CAN Bus Glow Plug: Installation & Troubleshooting

Hello diesel mechanics,


Could it be that vehicles with a CAN bus system no longer have a dedicated wire for the preheating light, and that the information is instead transmitted via the bus?
Specifically, it was (or is ) a Passat AWX model from the year 2001 with the engine control unit 038 906 019ER (Bosch 0 281 010 704).
Okay, I'm going to start installing the engine in my VW bus now, and while I was looking at the wiring diagram, I noticed something about the glow plug. Or did I misread something?
'Does anyone happen to have the pinout diagram for the control unit (STG) in 'Bosch style'? I find it more organized than the wiring diagrams from VW.'

Regards,

Maciek.

hello Maciek,

For vehicles with a CAN bus system, you indeed only have 2 wires connected to the pre-glow light.
When and for how long the light illuminates is purely a software matter and depends only on the programming. The duration of the light can be the same as the preheating time, or it can be different.

I doubt that you can simply get away with using a single control unit, i.e., a small part of the original CAN bus system, because VW, like all other manufacturers, assigns individual tasks of the overall system to control units that have nothing to do with the specific function, simply because they are located closer physically.

So: good luck!

Please provide the German text you would like me to translate into English.

Hello,

The two lines that you are referring to are the CAN bus .
As I understand it, the signal for the indicator light will be transmitted via the bus.
It's not that bad because I can also see on the glow relay whether it's glowing or not.
The problem is that when I do that, the light's function as a fault indicator is lost, and I also get the afterglow indication. I need to figure out a way to make the light only activate when the engine isn't running yet.
The engine is being operated without the original Passat instrument cluster with the integrated WFS, because such modern technology looks strange in a van.
Okay, if you had a Bosch pinout diagram for the control unit (STG), that would already be helpful.

Regards,

Maciek.

Certainly, no CAN bus wiring goes to the lamp itself; instead, there's a ground wire and a positive wire that are controlled by the control unit (I'm not sure which one at the moment).

The various buses connected the control units to each other.