Author Topic: Glow plug light on dash doesnt come on  (Read 19659 times)

Offline GOODOLWHITEBOY

  • Newbie
  • Posts: 4
Glow plug light on dash doesnt come on
« on: May 22, 2009, 10:03:18 PM »
I bought an 83 6.2L diesel from a used car lot, drove it home about 90 miles, with several stops and had no issues. It ran great, until next morning i went to start and it would not fire. After some reading as i am new to diesels, i came to believe my glow plug controller is bad. I believe the dealer had sprayed it to get it going, and thats why I had no issues. Does this sound correct? Is this why my light does not come on and thus my plugs dont heat up?

Offline Mr Diesel

  • Frequent Member
  • **
  • Posts: 325
  • Aaron
Re: Glow plug light on dash doesnt come on
« Reply #1 on: May 23, 2009, 04:27:57 AM »
There are 3 main components of your glow plug system. 8 glow plugs (1 per cylinder), a relay, and a thermal controller. If your 1983 is original it uses this controller
http://www.autozone.com/autozone/catalog/oems/oemsShelf.jsp?displayName=Glow+Plug+Controller&itemId=prod60343&totalPages=[I@17deaee&currentPage=1&vehicleNValue=&sortType=null&fromType=oem&navValue=16201750&parentId=cat30070&fromString=search&filterByKeyWord=gpc2&categoryNValue=16299999&categoryDisplayName=Ignition+(Tune+Up)&_requestid=351884

The relay is also readily available at any parts store. That is located on the fender inside the engine compartment (passenger side I think).

You should first test each glow plug individually. Disconnect the wiring harness at each glow plug and using a test light connected to the positive battery terminal touch the glow plug spade terminal. If the test light comes on that glow plug is good. If not, it is not working. Replace your glow plugs with ACDelco 60g type ONLY. Most other kinds can overheat and swell, getting stuck inside the cylinder head.

Next test your relay. Locate it and use a jumper wire from the positive battery terminal to the small connector on the relay. Use a test light or a voltmeter touching the terminal leading to the glow plugs to see if power is traveling through the relay when you activate it. This is easier with 2 people.

Last component is the thermal controller itself. These fail every several years, so I do not recommend skimping by buying a used one. I don't remember which terminals to test on it, but if you test the plugs and the relay first it should tell you if the controller is bad.

EDIT: If you do need a new thermal controller make sure you get the right one. In 1984 they went to a different style controller. All military humvees and 1982-83 trucks use the old style controller. Don't bother trying to retrofit a newer style on. Just get the right one so it is plug and play. If for some reason yours does not look like the picture in the link above, someone has already retrofitted it, in which case just get the newer style which is more square. Both mount at the rear of the engine on the cylinder head.
« Last Edit: May 23, 2009, 04:32:18 AM by Mr Diesel »
1976 C20 Crewcab, 6.2L/SM465
1982 K30 Crewcab , 427TD/TH400
1983 C30, 6.2L/TH400
1983 K30 Crewcab 454/700R4
1986 K10 350/400. 1989 K30 cab/chassis 454/SM465

Offline VileZambonie

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 18980
Re: Glow plug light on dash doesnt come on
« Reply #2 on: May 23, 2009, 10:21:41 AM »
Glow Plug - No Wait Lamp, Starting Difficulty
Notes
 

GMC NUMBER: 89-T-28
 
GROUP: 6D - Engine Electrical
 
DATE: February, 1989
 
CORPORATENUMBER: 836414
SUBJECT: COLD START OR HOT RESTART DIFFICULTY WITHOUT GLOW PLUG WAIT LAMP
 
MODELS: 1983-89 C/K/R/V/G AND P MODELS WITH 6.2L DIESEL ENGINES (VIN CODE C,J)
Some customer comments have been received regarding no cold start capability or hot restart difficulty during mid-range engine temperature. Cases of no cold start may be the result of the glow plug inhibit switch not operating correctly. Reference Corporate Service Bulletin #866001 for glow plug system diagnosis.* Meanwhile, cases of poor hot/warm engine startup may be the result of starting system degradation, and may require glow plug assistance for engine starting. Replacement of the existing glow plug inhibit switch with a new service switch without a coolant temperature sensor (listed below) win provide glow plug assistance upon engine start, regardless of engine coolant temperatures. This feature will not reduce glow plug life.

New Part Numbers

1983-87 LH6*/LL4 - 23504005 1988-89 LL4(Only) - 23504006* 1988-89 LH6 not equipped with glow plug inhibit switch
Service Switch Without Sensor Installation

1. Disconnect batteries.
 
2. Replacement service switch can be installed in exact location of the inhibit switch with a socket wrench. (Do not use open end wrench.) Tighten to 19-27 N-m (13-20 lbs./ft). Replace any lost coolant.
 
3. Connect glow plug inhibit switch connector assembly to service switch.
 
4. Reconnect batteries.
 
IMPORTANT: Glow plug operation (Wait Lamp) will be observed more frequently on the hot engine restarts with the installation of this service switch.
 

Parts are currently available from GMSPO.

* Chevrolet Bulletin #88-49, GMC Truck Bulletin88-T-39 and GM of Canada #88-662-100
 

Use applicable labor operation number and time.
 
 
,                           ___ 
                         /  _ _ _\_
              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline zieg85

  • Global Moderator
  • Senior Member
  • ****
  • Posts: 7543
    • 73-87 GM squarebody extended cab and conversions up to 91 R/V series
Re: Glow plug light on dash doesnt come on
« Reply #3 on: May 23, 2009, 11:27:02 AM »
Great info here, let me be the 1st. to welcome you to the site.
Carl 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
https://www.facebook.com/groups/248658382003506/

Offline GOODOLWHITEBOY

  • Newbie
  • Posts: 4
Re: Glow plug light on dash doesnt come on
« Reply #4 on: May 23, 2009, 03:28:14 PM »
Thanks for the info and the welcome, I come from the 4 banger Jeep world. So this diesel thing will be a good learning experience. Along with knowledge here I should be alright. Have my dad coming out tomorrow to give an extra set of hands. Problem with living in the sticks takes awhile for help to come.

Offline AdrianR

  • Newbie
  • Posts: 33
  • Big Blue Beastie - '85 Suburban K10, 6.2 diesel
Re: Glow plug light on dash doesnt come on
« Reply #5 on: May 23, 2009, 04:45:24 PM »
Of course, there are those that say, "to heck with the electronics. I'll make the decisions". They go and fit a pushbutton to the glower relay for full manual control of the plugs.

If you go this route, you MUST replace ALL 8 plugs with Delco 60G as they are self-limiting and will not burn out, swell up or otherwise cause trouble if overheated.

I have a manual pushbutton on my '85 Suburban 6.2. Even in the coldest, lowest winter temps here in Toronto she fired right up - just needed  more glow time than the factory controller gives you.
Chevy lover
1985 Suburban K10 Silverado diesel

Offline VileZambonie

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 18980
Re: Glow plug light on dash doesnt come on
« Reply #6 on: May 23, 2009, 04:48:43 PM »
Are you using the push button to control the relay? I hope you're not running high current through the switch directly.
,                           ___ 
                         /  _ _ _\_
              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10