Glow Plug Not Turning Off? Engine Won't Start.

Hello everyone,

'On my Golf III (1Z), the glow plug light has suddenly stopped turning off. It's constantly illuminated, not flashing. At the same time, the engine won't start. The starter motor is turning, but that's all.'

The search function repeatedly leads back to the troublesome topic of 'Relay 109'. Are there now any concrete indications that this relay can cause the described error? Do you have any other ideas?

Where can I find relay 109 in a 1995 Volkswagen Golf?

Best regards and thank you in advance.

Martha.

As far as I know, if relay 109 is broken, then no power reaches the control unit, and the lamp will no longer light up at all.

Hello everyone,

I first bypassed the contact points of relay 109. Lo and behold, the preheating lamp went out, and the engine started.

I then confidently bought a new 109. But, imagine that! The problem isn't with the 109 itself. The relay is not being triggered correctly. Terminal 30 is internally connected within the relay between the working contacts and the coil. The other contact of the coil is directly connected to ground by the control unit (at least, that's how it is in a 1995 A4 TDI; unfortunately, I don't have a wiring diagram for the Golf III, but I assume it's the same there).

I suppose we have to assume that the control unit's output relay is defective, or what?

I will automate the bridging of the electrical contacts with a relay (which switches on with the ignition), essentially creating a 'bypass'.

Regards,
Martha.

Read error codes!
Everything else is just fishing in murky waters!

As far as I can tell from the error, you may be missing a ground connection on or inside the control unit.

Bertil wrote:

As the error appears to me, you may be missing a ground connection at or inside the control unit.

Hopefully, it's just a broken wire in the control circuit of the 109 -> check the wiring between the relay and the engine control unit, or simply run a new wire.