2005 volvo D12 missfire please help

You can R&R a harness yourself. Installing a harness in the engine compartment is usually Plug N Play, take pictures first of the routing, the electrical connections to the components and any brackets and hardware that supports the harness.

Once you order the new harness, compare it to the old harness to make sure everything matches up.

If all looks good, just remove the old harness and install the new one. Make sure you have a good selection of different sizes of zip ties too.

 

what were the active codes when this truck does miss idle

 

Did you ever find out what was wrong with your truck. My truck started doing the same thing a few days ago. Was wondering where I need to start looking. Thanks

 

My 2004 D12 has been doing the same thing. I worked it down to harness after swapping injectors and fiddling with connections. Went to my local Volvo dealer and the grey head parts guy I like. He recognized what I described , intermittent #5 not working. Some years ago Volvo came up with a repair sub harness. It replaces the injector part of the harness to outside the rocker cover a foot or so where it is patched into the existing harness one wire at a time. The part number is #21625276. I just got it late today so have not yet installed it. Over time the oil degrades the insulation on the wires and destroys conductivity. I’ve seen it happen on cars. The complete wiring harness is $900 plus, this part number is around $400, less than half.

 

After you go through the install process you are going to wish that you paid the extra $$ for the whole harness....