Heavy Equipment Repair Questions? Ask an Expert Now.
Hi and welcome to JA. I am Buddy, and i will try and help you out.
The VCU normally on a columbia is in b-pillar behind the passenger seat on the side wall. There will be a screw you turn one revolution and side panel will open. If it is not in there, look on opposite side behind drivers seat. If you have anymore questions or info. Just ask.
Also here is the troubleshooting info for fault sid 254
The following procedure will troubleshoot SID 254.?
Perform the following steps to troubleshoot 254 12, DDEC-VCU internal error.?
Note: Turning the ignition off for more than 10 seconds will reset the DDEC-VCU.
Thanks for the reply.
Those 2 codes kind of go together. That is more then likely the reason the truck will not start. Here is the troubleshooting info on that code SID 248.
Perform the following steps to troubleshoot a loss of communication between the VCU and PLD.?
Note: If fault code is inactive and the engine starts, the most likely cause is a poor electrical connection, careful inspection of all mentioned connectors below is necessary.
Perform the following steps to resolve a proprietary datalink fault.?
Perform the following step to troubleshoot a DDEC-VCU internal error fault.?
Perform the following steps to resolve a DDEC-VCU internal error fault.?
Buddy, I have a couple more questions for you....On the 16-pin connector there is no 16/5 and no 16/9 pin in the 16 pin connector ? ( Question #2. ) How do you go about restoring voltage to wire 16/15 small engine harness (as said in step 9) ?
Let me tell you what happened to truck. As driver was driving, the drive shaft broke and somehow severed all the wires in the middle , each end was still intact at their connecting ends. Could this cause a short or damage to the VCU , by all the severed wire touching one another? Because the truck just quit running and since has never started again and the 254 fault is still there. Also, when we turn on key, we do get dash lights, and it does crank, but won't kick over. Should I just replace VCU ?
IT WILL START AND RUN ON ETHER (BY THE WAY).
On the 16 pin connector it is referring to the 16 pin plug at the pld. This is the ecm on drivers side of block. If that is where you are checking, let me know, and i will try and pull a wiring diagram for that circuit. That starts at step 10. I would not buy a vcu yet. If you had a test one, or a friends truck that had one, i would try a test one first just to see if it will crank. If you do have to replace the vcu, the new one will have to be reprogrammed.
Let me know if you are checking at the pld, if so i will try and pull up a wiring diagram and see where those wires go to.Also what is the last 6 of your truck vin
pin 5 of the 16 pin connector should be 439C. This will be the power supply to the pld.
pin 9 of the 16 pin connector is a ground.
I am attaching wiring diagram also. There should be a Y in the harness about a foot from the pld. Then about 6 inches down there should be 2 plugs. That is where the ground and voltage supply come into that harness from another harness. