Is Glow Plug Replacement the Answer? CEL Codes '99 E300, ADVICE Please !
 

Ok. Just bought a 99 E300 Diesel. Had it checked out by inspection service mechanics, came back great. Drove for about 100 miles, and BAM !

P0380
Glow Plug/Heater CKT A Malfunction

and

P1369
Manufacturer Controlled Ignition System or Misfire

Is this a definite indication that I need to replace my glow plugs? Does anybody know of something else cheaper/less labour extensive that I can try before replacing the glow plugs?
Is there any other diagnostic tool you know of that will tell me which plug(s) are spent?

Any responses or insight are encouraged and appreciated.
thanks guys.

-Matt

RE: Is Glow Plug Replacement the Answer? CEL Codes '99 E300, ADVICE Please !
 

:(

RE: Is Glow Plug Replacement the Answer? CEL Codes '99 E300, ADVICE Please !
 

Would anybody happen to have the part Number for this relay?
Thanks.

RE: Is Glow Plug Replacement the Answer? CEL Codes '99 E300, ADVICE Please !
 

before you go out and purchase a relay, either you, or your mechanic should check the glow plugs. If one or more need replacement, changing the relay is not going to help the situation. Good luck

RE: Is Glow Plug Replacement the Answer? CEL Codes '99 E300, ADVICE Please !
 

Don't buy parts unless you know their bad! A cheap multi meter will check glow plugs and if it is puting power to them. If your up to it just ask for directions, and there are many good owners here willing to help

RE: Is Glow Plug Replacement the Answer? CEL Codes '99 E300, ADVICE Please !
 

Thanks for the responses. I completely understand where you guys are coming from. However, I'm from the Auto Repair School of Thought that suggests " A glow plug relay is one of the most important relays on the car, and it never hurts to have a backup if I do happen to be wrong on my guess.

I've always done my own routine (and not so routine) maintenance on my cars, but have never worked on a diesel before.
Is there any way to check the glow plugs with a volt meter, without pulling the intake manifold off?
I'm not opposed to pulling the intake manifold off, but if I'm down there checking the glow plugs, I will be damn sure to have 6 plugs on hand, so I won't have to pull the manifold off anytime in the near future.

Thanks again for the replies. Look forward to getting to know some of you benz-heads better, as this is my first benz, but definitely not my last.

;)

RE: Is Glow Plug Replacement the Answer? CEL Codes '99 E300, ADVICE Please !
 

The glow plugs can be 90-98% checked just by pulling off the wire to them and taking a OHM reading from the block to the center post on the glow plug. If your OHM meter shows no reading the plug is diffently bad. The glow plug must have resistance so when 12v is applied they heat up like a toaster. 6 to 15 ohms is proper for my diesel and should be close for yours. Others can give exact spec's for your year. Second when you first turn your key on there should be 12v powerto the glow plugs," NOTE THIS IS A TIMED SUPPLIED POWER. Around 30 seconds the power turns off. So you may have to turn the key off and back on to check each wire to double check if no power was their. My 87 has a fuse strip that can go if no power to the glow plugs. Just do it in little steps. Power to the relay / plugs / resistance at the plugs. A true check is pull the plugs and ground them and see if they glow red hot, but wouldn't due before other checks were done