Date registered: Oct 2012
Vehicle: W204 C320CDI 2009 and W639 Vito 115CDI 2006
Location: Perth, Western Australia
Mentioned: 4 Post(s)
Quoted: 86 Post(s)
How to Repair/Modify Glow Plug Controller Module
I now have a 2008 W164 ML320CDI in the family fleet.
My daughter has just bought it and good old Dad looks after it for her. She bought it from a dealer so it had a three month warranty thank goodness. The GP controller failed and it was replaced under warranty. The cost down under for the part is an exorbitant $800 or thereabouts.
I did some research and found 99% of the time these things fail due to the control module not getting the 12V power supply. I asked the repairer for the old module as it was going in the bin. The controller is a common part A6421532079 and used in many different diesel Mercedes and Chrysler models from about 2005.
I dismantled the thing and discovered it's very simple to fix permanently and more robustly than it's original condition. It's the same part number as my W204 C320CDI so I took mine off and plugged in the repaired and modified W164 item and it works perfectly. About an hours work to save $800 of your hard earned and to give you a more reliable controller.
I find this sort of thing extremely annoying. The dealers are doing a roaring trade selling replacements at $800 and perfectly good controllers are ending up in landfill. I'm not sure if it's planned obsolescence or what.
The flimsy cheap aluminum wires used to connect the 12V terminal to the PCB are a joke.
I'm in the process of making a "How to" video to show anyone interested how to make the repair/modification. Even if yours is still working it's probably worth doing this modification before it fails and lets you down at an inconvenient time. If you live in a very cold climate I'd be doing this modification now.
Once the video is done I'll post a link here.
I'm riding for you #52, my dear son Cameron 1985-2009
2009 W204 C320CDI C Class sedan with Quaife LSD
2006 W639 115CDI Vito LWB Van for hauling motorcycles
2008 W164 ML320CDI Edition 10 (daughter's but I look after it)
2011 VW Polo 6R Hatch
2008 Honda CBR600RR race/track motorcycle
2010 Suzuki GSXR750 race/track motorcycle
2011 KTM 530 EXC Enduro motorcycle