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Discussion Starter #1
Recently swapped the starter with a new one and had to rewire the starter harness as it burned up. Since I haven't been getting the glow plugs light on the dash when I turn the key. I replaced the glow plug relay, no luck. The coolant temp sensor is a couple months old. I hear the relay click and see the battery gauge jump when waiting for glow plugs. I have power to the glow plugs, 10.5v. The plugs are 2yrs old. GP fuse is good.

It was 8 degrees and the truck turned over after about 10 seconds (I am in Chicago). It blows a ton of white smoke at start up. Once warm, it starts immediately. Any thoughts on where the breakdown is here? I have no glow plug light on dash, I am not convinced that plugs are hot at start. Thanks!
 

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I can't recall for certain on the 6.5s but on my Mercedes diesels if the glow light doesn't come on it is a sign that at least one of the glow plugs is burned out. Others will chime in.
 

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The glow plug fuse only has power when the glow plugs have power.
Probe the fuse with a test light and see if you get power when you turn on the key.
 

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Discussion Starter #4
Yes, I have power at the fuse as described. Thanks!!
 

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1995 GMC Suburban
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Burnt WTS/GP dash bulb?
 

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Discussion Starter #6
Maybe a burnt bulb. Guess I should be happy with the low temp start. Thanks for your thoughts and ideas!!
 

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1995 GMC Suburban
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It is fairly easy to check the cluster.

Check the thread on changing the bulb with led on the how to somewhere in the FAQ.

Your objective is just to know how to see behind the cluster.
 

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Discussion Starter #8
Thanks for the cluster idea. I am going to go through and check the connections/grounds. May even swap out the temp sensor. If that doesn't do it, I will tackle the cluster. Thanks for pointing out FAQ availability.
 

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NOTE: These charts are specific to '95 OBD1 models but are very much applicable to '94 OBD1 models with a couple noteable exceptions.
On '94 models, the Fuel Pump Test Terminal is "G" (slot below F), not "F" as it is for '95 models.
'94 models dont have an Underhood Main Fuse/Relay Box aka "Convenience Center."





Perform

#1. OBD System Check



Anything?






#2. Glow Plug System Check
NOTE: Glow Plugs utilize 2 fuses. 20amp ignition source and 10amp fuse that simply protects the Glow Plug Lamp and PCM from an overload (short).. Be sure to check/test both.





If nothing is found.
#3. DTC 29 Glow Plug Relay Circuit Fault

 

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Discussion Starter #10
Awesome, thanks for the diagrams!! I will run through them today. I do have OBD 29 code, BTW.
 

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Discussion Starter #12
Odd thing happened...put paper clip in to check codes, Glow Plug light came on. This happened for three 3 turns of key. Took paper clip out and no GP light. Put paper clip in and then no light. I reset computer via break and gas pedal method. No change. Don't think it's burned out.
 

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Check all your fuses THOROUGHLY..

I suspect your fuel heater is malfunctioning and possibly disabling the glowplugs...
If you find a blown fuse (eng1 or eng2, ECMa or ECMb, etc) replace and take note of ambient temps. If its below 45°F, the fuel heater normally turn ON the moment the ignition is turned ON, unless it shorts out internally (circuitry) or externally wires short out at the severely deteriorated electrical grommet found at the base of the fuel heater...
Anyhow.. Try starting it again, see if the WTS (GP) lamp starts to function normally or not at all because the fuse blew again. If you find a blown fuse and blow the replacement, STOP. Disconnect the fuel heater, replace the fuse(s), and try again, couple times.
If normal GP function returns, guess I dont need to tell ya you need a new fuel heater....
 

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Discussion Starter #14
Thanks for all of the help here, an incredible knowledge source! I pulled all the fuses and checked them and pulled apart the connections and doublechecked them. Glow Plug light is working again. I still have the OBD code 29. Not sure that I am out of the woods but headed the right direction. Will keep this thread bookmarked to continue troubleshooting. Thanks again!!
 

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Presumably the 94's ignition switch is similar to the 95+ in that its got way too many contact sets so you could have intermittent issues with only certain sub systems? And in a 94 the electrical part of the switch is down at the bottom of the column under the dash so its slightly easier to change than the 95+ that is up mounted near the lock?
 
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