How common is it for W210 glow controllers to fail? - PeachParts Mercedes-Benz Forum

shertex · #1 07-04-2016, 03:21 PM

I have an extra brand new glow plug controller for my 98 E300....came with an assortment of parts that I purchased from someone who had sold his E300. Trying to figure out if I should try to sell it or hang on to it in case mine goes out.

whunter · #2 07-04-2016, 07:41 PM

Hold onto it, as a spare and diagnostic tool.

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jay_bob · #3 07-04-2016, 08:08 PM

From what I have read on the forum the most common failure with these is the data connection to the ECU. It is a two pin connector with small gauge wires.
Tjts1 had this problem.

They do not use CAN for the signaling.
One wire is the glow start/stop signal from the ECU, the other is a pulsed signal giving feedback to the ECU.
These controllers are not smart enough to know exactly which glow plug has failed, only whether there is a failure in a pair (1 or 2, 3 or 4, etc).

tjts1 · #4 07-04-2016, 08:34 PM

Yes it's true, I had this happen to me but my car is a 97 and almost all the engine electronics changed every single year between 95-98. So I'm not really sure if it's a 97 specific problem or not. If you have access to a spare GP relay for your car hang on to it.

Jeremy5848 · #5 07-04-2016, 08:56 PM

Following tjts1's comment, I can testify my very-early 1996 E300D uses the same pre-glow relay as my 1995 (W124) version of this same car. This part is 015-545-30-32 and has no connections to the CAN bus because Mercedes introduced it gradually during the 1996 model number and my car was thankfully too early. By 1998 there was definitely a completely different relay in use; the question then is where did 1997 fall during this change?

tjts1 · #6 07-04-2016, 11:23 PM

Here's my spare 97 relay, maybe its the same as 98. I initially thought the whole relay was bad and replaced it but in fact it was just the stupid 3 pin plug on the bottom.

Look how thin those pins are, they're like needles. The plug has a few MM of movement when its plugged in so I can see why it makes for bad contact. Who was the genius who thought this up?

If I remember correctly only 2 of the 3 pins are used. I took apart the relay and soldered wires into it that run to the outside of the housing with proper connectors to the car's wiring harness. It was the only reliable solution. Pardon the masking tape, it was supposed to be temporary.

Jeremy5848 · #7 07-04-2016, 11:33 PM

Good, thanks. Your 1997 is the later "smart" version. Mercedes must have made the change during the 1996 model year or at the beginning of 1997. The early 1996 cars have a preglow relay just like that in older models going at least back to the last W123 diesels.

Murkybenz · #8 07-05-2016, 04:27 AM

This appears to be the worst fault they can suffer
Glow plug light 320 CDI W210 - Page 2 - Mercedes-Benz Owners' Forums

shertex · #9 07-05-2016, 08:05 AM

Tjts1, mine is exactly the same as years, including the details of the small print, EXCEPT for the MB brand and part number. It looks like whoever in Hungary makes the part sells it through channels other than MB.