Glow Plug Relay? - PeachParts Mercedes-Benz Forum

sasquatchgeoff · #1 11-01-2014, 08:32 PM

602.911

This problem is an "all of a sudden" issue. No warning, no starting issues whatever prior, and solid, well timed, good running engine. The only variable that has changed is a lot of wet weather and cooler temps.

Here's rough synopsis:

Get in car, cabin light comes on, put key in ignitition, turn key to mid-point, normal idiot lights come on, continue turning key to right to start glow plugs - all (I mean all) power in the vehicle shuts off. Wait a minute or so, and I can repeat the same process with every detail the same. The consistency is the glow plug light does not come on, nor does the starter engage.

No orange glow plug light - at all. When the key is at that position, all power in car dies temporarily, and if left in that position, permanently - but I did not test that permanence.

Checked battery, battery is good (fully charged by alternator) as well as grounding for entire system.

Glow Plug Relay?

Ignition Switch?

markg612 · #2 11-01-2014, 10:04 PM

So if i read your post correctly--first that ignition switch has 4 positions.

OFF
POS 1---accessories on
POS-2---run
START--momentary on, engages starter.

So you're saying if you move from OFF, to 1 to 2 and it all goes black going from 1 to 2 and on to start?

Off the cuff, I'd ring out the ignition switch first, its easily accessible after you remove the knee bolster and trim below the dash.

Let me grab my ETM for the 201 and see if there's a fuse/fusible link in that circuit, it's been a while since I had 201s and 124s, (circuit layout is nearly identical) but I seem to remember some type of current protection for the high draw of Position 2.

markg612 · #3 11-01-2014, 10:13 PM

Check fuse 7, 9 and 10--

Fuse 10 is a 25A
Fuse 9 is an 8A
Fuse 7 is a 16A

mach4 · #4 11-01-2014, 10:42 PM

Corroded battery cables??? Get a terminal cleaner, clean the terminals and try again.

sasquatchgeoff · #5 11-01-2014, 11:22 PM

Quote:

Originally Posted by markg612

So if i read your post correctly--first that ignition switch has 4 positions.

OFF
POS 1---accessories on
POS-2---run
START--momentary on, engages starter.

So you're saying if you move from OFF, to 1 to 2 and it all goes black going from 1 to 2 and on to start?

Going from 1 to 2 kills all power in the vehicle and as a result the momentary on/starter engagement cannot occur.

Oddly, I can let it sit in "off" position for a few minutes and do the process all over again. Somehow the power magically comes back for position "1" (and the dome light, fuel gauge, etc) which clues me to a thermal issue - or thermal protection at least.

Will check fuses in daylight tomorrow and report back.

Thanks,
Geoff

ROLLGUY · #6 11-02-2014, 12:17 AM

Could be a ground strap connection (or lack thereof) as well, but my vote goes to a bad ignition switch....Rich

psaboic · #7 11-02-2014, 12:24 AM

Pull the power plug to the glow plug relay and see if that helps or not.

markg612 · #8 11-02-2014, 10:12 AM

Quote:

Originally Posted by sasquatchgeoff

Going from 1 to 2 kills all power in the vehicle and as a result the momentary on/starter engagement cannot occur.

Oddly, I can let it sit in "off" position for a few minutes and do the process all over again. Somehow the power magically comes back for position "1" (and the dome light, fuel gauge, etc) which clues me to a thermal issue - or thermal protection at least.

Will check fuses in daylight tomorrow and report back.

Thanks,
Geoff

Hokay, I've pouring over the ETM and fuse 9/10 are your dogs if they're blown. They power circuit 15, which is RUN, and if 15 isn't powered, nothing in the run position will work.

This is the link to the ETM on Startekinfo.

http://www.startekinfo.com/StarTek/outside/11832/Resources/201Create/PDF/01002.pdf

If none of this shakes out, I've not gone there yet, but the damnable K1 Overvoltage Relay seems to participate in more issues than I can understand. There is also a fuse on top of some of the new versions.

sasquatchgeoff · #9 11-02-2014, 02:26 PM

Excellent. Thanks so much for the info. I will also check the K1 once I locate it.

Geoff

sasquatchgeoff · #10 11-03-2014, 06:34 PM

Quote:

Originally Posted by psaboic

Pull the power plug to the glow plug relay and see if that helps or not.

Checked all fuses - OK. Pulled power plug on glow plug relay then tested ignition power - power stays on, i.e. when glow plug relay is out of the circuit, the system is OK. Bad glow plug relay?

Thinking further, for some reason the glow plug relay has malfunctioned. Could a weak or dead glow plug be the cause?

Can the K1 overvoltage relay still be suspect? I ask because when the GP relay is in the circuit and the ignition switch is in "start/run" - all power in the vehicle turns off, as if a breaker is thrown due to a ground fault. The power is killed ONLY when the switch is turned to the "start/run" position. After a few minutes, if the switch has been returned to the "off" position, the power comes back magically.

Any ideas appreciated.

Buying a second GP relay now....

markg612 · #11 11-03-2014, 08:12 PM

It's almost as though the relay is dead short to ground-did you pull the plug off that goes to the glow plugs and try it and leave the control plug connected?

Also, I'd almost circle back to the battery terminals and ensure they are clean and making a good current carrying contact vs just enough contact to show good voltage??

PS, it looks like neither Worldpac or the other supplier who's name is not known don't stock the glow controller anymore. MB of South Atlanta has 2 different part numbers 0015454426 & 0035451032 $198.40 and $176 respectively (these guys are one of the few MB oem resellers that offers real discounts AND sell online)

sasquatchgeoff · #12 11-03-2014, 09:39 PM

Battery terminals are good. That was my first suspicion. I have not checked the glowp!ug leads off with the power connector on. Next step. If that results in the same shutdown behavior, I should have a pretty good idea the GP relay has failed. The car does have approx 340k on it. That's a lot of starts. The same glow plugs are in use since I have had the car (190k). I don't think they are original, but there has never been a single problem.

A certain parts supply house in AZ has the relay for $95. I am going to get a junkyard special though. The part # is 003 545 8832

markg612 · #13 11-03-2014, 10:55 PM

This is really piquing my curiosity.

There is a strap fuse in the glow controller for over current, i.e., a short to ground glow plug, of which I've never seen, always the other way the burnout open, and the glow light doesn't come on telling you a plug is out.

One would think if there is a direct short to ground, like it's behaving, the strap fuse would blow or something would melt!

sasquatchgeoff · #14 11-04-2014, 02:20 PM

OK, just tried the following:

1. Disconnected glow plug lead (5-pin connector) from the glow plug relay.
2. Reattached the 4-pin connector to glow plug relay which is the point at which the glow plug relay is contained within the ignition switch circuit.
3. Turned the ignition switch to "start/run" and power remains - all idiot lights come on, fuel gauge works, dome light stays on. No glow plug idiot light.

In other words, the 5-pin glow plug connector has a pin that is shorting to ground? Could this be a glow plug that is fried and for some reason the glow plug is shorting to the block?

I am getting my multimeter out to test each lead. Where is this strap fuse? Is the arrow pointing to it?

barry12345 · #15 11-04-2014, 10:06 PM

Yes that has to be the fuse.