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Melange of DTC codes!

Thanks Jim. Well, at least every time I see the bear, I smile.

bearshit.jpg
 
Hi guys... here's an update.

Shortly after changing the glows, I took the truck out and ran some errands.

After getting home and leaving truck in the driveway, I went out to start it up, and it threw codes everywhere (the same melange as before).

This left me thinking that I agree with Tim, it has to be a flakey power or a loose ground wire. I thought about the schematic for the glow plug circuit... it has:


  • PCM
  • Ignition switch
  • Switched power to glow plug relay through Ignition switch and ENG-1 fuse.
  • Glow plugs
I've basically replaced all active components except the PCM, which I don't think is bad. It acts more like a loose connector.

I've checked all the grounds, and checked many of the power connectors as well.

Since it was malfunctioning at the time, I decided to try and poke around with my voltmeter to see if power was getting where it should. Since I know that switched power is NOT getting to the glow plug relay, I decided to pop the fuse box in the engine bay and look at the contacts for ENG-1 fuse. As soon as I touched the voltmeter probe to the ENG-1 fuse, the glow plug relay clicked and the glows started glowing. Hmmm.

Hmm. The fuse is in there pretty loose, not tight like the others.

I took a very small jeweler's screwdriver and slipped it in-between the plastic housing and the metal connector for the fuse holder, to 'reform' the metal of the holder to force it to grip the fuse more tightly.

Noted that the fuse appeared to have some light dielectric fretting on the legs of the fuse. Rubbed off the fretting/corrosion and then re-fit the fuse.

Fuse fits in very tightly now.

Everything appears to be working, and has continued working all through the day today.

That might have been it. I'll keep monitoring it for now.

Thanks for listening. I need to check the schematics to see what else the ENG-1 fuse is hooked to.

Rob :)
 
I would do that fuse cleaning on 100% of fuses in that truck if you havn't already. Can't hurt to check your PCM harness's for coorosion also.
 
Matt,

Excellent suggestion. I just went out and spent about 30 minutes cleaning all the fuses in the engine bay fuse center. (hint: Dremel tool with wire brush works very well for this task - small enough to brush off all the corrosion without being unwieldy) Frankly, I suggest EVERYONE SHOULD DO THIS. There was a significant amount of corrosion on every single fuse in the block. I also pulled the relays for headlights, etc. They had some corrosion, but nothing like the fuses. I'll take Matt's advice and pull the PCM harness for corrosion as well. Ahh, time and corruption takes its toll on our trucks as well as our own bodies, eh?

Rob :)
 
Turbine Doc said:
Di-electric grease after cleaning terminals probably would not hurt either
Click to expand...

Hi Tim,

Good suggestion too. I almost did it, but hesitated, as there is probably also an equal amount of corrosion on the fuse sockets, but I don't see any easy way to clean those. The best I could think of was to insert and remove the fuse several times, which I did. We're only 1/2 done with the cleaning until all the corrosion is out of the fuse sockets. Until I figure out how to clean that portion, I am hesitant to put any kind of grease on it.

Do you disagree?

Rob :)
 
RadioMan said:
Google Caig Laboratories
Click to expand...

VERY cool!

I've been in the electronics industry for so long... wonder why I haven't heard of them. That's a great tip... I'll check it out! Thanks!

The corrosion/oxidation on the fuses was actually bonded to the connectors of the fuse. It was part of the metal, and needed to be scrubbed off with the high-speed rotating wire brush. I will be very curious to see how well this stuff works. I think pulling a nasty oxidized fuse out and putting some on will tell the tale.

Rob :)
 
I use DeOxIt first to clean the contacts up and then ProGold to keep 'em clean (ProGold has been renamed - Caig's site has the new name).
Ham type radios use UHF connectors and they always gall a bit after being attached for a while. Just a piece of a drop of the ProGold and they still come right off years later. Zero corrosion. Good stuff!
BTW - I have no connection with Caig, other than being a very satisfied customer.
 
Look at how these fuses from the '99 Burb look. Those are the original fuses, with 9 years, less than 100K miles, always garaged.... Nasty, eh? I think that fuses and oxidation needs to up there on the list with cleaning grounds.

Rob :)


UNRETOUCHED!
Fuses1.jpg



Fuses2.jpg
 
I agree. Its a must do when diagnosing something as computer necessant as these are.

And I have no clue if necesant is a word, if its not, it should be. :)
 
I have ordered the "100%" solution from Caig, which is supposedly able to 'dissolve dielectric corrosion". I purchased the 5% solution (reminds me of Shelock Holmes) which didn't dent the high level of corrosion I showed you in the photos. I'll report back on how well 100% works. I admit I am a little doubtful. After all, it took a dremel tool running at high RPM with a wire brush to scrub it off before. If they have indeed invented a non-caustic chemical mix which is effective at quickly dissolving the corrosion, then I will submit treatment of essential connectors as a regular maintenance task for all 6.5s.

My strategy is to soak the corrosion in 100% solution for a couple of minutes, and then try and flush it with the 5% solution to get rid of it. We'll see, and I'll give you a photo blow-by-blow!

Rob :)
 
I use a fine Scotch Brite with the DeOxIt. Should have put that in my first post.
Let it soak like 5 minutes and brush it off with the Scotch Brite.
 
Radioman, thanks for the tip. I won't be able to use the Scotch Brite on the fuse sockets, though.

Rob :)
 
UPDATE: The cleaning solution from Caig (i.e. DeoxIt) arrived several weeks ago. I ended up pulling all the fuses from the engine bay fuse box AGAIN, and spraying the "100%" solution into the socket, waiting a few minutes, then spraying with the "5% solution" to "flush" the dissolved oxidation away. This took the better part of an hour for each vehicle (decided to do the 'burb as well, given how oxidized the fuses connections were) as I took my time. I didn't re-do the wire-brushing/polishing of the fuse leads, as they still looked GREAT.

It has been about 1 month, and ALL codes are gone, glows work, and all the intermittent gremlins appear to be gone. I was amazed, and I am thankful - I'm pretty sure I got the Tahoe de-bugged. Thanks you guys - you are the best!

Moral of the story is that FUSE OXIDATION is at least as crucial to check and correct as BAD GROUNDS!

Rob :)

P.S. Sorry, no photo blow-by-blow. The oxidation on the fuse sockets cannot be seen, and the oxidation on the fuse leads was shown before. I did try the 100% solution on the fuse leads. The 100% solution does appear to dissolve a fair amount of it, but don't kid yourselves. Your best bet is to use the Dremel tool and the rotary wire brush, take your time and get 'em BRIGHT and SHINY - the high speed rotary wire brush does a SUPERIOR job of cleaning the fuse leads. Don't forget to pull the relays and do the leads on those as well. Make sure you keep track of where the relays go, and their orientation before you go pulling them all out at once.
 
Last edited:
Rob, that's amazing... thank you for following up on this. I'm adding this thread to the Tech Library.

Well done, my friend!
 
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