P0748 code
 

Me again.

2004 Silverado 2500 HD with Duramax and Allison trans.

It's started throwing a P0748 code and seems to be in limp home mode. I can clear the code and it will be ok for about a minute then comes right back.

P0748 is Pressure Control Solenoid A, and my research tells me to look for bad connections, broken wires and such.

Anybody happen to know where this thing is located, or have any additional thoughts?

TIA -

K

Re: P0748 code
 

I can't help with this.
I can you a TTT and a U tube video.

Re: P0748 code
 

Thank you -

Re: P0748 code
 

Fixed it.

Here's the thought process:

As I mentioned, P0748 is Pressure Control Solenoid A, and the world wide web was telling me to look for bad connections, broken wires and such.

I had the TCM out of the truck last November when I was doing that ECM swap, so I thought it was possible I might not have re-made the connections well, or something like that.

Upon pulling the TCM back out I noticed the main harness of about 300 wires was laying on the power steering pump pulley and had worn completely through the convoluted conduit protective sleeve.

I peeled the sleeve off and looked very closely at all the wires. There was one very tiny light blue wire which had worn through the insulation and I could see copper, although it looked intact. Maybe it was shorting to ground via the pump and pulley.

Anyway - I cut the wire at that point and put a splice in there and put it all back together. Unhooked the batteries in order to do all this, hooked them back up, cleared the code and - problem solved.

Everything is buttoned back up now (with a new and better wire harness routing) and I am back in business.

Thanks,

K

Re: P0748 code
 

Good Work :metal:

Feels good to get it Fixed:chevy::chevy: