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Discussion Starter · #1 · (Edited)
*sigh* OK, I've been a member here for three years, and you guys know I'm a pretty regular contributor. Thanks to the many selfless people on this forum, I have fixed many a little problem with my Suburban and Tahoe and made it a better, stronger, more reliable vehicle as a result. Frankly, without this forum, I would probably have sold the thing by now. So.. thank you!

All right, so what's the title mean? Well, over the past month, I've been running into a number of irritating little problems on the Tahoe, all manifesting themselves as intermittent, with the occasional DTC thrown in. The list:
  • DTC 44 and 45 - the EGR error codes. Sometimes the codes would be thrown and the truck would lose the wastegate solenoid function, resulting in no boost and lots of black smoke, no power. Very scary on the freeway.
  • DTC 29 - The "glow plug" fault - this was also intermittent, and would cause the glow plugs to not function. The truck would start, but would not glow the plugs.
  • WIF light - Yes, sometimes the "Water In Fuel" light would flicker on, usually under heavy acceleration. There were times when the EGR codes would come on at the same time.
I admit it - I took the codes at face value, and ended up replacing the EGR solenoids (both of them), the vacuum harness, the glow plug relay, and was looking at the ignition switch as well. I also drained the fuel filter and checked for water (didn't find any).

As you guys probably know, I have been trying to diagnose the DTC 29 problem, when JFaire (good old Jim) sent me some links to previous threads on problems with WIF lights, glow plug problems, etc. There was enough similarities in the symptoms that I read the entirety of the threads and checked the solution. Awww, my grounds CAN'T be bad... I've checked them all visually, said I.

Well, WRONG. I decided to pull all the grounds apart and clean, tighten, and repair anything I found. Well well well...
  • Battery Ground to Engine..Driver's side... Looks good. Take it apart, looks good. Polish it up anyway and tighten.
  • Battery Ground to Engine - Passenger side.. same deal.
  • Multiple point-grounds at rear of passenger side.. Looks OK, take it apart... a bit of corrosion, but nothing too serious.
  • Engine Ground to Frame, Body Ground to Frame... Looks OK...start taking it apart... OK, NOT OK.
Here's what I think happened. When the body was lifted 3", the lift installer did NOT change the length of the grounding straps. Over time, the grounding strap from body to frame was stretched until it was hanging on by... nothing. In fact, you couldn't really visually see any problem. When I took it apart, however, it was clear that one of the straps, although appearing to be fine, was in fact disconnected, and was waving in the breeze. When the Tahoe was stopped, it looked fine, and made temporaty contact. I think that when I hit a bump, or when I was on the freeway, the strap would swing away when a gust of wind would hit it, or when I hit a good bump. I think that this has been causing a number of problems.

Anyway, I went to the stereo and the auto store, and bought 4 ga wire, and then to NAPA for copper heavy duty end links. (see photos). After spending around an hour or so fabricating new cables and polishing the living daylights out of everything... everything works. Glows glow, truck starts, no problems.

GMCTD, Jfaire, Kevin... you were all correct, and I am humbled and repent in dust and ashes.

The following photos show the finished, cleaned and polished and/or repaired connections. As I mentioned, they all looked normal before the repairs.

Photo 1: here's the multi-point engine ground that also has the engine to frame ground strap. I thought the braided copper strap was completely wimpy, and built up a 4 ga cable with copper ends. I also took steel washers and did a connector 'sandwich'. Also note the lock washer.


Here's the ground connection from the driver's battery to the engine. Looks fine. Took it apart.. Still looks fine. Polished and tightened anyway.


Here's how my frame ground looks after new cabling and cleaning.


Here's what those copper heavy-duty end links look like. I like 'em. I used a heavy-duty crimper and squeezed the ever-living daylights out of them. They are on there very tightly and securely with good electrical connection.


Frankly, I think that replacement of grounds (on a new acquisition) and cleaning of grounds should probably be done on a yearly basis. I'm going to do it.

Thank you so much,

Rob :)
 

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Although I haven't done it yet and old timer told me after cleaning any grounds or battery connection to put some terminal grease on them (liberally) and it will help from corrosion.
 

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