TDI from 1998. I clear the fault code but the blinking light comes back after driving around 3-5 minutes.

In the last test today I removed the brake switch, cleared the fault and then just switched on power without starting the engine. Same result. After 4 minutes I get GPLF again. To my understanding with the switch disconnected the wiring to the brake lamps are totally disconnected from the ECU. So in my view this eliminates the brake switch and the brake lamps and cables as the cause of the problem. What remains then? Well maybe the ECU tries to check some conditions related to the (non existing) switch for the cruise control.

Next thing I will try is to get a 4 pin brake/cruise control switch. I don't have cruise control on the car but I can see that thee is a connector for the cruise control switch coming out from the harness. According to the T4 Transporter current flow diagram page 80/4 the switch is called F47 (a 4 pin switch). I get back to you when I have tried this. I had the GPLF for more than a year now...
I had the same problem as above with the same van. ( 1998 2.5tdi 102 ) Turns out its the throttle position sensor.
Part number 7D0721727. These are dimond encrusted gold plated units. At least I think they are as they cost £441.30 + VAT from tps.
 

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Finally the problem is solved. Previous owner fitted a 2-pin brake switch instead of the right type of 4-pin switch (which is no longer available). The 4-pin switches available today has one 4-pin connector. My T4 TDI has 2 separate 2-pin female connectors, one for the brake light which shall close when you press the brake pedal and another one for the cruise control which shall open when you press the brake pedal. I don't have a cruise control but it appears that the ECU still check that the cruise control switch at the brake pedal is there. So the solution was to buy current type of 4-pin brake & cruise control switch(called F47 in the wiring diagram) and a 4-pin connector and remove the old 2-pin connectors that were fitted in the car before.

This was a long journey...
 

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THe 4-pin switch has one pair that closes when braking. This control the brake light. The other pair opens when braking and is to my understanding used by the control unit to signal that the cruise control shall be switched off. I don't have a cruise control but still the control unit checks both for closing and breaking. If any of the signals are wrong the glow plug light starts flashing.
 

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Thanks to all contributors, my fell out when I saw yellow flashing light (usually means money, lots of) followed guide, dismantled switch and added a dab of grease to the "plunger" on the switch. Fault cleared and wallet closed!♥
 

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I'm having problems with the glow plug light tried all the above except changing the switch I've had it apart tried it throu VCDS and this is what I'm getting in pictures below.
I'm on the seat loom and have to switches blue top and white I'm thinking blue may be to do with cruise control which may be active even thou I don't have it.

Ross tech say the value should be 000 but I can't get the value even with the switch off.

Brakes off





Brakes on.

 

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Brilliant bit of info Edblue - many thanks.

We were driving into Santander to get the ferry back to Blighty when the light started flashing. Found this thread and dismantled the switch in the Port and found one of the two outer contacts eroded. Scraped it with a screwdriver and reassembled it.

Came on briefly until I pressed the brake pedal - JOB DONE! T: Just under 500 miles to Edinburgh and no more light. THANK YOU A:
 

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Hi Guys, I'm getting no brake lights? I have a 4 pin switch in which I'm getting 12v at pin 1 and pin4 when pedal pressed no 12v??
Tested with a continuity tester and it makes contact so why no voltage? The wire is purple white out put is this correct?

Many thanks
 

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I've got a slightly different problem.

Brake lights are sticking on and coil light flashing.

I've replaced the brake light switch with a new one however the lights are still sticking on.

I've connected the switch, the lights come on, i've pushed the plunger in and out but the lights stay on so i've pulled the fuse for now.

Wondering if the new switch is faulty too or if there is something else i need to check?


Any help would be appreciated.
 

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Switch is located properly and bulbs are in right.

This was an intermittent problem that developed into the brake lights being permanently on, which is why I thought it was the brake light switch that was faulty.

Could it be the ECU?
 

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So tonight i've stripped down the original 4 pin switch (which is different to internally to the one in the pic) one of the contacts was a bit fried but i cleaned it up. I then replaced the new switch with the original switch and refiited it, however the brake lights are still stuck on and the GPWL is still flashing.

I'm at a loss now.

I had a look around the other pedals and there is a plunger switch on the clutch and this also seems to be connected to another sensor/switch on the accelerator pedal, i'm assuming these are for the cruise control system, however i don't have cruise control fitted.

Has anybody got any other ideas about what could be causing the brake lights to be stuck on?
 

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So tonight i've stripped down the original 4 pin switch (which is different to internally to the one in the pic) one of the contacts was a bit fried but i cleaned it up. I then replaced the new switch with the original switch and refiited it, however the brake lights are still stuck on and the GPWL is still flashing.

I'm at a loss now.

I had a look around the other pedals and there is a plunger switch on the clutch and this also seems to be connected to another sensor/switch on the accelerator pedal, i'm assuming these are for the cruise control system, however i don't have cruise control fitted.

Has anybody got any other ideas about what could be causing the brake lights to be stuck on?
I had a polo in last week that we failed it's MOT for brake lights sticking on, it was when the side lights were on and turned out to be a poorly fitted bulb causing earth issues, replaced the bulb and sorted! Just a thought.
 

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Hi I have a 1999 2.5 litre van I have the usual symptoms flashing glow plug light and have no brake lights working way all now I've looked at my pedal and I have two switches both of which are 2 pin female connections I've tryed to strip them down but they appear not to be able to fully strip them down like in the picture I have LED bulbed rear light the fuse is fine and the symptoms appear to be intermittent as one day they work the next they don't I'm at a complete loss
 
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