I've been "ignoring" this little issue for a short while now, but when my wife asked me about it I thought it was time to put the electrical gurus' to work.

I've noticed recently that my SGII will come on for 3-5 seconds and then go off for no apparent reason. This has happened a few times, apparently at random, mostly after the truck has been sitting for a few hours. I don't know how long this has been going on; no telling really. I do know that on a normal cold start of the truck that unless I manually turn the SGII on it doesn't come on immediately until the alternator comes up to full voltage (14+) and/or the glowplugs go off. It never has. Nothing out of the ordinary is going on starting wise, or electrically, I just noticed that this was happening and I'd like to know what's making that circuit energize randomly.

 

My first suspect is your SGII. You could check the OBDII either by pin checking it, or even easier: plugging in any other reader or adapter interface... I'm going with it is your Scan Gauge going bonkers on you...

Scott

 

 

Maybe I described the "problem" wrong? The SGII is working just fine when it's active. It comes on and goes off as requested as it has for all the years I've had it, it's just that recently I've noticed it come on for a few seconds and then goes back off after it's been asleep for hours and I was wondering why.

 

Ghosts. Just accept it.

 

After thinking more about it, I think you're probably right, Scott. I was thinking something in the truck was making it come on, but since it can power on without the truck being on, I'm thinking you're probably right.

 

Try changing what turns it on and see if that fixes the issue.
Mine has the issue of being slow to turn on.

 

I keep the IPR, EOT EWT and Volt gauges running on mine and, fairly regularly, the IPR and EOT gauges will lock up. Have to turn the key off/on and it works again. For a while, it didn't work when connected into the side, so I had to use the rear port, but now the side works again. Can't get it to work right with my E450 at all. And the plastic clip broke on mine, just like every RJ plug ever. I've stopped in a couple of places but haven't found anyone to replace the clip yet. Sure is a cheap way to make these.

Another strange thing - the temp will never read 200. It'll jump from 199 to 201 and back over and over, but never displays 200.