CEL for Glow Plugs - Upgraded controller, all glow plugs test fine

TROLL

2007 Winnebago View 23H
Any other guesses as to why I would have an intermittent CEL for glow plugs on my 06 T1N Sprinter?

Trouble codes are:
PO671 - cylinder 1 glow plug circuit/open
PO672 - cylinder 2 glow plug circuit/open
PO380 - glow plug / heater circuit A

I believe I've had other CELs for other cylinders at times as well.

The engine is an OE reman with 65k miles on it so the glow plugs are low mileage and when removed and tested with a multimeter they all show less than 1 ohm resistance.
I did not test my old glow plug controller, but I just went ahead and replaced it with the newer version.
My CEL remains. It doesn't affect the way the vehicle drives and doesn't seem to affect cold starts either, but why do I have this insistent CEL? I've put up with it so far but would prefer to save the CEL for other "real" issues I need to know about.
 

BrennWagon

He’s just this guy, you know?
If everything checks out individually, the engine to chassis ground would be a good point to check. Was the ground strap original to the van or the engine? A new ground strap is cheap and can solve a plethora of faults, especially in high amp circuits
 

Midwestdrifter

Engineer In Residence
A plug that tests good cold may go open circuit when it gets up to temp. The fuse test works great. You can also test on the bench with 12v direct from a battery. No more than 30 seconds, and stop when the plug starts glowing.
 

TROLL

2007 Winnebago View 23H
You know, the ground cable from battery to firewall was modified by the previous owner to add a cutoff switch and it did have a bad connection once before. I was on the road so I just tightened it which fixed the issue and continued on. I will take it off fully to inspect, clean up, and fix if needed. Cant hurt!

Hmm... where is the engine to chassis ground? I mean, I removed the engine so I'm sure I disconnected it along the way and its just already going fuzzy on me.
 
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TROLL

2007 Winnebago View 23H
Can you helpful people explain how to do the fused lead test?
The glow plugs are installed back in the vehicle now -- would I be unplugging the glow plugs 1 by 1, connecting a fused jumper harness with a 25-30A fuse (and reasonably thick wire gauge) between the glow plug and the glow plug connector on the harness?
Does this need to be done right at key on?

If someone can explain or link me to an already written explanation I'd appreciate it! I did a little searching and didn't come up with directions for dummies on this one to make sure I get valuable test results!
 

outbound

06/2500/140
Any other guesses as to why I would have an intermittent CEL for glow plugs on my 06 T1N Sprinter?

Trouble codes are:
PO671 - cylinder 1 glow plug circuit/open
PO672 - cylinder 2 glow plug circuit/open
PO380 - glow plug / heater circuit A

I believe I've had other CELs for other cylinders at times as well.

....

i was having those same codes, turned out to be the engine wiring harness, which had chafed thru
and shorting in wet conditions, where it's strapped-to the steel mount pad just below the fuel filter - see that pic with the GND strap.

the chafing was not readily apparent until i'd removed the old harness.
so to check that spot, ya need to unstrap it, lift it up and look beneath where it makes contact.
if it's chafed thru you'll see it.

and it's definitely worth checking out.
:2cents:
 

TROLL

2007 Winnebago View 23H
Dang, just had it all apart and would have been easy to check but it’s back together now. Appreciate the tip, I will look into that when I can.
 

Nautamaran

2004 140” HRC 2500 (Crewed)
The “Fused lead” glow plug test canbe performed at the controller 6-pin plug.
Pins 1..5 connect to cylinders 5..1, Pin 6 is not used.
Feed Bat(+) into a #10 awg wire via a 20 amp fuse and touch the harness connector’s pins one at a time, hold each for about 10 seconds.

If the fuse blows you have a short to ground, (and you’ll need another 20 amp fuse, so try to test the good GPs first! ;-)
Watch for a small spark as you remove the wire, which indicates that the glow plug was drawing power and is okay.
No spark indicates either that the GP has failed open or that you have a wiring harness issue.

-dave
 
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TROLL

2007 Winnebago View 23H
Just did the fused jumper test in the video linked below — got the “big spark” on cylinder number 2, all the others seemed fine.
Good reason to go ahead and replace this one glow plug even if it had less than 1 ohm resistance when I tested it out of the vehicle?
Any other testing I should try first?

https://youtu.be/K5B5ZM4Usgo
 

TROLL

2007 Winnebago View 23H
Ok, that’s what I figured but just wanted to make sure my test and results met your quality standards to meet that conclusion since I’m sort of electrically slow :).

What is the reason that the resistance test would show under 1 ohm like all the others, but the plug would immediately short in this test? That’s the part where I get lost.
 

220629

Well-known member
Ok, that’s what I figured but just wanted to make sure my test and results met your quality standards to meet that conclusion since I’m sort of electrically slow :).

What is the reason that the resistance test would show under 1 ohm like all the others, but the plug would immediately short in this test? That’s the part where I get lost.
Failure modes can vary. The GP includes a heating and a control winding. The control winding can make a bad GP display a "correct" ohm reading. If you were testing at the GP module plug, you could have a harness issue. #2 position is easy to test directly on the GP.

:cheers: vic
 

TROLL

2007 Winnebago View 23H
Ok thank you. Hopefully you checked out the video I linked — I tested all glow plugs directly at the top of the glow plugs so any faults should point directly to the plugs themselves.
I will try to pick up a replacement for cylinder 2 today if they have it in stock and see if that fixes one or more of my trouble codes. About to hit the road again so fingers crossed the dealer stocks them (not waiting any longer to get back on the road, been stuck in place for 2 months rebuilding this engine).
 

Midwestdrifter

Engineer In Residence
Most multimeters cannot accurately measure resistances below about 10 ohms. So the one ohm you measured could actually have been a quarter of a ohm or 1.5 ohms. There is a very big difference in how much current one polls versus the other.
 

Nautamaran

2004 140” HRC 2500 (Crewed)
What Vic said...
I’m just chiming in to compliment you on your videography. Nice job! (holding your hand flat in frame can help solve auto-focus issues)

Wishing you well finding a local GP supply.
They’re not uncommon, so you’ve got a good chance...

-dave
 

Heatnairguy

New member
I have found the glow plugs at Advance Auto parts and though I didn’t check Dodge or MB I’d be surprised if either one were as low in price.


Sent from my iPhone using Tapatalk
 

TROLL

2007 Winnebago View 23H
Interesting, do you know the manufacturer?

I found an OE glow plug in stock at the nearest MB Sprinter dealer and planned to go grab it tomorrow. It’s about $25 — more than Europarts SD but for just one and being able to get it quickly I’m at peace with it :).
 

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