So, a few years back we decided to purchase a 1998 Chevy Suburban 6.5L TD K2500. We have figured out most of the electrical gremlins(personally I like to call them demons) but this one is a pickle!
So, We have just went through 3 climate control panels. For some reason they work great for a few weeks and then poof the air conditioner button stops working/lighting up. We checked the wire harness a million times and nothing. Well, my husband just recently had to replace the alternator! The regulator went bad. However upon doing this, he was playing around with the climate control switches and turned off our check engine light which has been on even since we changed and moved the PMD.
We started the engine back up and boom the light came back on. So, this leads me to the question of besides the wiring harness directly behind the climate control, what other wires/harnesses should we be checking? We can't keep having issues with this because we just had a baby and winter is fast approaching here in Illinois.

 

Bump

 

What did you use and where did you get your PMD relocate kit?

Did you relocate to the front bumper?

It is best to use only Made in the USA extension harnesses for PMD relocation kits

Leroydiesel.com is a good source 6.5 diesel stuff.

What codes are you getting?

Have you checked cleaned and added grounds?

I have been switching out my engine harnesses as I work on vehicles. The harnesses on all my 6.5's leave a little to be desired.

Joe Zurek - Zurek Automotive west of Ashkum is good with electrical issues.

I would suggest doing the grounds before chasing anything else.

Have you done the battery bolt mod? I use 1 1/4" Allen screws with washers and nuts.

If the Allen screws are tapered at the ends, they need to be square cut so as not to strip in the battery.

I have posted probably here and at the other forums mentioned what to add for grounds>

One of the grounds to add goes from the ground on the heater blower to the dash mount bolt just inches away. Need a 5/16 eyelet and a way to add a wire to the ground.

I add a ground to the back stud on the engine where all the grounds go, to the frame by the starter, to the battery box on the right / passenger side, to the injection pump and to the PMD heat sink.

 

Ok, so the codes we are getting is because of the new ECM and we already did PMD relocation kit and moved it to another location. The issue isn't with PMD or ECM anymore. We even keep a back-up PMD in the truck. All that is fine. Just had the glow plugs replaced. 2 new batteries, cables, and alternator.
We have also rewired the batteries, alternator, all the wiring on top of the engine, replaced all the fuel lines, replaced all the brake lines, replaced all fuses and relays, new glow plugs last week, and replaced the climate control 3 times. We also recently replaced the harmonic balancer, had the timing checked, and replaced the serpentine belt.
Also, we have a neighbor who is a licensed diesel mechanic who checked over the wiring and found one glow plug wire that rubbed through due to it wearing on the frame.
We have tracked the electrical short down to the climate control panel. We have already replaced 3 of them and I beginning to think it is in the wiring harness somewhere. Although we had replaced the radio and a mechanic friend of ours thinks that could be the issue because it could be pulling way too much juice. The crazy thing with the control panel was it did this after we replaced the bad alternator(regulator had gone bad).

 

Also, besides this latest issue with the alternator and climate control the truck runs fine. However we both know that messing around with the climate control should not be turning off the check engine light so we want to prevent future problem.

 

I would go back to checking , cleaning and adding grounds. I have a few posts on which grounds I add - directly to the battery. I have seen the stud at the back of the engine lose ground several times. And the ground to add from the heater blower to the dash mount bolt just niches away may help you.

New parts does not = good parts. It should but it doesn't work that way.

Check the wiring going to the heater blower. The connector just above and to the left of the blower gets toasted a lot - hence the adding of the ground to the dash mount bolt. Seems like most of the time it's the ground that gets baked.

If the wire is toast or looks toast, change your heater blower. Toasted wires are a good indication the your blower is drawing to many amps