[natzx7]

I found this on a 2.8 Duramax diesel facebook group, posted by American Diesel Power. I thought it was great, and since I'm having an intermittent issue with my a/c clutch, I think it may help me. Here's the post:

Hopefully the admins will sticky this to the top. Whether you're stock or tuned, intact or deleted this should be something you look for. If at any point, right after tuning, months later, or never modded at all, you begin to see sporadic check engine lights or odd random malfunctions do not despair. It's likely an easy fix. I labeled each of the pictures with FIG XX so you can relate to each on in the text.
COLORADO/CANYON WIRE HARNESS CHAFFING
(hoping this will make it easier to find if its not stickied)
A number of conditions regarding engine performance and air conditioning operation on some 2016 Colorado and Canyon models may be due to the engine wiring harness rubbing on other components. These conditions may include the air conditioning blowing hot air, a fluctuating engine oil pressure gauge, an engine no start or misfire, and several illuminated warning lamps or Driver Information Center (DIC) messages.
Complete the diagnostic instructions in the appropriate Service Information for any symptoms or DTCs found. If the diagnosis does not lead to a resolution, check for chafing of the engine wiring harness in the following areas, perform any necessary wiring repairs and reroute the harness.
• Air conditioning (A/C) compressor, A/C compressor suction and discharge line manifold, A/C line and A/C compressor clutch (Fig. 9)
A wiring harness concern in these areas may cause:
• The Check Engine light to illuminate and the engine to run rough or not start. • The 4WD warning lamp or StabiliTrak warning lamp to illuminate. • The oil pressure gauge to read erratically or read no oil pressure. • The A/C to not cool. • An open fuse in the Underhood Bussed Electrical Center (EBEC).

Fig. 9
• Serpentine belt near the fan clutch wiring harness support bracket (Fig. 10)
The support bracket may be out position and allow the harness to run on the belt, which may cause:
• An engine crank, no start condition or the engine to run rough or misfire. • The Check Engine light or other warning lamps to illuminate, such as the 4WD warning lamp or StabiliTrak warning lamp. • The A/C to not cool

Fig. 10
• Exhaust heat shield near the right rear of the engine (refer to Bulletin #16-NA-081) (Fig. 11)
A wiring harness concern in this area may cause:
• The 4WD warning lamp or StabiliTrak warning lamp to illuminate. • The Check Engine light to illuminate. • A Reduced Power message on the DIC. • An open fuse in the EBEC.

Fig. 11
• Transmission bell housing bolt/stud (Fig. 12)
A wiring harness concern in this area may cause:
• The 4WD warning lamp or StabiliTrak warning lamp to illuminate. • The Check Engine light to illuminate.

Fig. 12
• Coolant pipe and clamp tabs between the engine and cowl (Fig. 13)
A wiring harness concern in this area may cause:
• The 4WD warning lamp or StabiliTrak warning lamp to illuminate. • The Check Engine light to illuminate.

Fig. 13
• Brake fluid level switch (Fig. 14)
A wiring harness concern in this area may cause:
• The Check Engine light and service brake lamp to illuminate. • A Low Brake Fluid message on the DIC.

Fig. 14
• Transfer case encoder motor (Fig. 15)
A wiring harness concern in this area may cause:
• The Check Engine light or other warning lamps to illuminate.

Fig. 15