Sunday, 2 August 2015

E60: Glow plugs + control-module - time to sort this.

I mentioned the glow plugs in this post, but have had no change in the error codes coming up for all 6. These are the last remaining fault codes that have not been ironed out since February so I thought I'd get into it in more detail now I have DIS at my disposal, which finally threw up an error for the glow plug control-module [though it wouldn't say for sure], so it's almost certain this is the fault. I read a lot of people mentioning the 'relay' on forums, but this is referring to the same part.

The control-modue is about £75 on eBay for an OEM part made by Beru, which isn't too bad. The inlet-manifold will have to come off again so I am tempted to replace all 6 glow plugs at the same time just to make sure. I do, after all, have a M57NTU2 cylinder-head lying around with 6 nearly new plugs in so it won't cost anything and seems to be a no brainer, though I am terrified of one of the current plugs will break and get stuck in my good engine.

Diagnosis:
The original scan with Autocom CDP+ only showed errors for all six glow plugs [codes 4212, 4222, 4232, 4242, 4252, 4262]. All of them were intermittent and had failed at the same times, 31 out of 40 starts. I got INPA running, which is BMW only software and read the correct DDE version 5.x instead of the 6.x forced on me by Autocom and showed correct values for the injectors, yet it just showed the same errors for all 6 glow plugs.
When I eventually got DIS up and running it threw up a fault for the glow plug control-module itself [Glow control B1362_D5BSDGSG], but with no fault-code and even after running pre-heating tests on the glow plug system [battery float-charger came in handy here] it still could not say the control-module was
definitely faulty. Instead it suggested a 'break in all lines to heater-plugs', which is seriously unlikely and after checking them in May there was no sign of this at all; and a failure in the supply of voltage at Terminal 30. Terminal 30 it turns out just means constant battery power and I tested this at the control-module socket with a solid 12v, so it would seem beyond all logical doubt that the module itself is failing intermittently somehow.

Cause:
As for how the control-module could have failed is open to debate, as it was only removed from the old engine for a short time before being fitted to the new one, not moved around and stored. Its location, right under the coolant return hose from the head means water could have spilled over the control-module at some points during the swirl-flap repair and the constant 12v supply made the module live whenever the battery was connected. In fact, as I was in such a rush to get the head back off and find the oil leak [here] I ended up draining the coolant from the return hose first, rather than fully draining the coolant from the radiator. This allowed water/coolant to run down the right side of the engine and over the starter-motor, EGR-solenoid, glow-plug controller and main wiring junction-box, which by any account was a bad thing to do. Yet, had this shorted the live wire of the module or individual plugs to ground then it would only render them inoperable temporarily and not cause damage to the units themselves. If water had got inside the sealed module or caused some sort of overload, then that would have been pretty final and I can't see how the module would work at all after that.
Both the glow plugs and control-module are the same part number throughout the entire E60 and LCI range. The design was revised for the control-module in 2005 and this is the only part available now [12217801201] and replaces the old design [12217788327]. This is largely irrelevant anyway, as both my original and 2004 replacement engine share the old part.
It could simply be the sooty condition of the new engine when I first fitted it, too much entering the inlet, or just the age of the plugs that caused my original module to work harder than it's used to and start to fail. Either way I will replace it in due course and hope it clears the 6 glow plug errors, as iy has for most people on the forums.

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