glow plug code

[ESchwab]

I have a '98 E300 with 137,000 miles on it. Last night I got a check engine light, Engine Electronics. The car starts alright (there is no rough start), but after it starts the glow plug light comes on as well as the check engine light. I went to Auto zone and they got a "Code PO380 indicates a fault in the Glow Plug/Heater electrical circuit 'A' for a predetermined period of time" and recommended "replace glow plug[s]."

I haven't had time to check the glow plugs with an ohm meter. My question is, can I drive the car for a while before I tend to this? I am concerned that the glow plug light comes back on and stays on after I start the car and while it is running.

Also, is there anything besides bad glow plugs that can cause this?

I have owned the car for more than 9 years and changed the glow plugs once myself. I know what's involved; the intake manifold is a bear.

[Diesel911]

If the Engine starts OK your glow plug light issue will not effect or damage anything that I have read of.

Besides ohming the Glow Plugs check the Strip Fuse screws to see if they are tight and the Strip Fues itself for cracks.

[ESchwab]

Diesel, Thanks for your help. I have not been able to locate the strip fuse.

[ESchwab]

I used google in an attempt to find the strip fuse location and ran across this thread on a Sprinter forum. Several comments recommend ignoring glow plug issues and use of block heaters or just grinding to get the truck started when glow plugs go bad, because there are so many problems in removing the old glow plugs.

Glow Plugs - Discussion on Topix

Comment #15 was interesting. It was from billy blue balls of South Carolina. He said he uses a quarter inch drive socket to remove them and has no problems as long as he uses patience and WD40 to prepare for removal. He had done many glow plug jobs over a 10 year period. I used a quarter inch drive socket for 5 of my glow plugs when I changed mine a few years ago and had no problem. I had problems with the removal of the #1 plug, using a 3 eights inch 12 mm socket. It is larger and I think the problem was that it binds against wall of the hole the glow plug sits in.

This is a bit off topic, but interesting and close enough to topic to post.

[Diesel911]

Originally Posted by ESchwab

Diesel, Thanks for your help. I have not been able to locate the strip fuse.

There is a Plactic Cover on top of the Glow Plug Relay. Remove that and look at it and you should see the Strip Fuse.

If there is no strip fuse as in the picture you likely have a Glow Plug Relay that has a circuit breaker (look for a reset button).
I don't believe they used the relay with the Circuit Breaker for very many model years but I am no expert.

[babymog]

If it starts rough, it is not killing the engine but it isn't particularly good for it as the lash in many components will experience more wear from the rapidly accelerating/decelerating crank etc. as it misfires and runs. You will also be washing lubrication from cylinder walls in cylinders not firing, and pollute the oil with extra raw fuel.

WD-40 has not in my experience been useful as a penetrating oil, Kroil, PB-Blaster, and Liquid-Wrench have worked better and many here have preferences also including home-brew, I don't think you'll hear many experienced mechanics recommending WD-40 for much more than starting fluid. However, soaking is a good start. Note though that the problem with OM606 glowplugs isn't as much the threads, as the carbon on the glowplug further down in the hole (which will grow as it starts without that cylinder) causing them to be hard to extract.

[ESchwab]

I located my multi-meter (Craftsman $30 model) last night and checked the glow plugs this afternoon. I think I have one bad one. I got no reading for one glow plug. The others are .8 or.9 ohms. I have had no rough starts. I think that is because our night-time lows have been unusually high for the last couple of months. Two nights ago, when the temperature got down to 65 degrees, I felt one jerk or twitch of the motor on the first start-up. I haven't seen any black smoke, but I have been checking through my left door rear view mirror.

Diesel, My glow plug relay is different from the one in your picture. Mine is in sealed plastic. I don't think you can get into it without breaking or cutting the plastic. I still have not found the strip fuse. I don't think I need to at this point.

Mog, I used PB-Blaster the when I changed the glow plugs three or four years ago. I didn't remember that until I read your post.

The thing that bothered me this time is all of the darn lights. I don't think I had that many the last time, but my memory is not as good as it used to be.

I will change the glow plugs within a couple of weeks when there is a string of nice days in the forecast and report back. Thanks for all the help and comments.

[ESchwab]

I thank everyone for your help and want to report back to you. My car is a '98 e300.

I'm old and the car still ran, so I put off the repair until good weather and the need to pass inspection (the check engine light was on). I changed the glow plugs today. Five were uneventful and probably didn't need to be changed. They came out like spark plugs as I had used anti-seize stuff on them the last time I changed them. The sixth one (cylinder no. 1) was a problem.

I knew from the others when resistance was from carbon build-up. I then used a generous shot of PB Blaster and turned it back and for a number of until I tried to unscrew it further. Then more blaster and repeating the back and forth movement. After about a half hour, the glow plug came out. Then I used the reamer three or four times until I didn't get much carbon, and then put the new glow plug in.

I used a Snap-On socket that Len Sokoloff had recommended. The number is FSMS12 (six point) socket which I bought on-line from Snap-On for about $20. It worked very well, and I recommend it.

Reaming is very important. I didn't do a very good job on the no. 1 glow plug last time, because the hole is not very accessible due to obstructions. That was a mistake and is the likely the reason this one failed. I bought my reamer from Peach or Pelican parts several years ago, and it works well.