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ML 320 CDI W164 Code P0670 - Glow Plug Control Module Circuit

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by flymech1, Nov 8, 2013.

  1. flymech1

    flymech1 Member

    Likes Received:
    Oct 16, 2013
    Newcastle Upon Tyne
    Your Mercedes:
    ML320 CDI W164
    Hola Señors and Señorita's,

    My ML320 CDI engine had a leaking injector for quite some time... I decided to ignorantly chug around for a while (a long while) until recently, as I thought it was getting worse. Reason I thought this was because the engine was struggling to start in a morning after sitting for a while. I thought that due to the lack of full compression in a cylinder AND a suspected glow plug or 2 out it was enough to tip it over the edge.

    I bought an injector puller tool, a stretch bolt and a copper injector seal and sorted it out (after spending hours cleaning the Black Death carbon off) and the next morning... It wouldn't start! It had been a cold night and morning so I boiled a kettle and carefully poured hot water over the front end of the block to help warm it. That was enough to get it going. Checked on OBDII codes and I had P0670 - Glow Plug Control Module Circuit....

    Next chance I got I checked the applicable fuse then popped the caps on the glow plugs and ran a resistance check on all the plug tops to GND. All seemed ok as around the 1 ohm mark. (I assume they're all ok and not all dead!). Next thing to check was the relay (AKA Control Module) and as not much can be gleaned from the outside I decided to get Mr Stanley knife to help me look inside... Straight away I seen the problem... A tell tale burn mark on the plastic inside and blown fuse wire on the motherboard... I've just resoldered 15amp fuse wire in the blown position and tested it... All seems fine, although the engine was warm so there may not have been much current passing through the control box lines... It's another cold night here so I'm sure the plugs will need some juice in the morning. I'll be ready with my OBDII Code Reader and multimeter and will report back. If anyone's got any questions feel free to fire away... I'm no expert but I'm winning so far and I'm sure there are experts on here that can help resolve what I can't (or tell me how stupid I am!)



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