97 6.5 engine wiring harness needed

[DieselDavy]

Hi guys,
I need a wiring harness for my 97 6.5 2 door Tahoe. Any ideas as to where to find such a thing?
Part numbers?
Thanks,

[More Power]

You could try a GM dealership's parts counter, but it may be hard to find. The 1995 models were unique, with not a lot of commonality with the 1994 or 1996 models.

What happened to the original harness? What part of the harness is damaged? I'd think about rebuilding what you have. You can buy new electrical connectors and generic automotive wiring is easy to find. Jim

[DieselDavy]

Thanks for replying Jim!
(it is a '97 not '95 as you indicated in your response)
We don't know what is wrong with the truck Jim! New pump/PMD, Crank sensor, replaced PCM, replaced/repaired various connections and grounds, checked fuel quality and still no Joy! Fuel is clean and air free at the pump.

Here is what the tech has done in his own words:

"P0251 Pump Cam reference Pulse Error
P0370 High Resolution Circuit Fault

Started by installing an encoder sensor (cam sensor). Cleared codes and started truck. Truck still didn't have a signal from cam sensor. It was running in base timing and creating cam misfires per our scan tool. Installed new GM crank sensor. Same result after starting truck. Pulled injection pump and mounted on test stand and found fuel solenoid response time was too long. Pulled head and rotor apart and checked keyway. Installed new armature and set gap. Installed back on test stand and calibrated pump. Installed old encoder sensor and calibration went well. Installed on truck and truck acted same as before. Tested wiring from encoder sensor to PCM. The resistance was OK. Checked for 5V reference and computer was supplying ground. Everything checked OK. Repaired ground Y-connection in factory harness. Kennedy diesel supplied alternative PCM. Truck acted same as before. Installed complete new injection pump/PMD. Truck acted the same. Double checked and repaired ground wires on back of motor and cleaned all connections for grounds on engine and batteries. Installed new encoder connector pigtail on engine harness. Truck acted the same.

Truck cranks 10-12 sec and starts. Truck then runs at full timing and still does not show actual timing reference or injection closure.

If you have any questions on this truck please do not hesitate to ask."

Jim, What is the reluctor wheel and could it be a problem. Someone mentioned it on another forum. I thought it would have been the same as Crank sensor which has been replaced with new, but I was told it is in with the timing chain.

Thanks for any advice you might have.
Dave

[Robyn]

The reluctor is part of the crank timing sprocket and likely not an issue.

The culprit is possibly the valley harness.

The wrinkle loom around the wiring can and does over time, due to heat and vibration cut through the wires.

Remove the intake, and then the harness.
Get that puppy out on the bench and dissect it carefully, paying special attention to the hi res wires.

I have personally seen wiring in these harnesses worn through.
This harness was available through GM parts, but the last one I bought was hard to get.
The bailout saw many of the 6.5 parts discontinued.

If all is well here, check things from the main plugs at the rear of the engine back to the ECM.

Be sure to check the connections at the main engine harness for corrosion.

DO NOT "BACK PROBE" THESE CONNECTORS, AS THEY ARE SEALED AND CAN BE DAMAGED.

If you find a broken wire in the engine harness, simply cut out the bad part and splice in a new section.

I would recommend soldering and covering the splice with heat shrink tube, rather than crimp connectors, due to the area that its in, plus the critical nature of the circuits.


********************UNHOOK THE BATTERIES FIRST *************


If by chance you don't find anything in the engine harness, make an extension for one leg of your VOM and wring out all the wires from the main engine harness to the ECM

A factory wiring manual can likely be found on ebay
Tahoe
Burb
Pickup

These all used the same basic wiring, and the manual will have the complete diagrams of pinouts, colors etc.

Go after the engine harness first, that my bet.

Keep us in the loop

Missy

[More Power]

Reported problems with the engine valley harness include:

1- Pinched harness that was inadvertently clamped between a runner of the intake manifold and the cyl head. This can cut wires or short to ground wires.

2- A portion of the harness positioned in such a way that it crosses a sharp edge, which cuts through the loom and individual wiring insulation, resulting in shorts to ground.

3- In areas of the country where salt is used on winter roads, corrosion can affect the underhood wiring. Look at the 15-pin connector at the rear of the engine valley and inside/beneath the underhood electrical center (where the relays and fuses are).

The "cam" signals are actually generated inside the optical sensor portion of the DS4 fuel injection pump. There are no "cam" sensors used in this engine. The DS4 optical sensor indirectly produces a cam signal. Jim

[DieselDavy]

Thanks Robin and Jim!
As an electrical engineer, I totally understand the issues you are discussing here. My issue is with time and distance. I have NO time and the Tahoe is 40 miles from me!
I have three jobs, trying to get a rental house ready to sell and the normal family issues to deal with!
I'm first going to copy and past your responses into an email and get them to the tech.
He's worked on these engines as long as they (6.5s) have been around and he still wanted any inputs I could get! (he said this one is the worst one he's ever worked on! Great....)
I'll keep you posted....
THANKS AGAIN!
Dave