After finding his wiring diagram and this: CAL EMISSIONS: The 175 Amp Fuse feeds the Glow Plug Controller at M8. And there are two voltages from the Glow Plug Controller (OUTPUTS) that are INPUTS to the Engine Control Module (ECM) 1. Glow Plug Relay Control 505 Circuit Number 2. Glow Plug Signal 506 Circuit Number. Basically can somebody please take time out to photo there glow plug relay wiring, mainly the wiring to the right if standing in front of your truck. I think the issue is the wire with the black connector and blue sleeve to be honest. I'm in UK where there is hardly any Duramax's let alone LB7's so really stuck. Most grateful for your help guys.
![[DIAGRAM] 2003 Duramax Glow Plug Relay Wiring Diagram](https://ww2.justanswer.com/uploads/JFN1/2009-12-29_005344_1177270.gif "[DIAGRAM] 2003 Duramax Glow Plug Relay Wiring Diagram")
![[DIAGRAM] 2003 Duramax Glow Plug Relay Diagram](https://ww2.justanswer.com/uploads/KALAMYKID/2010-04-03_040450_LOCATION.jpg "[DIAGRAM] 2003 Duramax Glow Plug Relay Diagram")
![[DIAGRAM] 2003 Duramax Glow Plug Relay Diagram](https://lh6.googleusercontent.com/proxy/ueEaUZc_DTj79GukFnYvgbRiNpntToFk5lfAYus7ewu7lfnp99lfCGpNBPOc9sveKlctLLccPOuVPsp3ir38omYHJrtnQ4696-m5Twj6HmufQiWUrf6-YzSLmg=s0-d "[DIAGRAM] 2003 Duramax Glow Plug Relay Diagram")
![[DIAGRAM] 2003 Duramax Glow Plug Relay Diagram](https://lh5.googleusercontent.com/proxy/_F3d4BxaHrpmAgtGhhOO00YZn5K-GF15UhfjRPMp2MUo7A-hwDpaX7qjpoHnDyeiDcIVV3Pt4RCC29BUiaDMrzAsOdTlbHHuYrKCN-Q=s0-d "[DIAGRAM] 2003 Duramax Glow Plug Relay Diagram")
![[DIAGRAM] 2003 Duramax Glow Plug Relay Diagram](https://static5.cargurus.com/images/site/2017/03/31/14/15/pic-8278669962591991104-1600x1200.jpeg "[DIAGRAM] 2003 Duramax Glow Plug Relay Diagram")
![[DIAGRAM] 2003 Duramax Glow Plug Relay Diagram](http://schematron.org/image/lb7-wiring-harness-diagram-11.jpg "[DIAGRAM] 2003 Duramax Glow Plug Relay Diagram")
![[DIAGRAM] 2003 Duramax Glow Plug Relay Diagram](https://i1.wp.com/www.dieselbombers.com/attachments/ford-powerstroke-99-03-7-3l/23803d1330539781-glow-plug-relay-issue-2002f_exc-wiring.jpg "[DIAGRAM] 2003 Duramax Glow Plug Relay Diagram")
![[DIAGRAM] 2003 Duramax Glow Plug Relay Diagram](https://ww2.justanswer.com/uploads/therock500/2011-01-18_193719_glow_plug_relay_lb7.gif "[DIAGRAM] 2003 Duramax Glow Plug Relay Diagram")
![[DIAGRAM] 2003 Duramax Glow Plug Relay Diagram](https://ww2.justanswer.com/uploads/DT/dt69nova/2013-05-10_174549_pic.jpg "[DIAGRAM] 2003 Duramax Glow Plug Relay Diagram")
Subject:07057 -- SPECIAL COVERAGE ADJUSTMENT - ENGINE GLOW PLUGModels:2002-04 Chevrolet Silverado 2002-04 GMC Sierra Equipped with 6.6L Diesel V8 (RPO LB7 - VIN 1) Engine; and California Emissions (YF5/NE1), or Clean Fuel Emissions (VCL) Condition Some customers of 2002-04 model year Chevrolet Silverado; and GMC Sierra trucks, equipped with a 6.6L diesel V8 (LB7) engine, and California.. On my 2004 GMC 4500 w/ 6.6 duramax, the pre-heat light stays light for only about 1 second even on cold days and starts very hard. I had the glow plug controller replaced but the problem remains. Any. read more