Wiring Harness Issue

[pjmia96]

Hello, I am new to this forum and this is my first post.

I have a 1996 GMC Sierra 3500 with the 6.5 Diesel. This truck had a worn out motor and slipping transmission. Currently in the process of finishing a motor and tranny swap on this truck with a motor and transmission from a 1999. I chose to not use my original engine & transmission wiring harness from my 96 because it was in very rough shape. I decided to use the harness from the 99 instead. Everything seemed to go well until I got to these three plugs (Shown in photos) that are behind the glove box. I see they are not the same plugs and will not connect together.

So, my question is what are my options in this situation? I do notice that each wire or pin has a corresponding letter. I also notice that the bigger white plug coming out of my dash, and the bigger black plug coming off of my newer harness has a lot of the same color wires associated with the same letter on each plug.

Is it possible to change the connector an make this work? I cant seem to find a printout diagram for these particular connections.

Any help would be greatly appreciated

Matt

 

[99xcss4]

are you staying diesel or did you swap to gas if you swaped to gas that could be the problem

 

[Hipster]

Hello, I am new to this forum and this is my first post.

I have a 1996 GMC Sierra 3500 with the 6.5 Diesel. This truck had a worn out motor and slipping transmission. Currently in the process of finishing a motor and tranny swap on this truck with a motor and transmission from a 1999. I chose to not use my original engine & transmission wiring harness from my 96 because it was in very rough shape. I decided to use the harness from the 99 instead. Everything seemed to go well until I got to these three plugs (Shown in photos) that are behind the glove box. I see they are not the same plugs and will not connect together.

So, my question is what are my options in this situation? I do notice that each wire or pin has a corresponding letter. I also notice that the bigger white plug coming out of my dash, and the bigger black plug coming off of my newer harness has a lot of the same color wires associated with the same letter on each plug.

Is it possible to change the connector an make this work? I cant seem to find a printout diagram for these particular connections.

Any help would be greatly appreciated

Matt

You want answers but didn't tell anybody what you're up to. You might want to go into detail.

 

[99xcss4]

also if you did do a gas swap you will also need to swap a gas gauge cluster and get a dash/under dash interior harness for a gas truck note that harness also has the interior fuse box with it and the junction box that goes in the fire wall on the drivers side is part of it as well

 

[Hipster]

also if you did do a gas swap you will also need to swap a gas gauge cluster and get a dash/under dash interior harness for a gas truck note that harness also has the interior fuse box with it and the junction box that goes in the fire wall on the drivers side is part of it as well

This could be relevant info if he wants to disclose wtf he's up to.

 

[pjmia96]

are you staying diesel or did you swap to gas if you swaped to gas that could be the problem

I am swapping a 1996 6.5 Diesel Engine with the transmission attached for a 1999 6.5 Diesel with transmission attached. I am trying to use the Engine and Transmission harness from the 1999 truck in my 1996 truck but three plugs next to computer/ECM will not plug in.

 

[pjmia96]

This could be relevant info if he wants to disclose wtf he's up to.

Swapping 1996 motor and tranny (6.5 Diesel) for a 1999 motor and tranny (6.5 Diesel) The 99 trucks motor and tranny harness will not plug into the 96 harness coming out of the dash. I would not swap a diesel for gas this is the exact same motor 3 years newer.

 

[pjmia96]

If I was swapping a gasoline engine I would have wrote that in to begin with. This is strictly a Diesel 6.5 motor and transmission swap with the exact same motor and transmission 3 years newer.

 

[99xcss4]

the truck you got your engine transmission and harness from go back to it and take out the dash and pull the dash/under dash harness from that truck maybe some plugs changed though out the years

 

[GoToGuy]

I would have both wire diagrams available, depin the plugs on your old engine . Depin the plugs on new engine. Repin the old plugs into the new engine harness.
You need to realize, we can't see what your doing. Pretend your describing your problem to your blind friend. And if you're asked for clarification, and get twisted, well you know what happens.