back with another issue
 

my 06 chevy express is acting up again. While riding down the road it acts like it is cutting off for a second then keeps on going. It got bad enough coming back from the job earlier I thought I was going to have to get it towed. It did it randomly last week but I could not find anything. I stopped at a gas station on the way back today and popped the hood. I noticed that the positive cable on the battery was a little loose so I tightened that up. Rode fine for a few miles then right back to it again. This time I noticed every time it seemed like it shut off the temp gauge would drop to zero and as soon as it hit back the gauge would come back up to normal. Several mile later it would be at 205-210* then it would fall to zero then jump up to about 260* on the gauge then after a minute or so would fall back to the 210 range. I am assuming it is a wiring/ground issue. Has anyone run into this before? It threw the check engine light so i checked that with the reader and it has code PO118 in it twice for temp gauge reading too high and then code PO455 for what I am seeing may be the gas tank vent valve 9which is apparently a common issue with these) I don't think either of the codes are the actual problem and most likely got thrown because of the erradic gauge?

It is a 6.0 automatic with roughly 185K miles

Thanks

Re: back with another issue
 

I have found the biggest issue with these around your mileage is poor grounds and or corroded connectors especially the ECM ground wire that attaches to the chassis down under the radiator support along with the main battery ground cable....

The ECM wire to ground should be cut off and replaced with a new (preferably Gold Series) connector that is soldered to the wire.

Sandpaper the chassis well, plus any and all cables that may conncet at this point.

Then look for and find every ground cable on the engine....some are under and near the engine mounts, some at rear of cylinder heads...each one needs to be cleaned very well....remove the bolt, clean the area and the connectors with sandpaper until shiny then reassemble.

The temp gauge issues are pointing to bad grounds...

Erratic readings of temp will cause the ECM to provide incorrect fuel mixtures and spark timing...

Finally, remove both battery cables from the battery and clean the ends of each cable and the mounting points to the battery...

:chevy::chevy::chevy:

Re: back with another issue
 

Thanks for the detailed reply on where I should be looking. I am hoping to get it all taken care of tomorrow or Friday.

Re: back with another issue
 

Aussie nailed it.

One more grounding issue that bit me once in my '84 S10 was a bad ground to the dash. Erratic gauges and flickering gauge lights. Luckily it was an easy fix and I was super lucky because I accidentally bumped the wire with my leg and that forced the problem to be repeatable with the wiggling of the wire. It was a small ground strap that attached at the left-hand side bottom of the dash, right by the little bracket that attached it to the left kick panel. The vehicle was only about a year old at the time when I started noticing it, so probably loose from the factory. I only mention this because it's one more possible ground.

Re: back with another issue
 

I do believe this is my issue. The original one down where it attaches to the side of the engine block is loose it in the connector and the braided one that leaves there and goes to the frame is totally green with corrosion. I will pick up a new one in the morning. That bad boy is $50 :waah: While under there I also noticed the oil cooler lines have a lot of rust on the pipe sections so gonna go ahead and replace them as well.

Gotta wonder sometimes what engineers are thinking though, of all the places to mount the ground to the engine they pick directly behind the AC compressor. I hope the bolt is not longer than the gap.
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Re: back with another issue
 

Check inside the protective covering of the positive cable. My old d-max had weird issues and I found at one of the batteries corrosion had built up inside and behind the bolt and contact surface. Had to hit it with a pick to notice what it was, clean em up really good and took care of my problems.

Re: back with another issue
 

I think the bottom of the negative cable is what the issue was. Here are a couple pics of what I took off. I am going out on the maiden drive in the morning and hope to have no issues.......but I know my luck and history with the truck lol

Biketopia there are no covers on the cable ends due to having the 35' boom on the truck. Several leads are run to the battery so the boots were in the way and removed

Re: back with another issue
 

The 6.0L in my '06 Silverado was doing something similar, and it ended up being the crank position sensor.

Gary

Re: back with another issue
 

thought I would come back and update this in case someone else runs into a similar problem. It ended up being the temperature sender wiring right near the plug. For some reason both wires had been cut at some point and were just twisted together with not even tape over them. Over the course of time, I assume from bouncing around, one of the wires was loosened up and I guess making intermittent contact. I bought a new pigtail from Rock auto and used heat shrink and it has not had any symptoms since. Now if Baltimore would fix their potholes so i quit losing hub caps .............. :lol:

Re: back with another issue
 

A old mechanic told me you have to be a electrician now to fix new cars and trucks

Re: back with another issue
 

Glad you found it. Thanks for closing the loop.