Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help




Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 03-11-2008, 09:15 PM
Registered User
 
Join Date: Feb 2008
Posts: 45
Glow Plug Relay Troubleshooting

I have this ongoing issue with my mysterious glow plug system on my 83 300DT. It works pretty much when I don't need it, after I get to my destination and the car is already warm. 75% of the time, when car is cold, glow light does not come on and its a hard start. 20% of the time, when it works, the beast starts right up. Although, it will always work when the engine is warm....every time. Is this an ignition/electrical issue? Could the relay be faulty sometimes? My guess is the ignition connection somewhere. I tested all the plugs many times, get good ohms 0.2. I get 12.5 volts at all three posts, even when the relay is not working. Although I get 12.5 volts at the relay, when I turn the key, no clicking at the relay. Why would it work sometimes? I ordered a used relay on its way, but something tells me I will still have this same issue. How does one test the ignition posts and connector at the relay? I suspect this is my issue.

Any help is appreciated.
Reply With Quote
  #2  
Old 03-11-2008, 09:43 PM
Registered User
 
Join Date: May 2002
Location: USA
Posts: 1,114
You might check out my post on cleaning the contacts in the relay. It worked for me.
Reply With Quote
  #3  
Old 03-11-2008, 09:58 PM
Registered User
 
Join Date: Sep 2004
Posts: 8,548
Quote:
Originally Posted by legasea View Post
How does one test the ignition posts and connector at the relay? I suspect this is my issue.
On the smaller (four pin) connector on the top of the timer, check for battery voltage at terminal #1 when the switch is in the "run" position. If you don't have that, the relay isn't going to close.
Reply With Quote
  #4  
Old 03-11-2008, 10:11 PM
Diesel911's Avatar
Registered User
 
Join Date: Sep 2007
Location: Long Beach,CA
Posts: 24,864
Quote:
Originally Posted by tangofox007 View Post
On the smaller (four pin) connector on the top of the timer, check for battery voltage at terminal #1 when the switch is in the "run" position. If you don't have that, the relay isn't going to close.

And have someone slowly jiggle the key and see if the voltage fluctuates.
Just in case you have not seen it the Diesel Gaint site has a setp by step pictorial oh how to check the GPs and relay.
__________________
84 300D, 82 Volvo 244Gl Diesel
Reply With Quote
  #5  
Old 03-11-2008, 10:21 PM
Registered User
 
Join Date: Feb 2008
Posts: 45
Quote:
Originally Posted by neumann View Post
You might check out my post on cleaning the contacts in the relay. It worked for me.
Are you talking about the contacts on the exterior or did you have to open it up? My relay looks brand new, no corrosion on the exterior. I will try testing the ignition with a multimeter on #1 post as the other posted also suggested. If you have the link to your original post, please share, I did not see it while searching.

Thanks for the advice.
Reply With Quote
  #6  
Old 03-11-2008, 10:46 PM
83 300SD
 
Join Date: Mar 2007
Location: Shawano, WI
Posts: 691
www.dieselgiant.com has a the DIY for GP testing.

John
__________________
Certified Registered Nurse Anesthetist (CRNA)
2002 F250 powerstroke with Plantdrive WVO conversion
1983 300SD 190K miles ,sold
2006 E320 CDI
Reply With Quote
  #7  
Old 03-13-2008, 11:49 AM
Registered User
 
Join Date: May 2002
Location: USA
Posts: 1,114
The contacts are inside...you have to open it up.
Reply With Quote
  #8  
Old 03-23-2008, 09:16 AM
Registered User
 
Join Date: Feb 2008
Posts: 45
Resolved

Quote:
Originally Posted by neumann View Post
The contacts are inside...you have to open it up.
Second hand relay solved the problem. The original relay was only working 50% of the time, everything else checked out so I purchased a second hand relay and so far, its been 100%. Thanks for all the help on this, my starter also thanks you!
__________________
1983 300D Turbo
265,500 miles
Reply With Quote
  #9  
Old 03-23-2008, 12:14 PM
Registered User
 
Join Date: Nov 2004
Location: Nova Scotia, Canada.
Posts: 6,510
I would not throw the old relay out though. Someday your new one might need a part. Say the actual relay coil burnt out. (pack rat I suppose) On the otherhand if you keep it your present one will never go bad.
Reply With Quote
  #10  
Old 03-24-2008, 12:30 PM
Registered User
 
Join Date: May 2002
Location: USA
Posts: 1,114
Remove the outer case and you will see two contacts that will need to be cleaned. I do not have any pics. Maybe took 15-20 minutes for the whole process.
Reply With Quote
  #11  
Old 03-24-2008, 09:18 PM
Registered User
 
Join Date: Feb 2008
Posts: 45
Quote:
Originally Posted by neumann View Post
Remove the outer case and you will see two contacts that will need to be cleaned. I do not have any pics. Maybe took 15-20 minutes for the whole process.
I had it apart and it was clean, I still ran a piece of sandpaper in between the contacts to clean it anyway. I did notice that one of the two contacts was not making contact when closed. I thought this was by design. I did not want to start bending the contact and force it down if it was not supposed to be. Either way, for $20 I got a used one that has been 100%. If I get bored and have no other MB projects (unlikely now that I am converting to WVO), I will mess with the contacts and reinstall. I will try to bend the one so they are both touching.
__________________
1983 300D Turbo
265,500 miles
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 04:41 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page