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I replaced the ECM to engine wiring harness on my 2008 M1079 A1R due to multiple occurrences of connection issues with all three of the pressure sensors - the oil pressure, boost pressure, and atmospheric pressure sensors would throw codes and the boost pressure sensor in particular would put the engine in limp mode and cut off all boost from the turbo making the truck REALLY difficult to drive.
In the process I found that the new harness didn't match the existing injector harness. Apparently CAT changed the design and you'll see why in a moment.
My truck has always had an intermittent slight roughness to the idle - it only seemed to do this after idling for a while and I figured it might be related to the emissions programming since the C7 trucks have catalytic converters and there are directives about putting them on high idle if they are going to sit and run for an extended time. It wasn't serious enough to consider an actual problem and never affected performance, etc. I now think this was likely due to the injector harness being damaged and shorted. Has not occurred since though I only just completed the repairs yesterday.
So the injector harness had to be changed to match the new engine to ECM harness, and in the process I found that the wiring harness had shifted and pulled loose from one of it's anchor points due to hardening and shrinking of the wire insulation and braided plastic sheathing. This caused the harness to rub against one of the valve springs to the point that it was down to the bare wire and was clearly shorting at least intermittently to the valve spring. In addition the Amphenol connector used for the rocker cover riser had failed and was allowing oil and condensation into the plug's electrical connection.
Here is the harness retainer that pulled loose from the riser (could not put it back - the harness is "baked" into a very rigid condition):
CAT has an updated harness that changes the bulkhead fitting and the main connector to the injector sub-harness and a "clip" that guards the wire in this exact location:
New style harness connector:
These are the part numbers for the harnesses and the "clip" (guard), and the new style retainers that are christmas tree style zip tie lugs:
(1) ECM and engine to injector sub-harness: 6150-01-524-8191, 229-9765
(1) Injector sub-harness: 6150-01-524-8364, 520-1511
(1) Injector harness "clip" (cable guard): 519-5559
(eight) Cable strap: 206-1345
The updated ECM and engine to injector harness (229-9765) also eliminated the lift pump fuel pressure sensor connector. Apparently it's not used anymore and indeed my ECM didn't care and doesn't even seem to have a data stream for that sensor and is still able to calculate fuel consumption - so one less thing to worry about going forward.
In the process I found that the new harness didn't match the existing injector harness. Apparently CAT changed the design and you'll see why in a moment.
My truck has always had an intermittent slight roughness to the idle - it only seemed to do this after idling for a while and I figured it might be related to the emissions programming since the C7 trucks have catalytic converters and there are directives about putting them on high idle if they are going to sit and run for an extended time. It wasn't serious enough to consider an actual problem and never affected performance, etc. I now think this was likely due to the injector harness being damaged and shorted. Has not occurred since though I only just completed the repairs yesterday.
So the injector harness had to be changed to match the new engine to ECM harness, and in the process I found that the wiring harness had shifted and pulled loose from one of it's anchor points due to hardening and shrinking of the wire insulation and braided plastic sheathing. This caused the harness to rub against one of the valve springs to the point that it was down to the bare wire and was clearly shorting at least intermittently to the valve spring. In addition the Amphenol connector used for the rocker cover riser had failed and was allowing oil and condensation into the plug's electrical connection.
Here is the harness retainer that pulled loose from the riser (could not put it back - the harness is "baked" into a very rigid condition):
CAT has an updated harness that changes the bulkhead fitting and the main connector to the injector sub-harness and a "clip" that guards the wire in this exact location:
New style harness connector:
These are the part numbers for the harnesses and the "clip" (guard), and the new style retainers that are christmas tree style zip tie lugs:
(1) ECM and engine to injector sub-harness: 6150-01-524-8191, 229-9765
(1) Injector sub-harness: 6150-01-524-8364, 520-1511
(1) Injector harness "clip" (cable guard): 519-5559
(eight) Cable strap: 206-1345
The updated ECM and engine to injector harness (229-9765) also eliminated the lift pump fuel pressure sensor connector. Apparently it's not used anymore and indeed my ECM didn't care and doesn't even seem to have a data stream for that sensor and is still able to calculate fuel consumption - so one less thing to worry about going forward.