bulldogmack42 Posted February 19, 2016 Share Posted February 19, 2016 So about 3 weeks to a month ago I started getting a intermittent check engine light, but did not have a miss or loss of power, over the last couple of weeks truck seems to miss a little when idle and the light would come on after truck starts moving and stay on, the flash code is 8-4 Which if I am correct is eup #4 so I pulled it, checked wires for cut, broken, and rotted and replaced eup with new one, now engine runs the same and I still have check engine light so I'm at a loss as of what to do next. I have not had code entered into ecm yet but dont think that would cause light Quote Link to comment Share on other sites More sharing options...
Dirtymilkman Posted February 19, 2016 Share Posted February 19, 2016 Check your harness where it is plugged into the vmac box on the motor. I had a few pins get corroded over the years and do the same. Quote Link to comment Share on other sites More sharing options...
bulldogmack42 Posted February 19, 2016 Author Share Posted February 19, 2016 Are you referring to the engine ecm? Quote Link to comment Share on other sites More sharing options...
Dirtymilkman Posted February 19, 2016 Share Posted February 19, 2016 Yes sir Quote Link to comment Share on other sites More sharing options...
bulldogmack42 Posted February 19, 2016 Author Share Posted February 19, 2016 Checked the pins and all is clean and dry, no corrosion and all looks good. Quote Link to comment Share on other sites More sharing options...
bulldogmack42 Posted February 21, 2016 Author Share Posted February 21, 2016 I still can't find an answer for my check engine light, I have checked everything I know and see nothing, any and all help is greatly appreciated Quote Link to comment Share on other sites More sharing options...
wheeler73 Posted February 21, 2016 Share Posted February 21, 2016 You will need to ohm out the wires from the eecu to the unit pump. Most likely if there is a wiring issue it will be the ground as the unit pumps are ground controlled and 1,2,&3 share power and 4,5&6 share power. Also could be a defective eecu as I have had 2 with this issue in the last month. You will need to check the code to see if it is the same one or another one that could be having an issue. Quote Link to comment Share on other sites More sharing options...
TRH Posted March 5, 2016 Share Posted March 5, 2016 Check new code. Get the cal code programmed if it's on the same cylinder and check the wiring, especially visually across the back of the head where people like to leave the fucking clamp off the harness. Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
bulldogmack42 Posted March 5, 2016 Author Share Posted March 5, 2016 Just to update, I found the cause for my 8-4 code and it was in the wiring harness behind the oil filters, as TRH said "where people like to leave the f*#!;*# clamps off" 3 wires were rubbed nearly in to and grounded on the block. I for the life of me do not understand why people can't finish what they start, I mean come on people those clamps are there for a reason and not for looks...thanks to everybody who helped and guided me this is a great site with a lot of knowledgeable people who enjoy helping Quote Link to comment Share on other sites More sharing options...
theakerstwo Posted March 5, 2016 Share Posted March 5, 2016 That clamp being left off is just like guys adjusting their or some one elses clutch and leaving the dust cover off.Laszy Quote glenn akers Link to comment Share on other sites More sharing options...
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