answers about my modified glow plug modules

I posted about the modified glow plug modules I make a while back. I get emails that ask the same questions, so here's the scoop.

They are modified to allow external fuses instead of the hard-wired internal fuses, which are bypassed. When a GP fuses to ground or has too high a draw, the external fuse for that particular GP is blown, not the entire module. This cuts costs ( 10 cents instead of $87+) AND shows you which GP is having a problem without having to run a diagnostic or set up a makeshift wiring device to test each individual plug.

This probably voids any warranty on effected systems, I don't know.

They take about 15 minutes to install unless you can contort and do it without taking out the battery tray.

They cost a little under $100, and I need the old module as a core, or a deposit for the cost of a used module.

I use all new wire, fuse block and fuses. The module is a used OEM GP module/relay.

They work with 2002-2006 2.7l engines (OM612 and OM647).

Sorry about such a blatant ad, I wanted to be subtle before but had to field the same questions, especially about price, all the time.

surlyoldbill said:

I posted about the modified glow plug modules I make a while back. I get emails that ask the same questions, so here's the scoop.

They are modified to allow external fuses instead of the hard-wired internal fuses, which are bypassed. When a GP fuses to ground or has too high a draw, the external fuse for that particular GP is blown, not the entire module. This cuts costs ( 10 cents instead of $87+) AND shows you which GP is having a problem without having to run a diagnostic or set up a makeshift wiring device to test each individual plug.

This probably voids any warranty on effected systems, I don't know.

They take about 15 minutes to install unless you can contort and do it without taking out the battery tray.

They cost a little under $100, and I need the old module as a core, or a deposit for the cost of a used module.

I use all new wire, fuse block and fuses. The module is a used OEM GP module/relay.

They work with 2002-2006 2.7l engines (OM612 and OM647).

Sorry about such a blatant ad, I wanted to be subtle before but had to field the same questions, especially about price, all the time.

Click to expand...

Looks like a good idea, if the glow plug fries, how does it kill a battery or alternator, let alone the glow plug module? This would prevent all the above I would think? It could maybe be hidden under the battery tray to avoid warranty issues being denied etc.

The glow plugs only assist in starting. Once the motor has been running a bit, they are irrelevant. The module is already under the battery, and putting the fuses further under the tray would negate the ease of changing the fuses if needed. The module/relay bundles all 5 fuses together inside, and they are not replacable or repairable. If you blow one fuse, you have a dash warning light and a DTC stored, and must replace the module just because of one fuse. $110 vs. 10 cents.

I understand they only assist in starting, but many people here have had shorted glow plugs and then bad glow plug relay, fry batteries, and alternators, so they can cause damage, but I know they are only for starting as intended purpose.


Hiding the fuses was for warranty Dept to not deny a warranty due to a MOD!!! that was all, but the function of your creation is very good!!

kkanuck said:

...
if the glow plug fries, how does it kill a battery or alternator, let alone the glow plug module?
...

Click to expand...

I will give you the Sprinter glow plug module basic world as I see it, so take it for what it's worth.

If a glow plug shorts or for some other reason draws too much current, then there is a fuse built into the glow plug module which will open and isolate that glow plug position. Along with the fuse is a comparator circuit which monitors the output and is used to set the DTC diagnostic trouble code. If a glow plug fails open, the fuse remains intact, but the comparator circuit sees the lack of output to that position and should also set a DTC.

I don't see how a shorted glow plug which blows a fuse is able to drain the battery on it's own because it is isolated.

Within the glow plug module there is a single pole mechanical relay which is closed to provide power to the glow plugs through the individual built-in fuses, or in Bill's case, through his added less expensive external ones. I believe that when the glow plug module is responsible for draining a battery, the mechanical relay either sticks closed due to some mechanical problem, or the contacts are burned to the point that they stick together and don't open. I feel the fused (stuck together) contact scenario can be the result of age and operations, or possibly it may be accelerated by glow plugs shorting and drawing current spikes which burns the contacts. Either way, the current on the contacts is fairly high anyway.

Apparently the glow plug wiring is sized such that it doesn't burn the wires. That may be a result of good design or poor conduction through the failing (failed?) relay contacts. When the relay remains closed after it has been de-energized, it is the good glow plugs that provide the current draw and resulting load on the battery which drains it down.

Anyway, that's what I think is going on. I don't think it would take much during Bill's modification to add an LED indicator to show that power has not been removed from the glow plugs by the mechanical relay after the engine is running. Of course given the location of the module/added fuses, it would take opening the hood to see it. Still it would be a pretty easy check. vic

Please forgive my limited knowledge of this site and my mechanical background.

This sounds like a winning program to me as I am having GP issues presently and would like to use this system on my 06 sprinter. Where is the info to put this system together for normal (knuckle head) people like myself.

YOU GUYS ARE GREAT!

thanks
Reid

You can get one through surlyoldbill, info is at the top of the thread, he needs your old core, and it is little under $100.00 for the useful mod!

I will eventually do this also ..... but for now my glowplugs aren't needed

Fall bump....You do nice work there Bill

Scott_Mc said:

Fall bump....

Click to expand...

Sounds like what happens to me after excessive celebration.

