BKD Converted Caddy - Why are my brake lights staying on ?

[D1cky]

Hopefully someone can assist me with the following fault codes.

My 2007 Caddy (originally a 2.0 SDI), it recently had a 2.0 TDI BKD engine fitted out of a 2004 Golf GT TDI.

The van/engine runs fine and boosts as it should.

The glowplug light constantly flashes.

And it has the stored faults below.


●Brake Lights

DTC Code: P0571

The brake lights stay on when ignition turned on, they illuminate without the brake pedal being depressed.

The brake light switch has been replaced for a new Febi one.
All feeds/wires to the brake light switch have been tested and they are fine.

They have 12v feeds where they should and the ground terminal has good continuity.


●Fuel Pump

DTC Code: P1541

It will not prime/run when the ignition is turned on.

The fuel pump will prime/run when a jumper wire that provides 12v power is connected to Fuel Pump Relay Terminal 2 (87).



All feeds/wires (1-->5) (30-85-86-87) to the fuel pump relay have been tested and they are fine.
They have 12v feeds where they should and the ground terminal has good continuity.


Could this be due to fusebox/glowplug wires being connected incorrectly ?

The Fuel Pump Relay has me stumped as I've tried new relays with no success.


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[D1cky]

Fuel Pump issue resolved. Dodgy connection.
The brake light and flashing glowplug light continues.


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[Doc]

There may be a problem with the power to the brake pedal switch. If I remember correctly, the lights stay on constantly when the switch circuit fuse blows, it's a fail safe feature.

[D1cky]

There may be a problem with the power to the brake pedal switch. If I remember correctly, the lights stay on constantly when the switch circuit fuse blows, it's a fail safe feature.

The fuse is fine. Strange.
I checked it. I was hoping it was that for an easy fix

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[Doc]

Have you checked for power at the brake pedal switch?

[D1cky]

Have you checked for power at the brake pedal switch?

All good.
I have power.
I checked wires K65, K87 to the ecu from the brake switch electrical connector for continuity.
Checked the brown one too.


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[D1cky]

Continuity Check(s).

https://youtu.be/a5mgtPABLDk?si=qHokISh2lqWszotX

Ignition Power Feed to switch.

https://youtu.be/Z-Xn7FfqsF4?si=f0bPYqKX8nMru_Wq

[D1cky]

All good.
I have power.
I checked wires K65, K87 to the ecu from the brake switch electrical connector for continuity.
Checked the brown one too.

Although no mention of a brown wire on the wiring diagrams. Odd...

https://youtu.be/LF7FjtSNmRU?si=qTh_5RsqszcCJ_Dm