Weird Glow light issues - PeachParts Mercedes-Benz Forum

bgkast · #1 04-02-2007, 01:31 PM

Ever since I changed my starter yesterday my glow plug light has been doing strange things. First it would not come on, so I wiggled the sensor on the block and it started working. Then this morning I was glowing and had to run back inside, so I removed the keys from the car and the glow plug light stayed on.

When I got back in the car and glowed again the light did not come on, and has not come on since. The car still starts fine, but I have not had a chance to verify that the plugs are getting power (though I suspect they are). I replaced the glow plug relay with a good used one about two weeks ago and it had been working fine. I am using the under dash silver type relay with pencil type plugs.

I did accidentally get a short for a second when I was doing the starter when the positive battery lead wondered back over to the battery when I was working...could that have fried something?

Thank you.

rrgrassi · #2 04-02-2007, 02:11 PM

The errant short could have fried something. I have the same type issue with a check engine light on the Altima.

Test the relay again and makes sure it is ok. Also check for any semi burned/burned wires and connections.

bgkast · #3 04-02-2007, 08:16 PM

Well something is very wrong because I went out to my car after work and the battery is flat a$$ dead.

Check my theory: The GP relay stuck on causing the GP light and glow plugs to stay glowing even when the key was removed draining the battery. Would the strip fuse blow in this scenario? Would my Glow Plugs be toast if this is what happened?

barry123400 · #4 04-02-2007, 11:11 PM

Hopefully just a discharged battery. Your replacement relay is probably marginal and sticking.

bgkast · #5 04-03-2007, 12:09 AM

The battery is on the charger, but the car had to stay at work. Whoever said you can not jump these cars is correct...I only could get a few weak cranks using jumper cables.

I think it is just throwing a tantrum because I brought it a baby sister home today.

hey_allen · #6 04-03-2007, 03:41 AM

The only reason I can think of that you couldn't jump start would be that you have too much current draw for your cables.

When I was having glow plug problems, it was that my glow plug controller/relay would stay on for 3 minutes, no matter what the light said it was doing. When I tried to crank with it doing that, I would have very slow cranking, even with an almost freshly charged battery.

Once I fixed the relay (in my case, it was spark eroded points on the relay inside), it would turn off when I turned the ignition key to crank, and the car cranked up much more energetically. Jump starting has been no problem since then.

This issue with my controller also pointed out the fact that the controller can pull the better part of 80A, whereas the alternator only puts out somewhere around 74A at peak output. (and looking at the specs, it looks like peak alternator output is somewhere around 4k engine rpm. I drive around 1.5k...) Fixing the controller issue helped my dead battery problem as well.

I don't know how much this helps, but I suspect that your glow plug controller is staying on when it should be turning off.