Bill does do a nice looking job with that modification. It's much better than buying OEM module after OEM module as glow plugs fail. vic


Edit: There is now a second generation new design solid state glow plug module available from MB which is reported to isolate a bad glow plug (or harness ground) and not blow an internal fuse. This indicates to me that if you purchase the new design OEM glow plug module it should not be affected by subsequent glow plug failures. It should have long(er) life.

One thread is here:
https://sprinter-source.com/forums/showthread.php?p=197919#post197919

Aqua Puttana said:

Sounds like what happens to me after excessive celebration.

Bill does do a nice looking job with that modification. It's much better than buying OEM module after OEM module as glow plugs fail. vic

Click to expand...

Funny you should say that...I was in your state...town of Rhinecliff on Saturday eve doing just that!

I got all my excessive celebration over with in college, and in a few short years after that.
What's booze like these days, anyway? Any different?

surlyoldbill said:

I got all my excessive celebration over with in college, and in a few short years after that.
What's booze like these days, anyway? Any different?

Click to expand...

It must be different, It takes me 3 days to get rid of a hangover instead of 1 when I was in college

Is there a guide anywhere on how to do this modification?

TIA

romi7519 said:

Is there a guide anywhere on how to do this modification?

TIA

Click to expand...

TIA,
I used the search tool in the blue bar above.

I used "glow plug module".

I scanned down and quickly realized (as any noob would) that clearly the 24th hit down on the list was probably what you were looking for.

2003 glow plug module dissected
https://sprinter-source.com/forums/showthread.php?t=6935&highlight=glow+plug+module

Sorry. I'm giving you a bit of ribbing. The search function works OK, but even better after you've spent way too many hours reading things on this forum (like I have ) so then you have half an idea of what threads to check.

Let us know if that thread isn't what you had in mind. Hope this does some good. vic

P.S. - If you're not fairly familiar with detailed soldering it very well may be worth buying the modified module. The conversion is a bit of a pain. Not impossible, but not a piece of cake either.

Bill ,
please contact me in regards to purchasing one of your modified Glow Plug Moduals.
I sent a private message several days back but dont know if you received it. I am a new member to the fourm and am still learning how to navigate the site. george3345

Aqua Puttana said:

TIA,
I used the search tool in the blue bar above.

I used "glow plug module".

I scanned down and quickly realized (as any noob would) that clearly the 24th hit down on the list was probably what you were looking for.

2003 glow plug module dissected
https://sprinter-source.com/forums/showthread.php?t=6935&highlight=glow+plug+module

Sorry. I'm giving you a bit of ribbing. The search function works OK, but even better after you've spent way too many hours reading things on this forum (like I have ) so then you have half an idea of what threads to check.

Let us know if that thread isn't what you had in mind. Hope this does some good. vic

P.S. - If you're not fairly familiar with detailed soldering it very well may be worth buying the modified module. The conversion is a bit of a pain. Not impossible, but not a piece of cake either.

Click to expand...

I have read that thread but there is no info on how to go about doing this mod. I am a noob and I need a bit more guidance than others hence my previous post. Thanks anyway.

Please don't take this the wrong way. I just went back and reviewed the thread I suggested for you. I really think all the information needed is there. If you're unable to apply what's there and do the modification you probably are over your head for this one. Buying a modified module may be the best course of action for you.

The modification makes a bunch of sense if you plan to own your Sprinter for many years. The cost averages out for long ownership. It will pay for itself if even just one (more) glow plug fails during your ownership. Good luck. vic

romi7519 said:

I have read that thread but there is no info on how to go about doing this mod. I am a noob and I need a bit more guidance than others hence my previous post. Thanks anyway.

Click to expand...

Not intending to hijack the thread but I need some info and may need to purchase this part. If your module blows a fuse and needs replacing does that trigger a check engine light on the dash? I just purchased a 2004 and am fairly new to the Sprinter world. Cold weather has revealed a cold start issue with our van. It takes well over 30-40 seconds for the GP light to turn off and even then it sounds like it's only firing on three or less cylinders at fire up. The main question is, can I just get away with changing the GPs or is the new module required if there's no dash idiot light. In other words, how does one determine if the module has blown fuses and or needs to be replaced?

Bigdaddydaveh said:

Not intending to hijack the thread but I need some info and may need to purchase this part. If your module blows a fuse and needs replacing does that trigger a check engine light on the dash? I just purchased a 2004 and am fairly new to the Sprinter world. Cold weather has revealed a cold start issue with our van. It takes well over 30-40 seconds for the GP light to turn off and even then it sounds like it's only firing on three or less cylinders at fire up. The main question is, can I just get away with changing the GPs or is the new module required if there's no dash idiot light. In other words, how does one determine if the module has blown fuses and or needs to be replaced?

Click to expand...

Sounds like you may have glowplug issues. The glowplug light should take longer to go out as temperatures get colder. A CEL won't light for glowplug problems, but the glowplug light itself may indicate problems. If it comes back on after starting and then goes out in about a minute, that means one or more glowplugs are open circuit (I have that condition). If the glowplug light comes on after starting and stays on, that means one or more glowplugs are shorted to ground. I believe aqua puttana had the case in his '04 where there was no indication at all (no guiding lights) that some glowplugs were bad. I believe he wrote extensively about his glowplug issues - search using the search tool in the blue bar above.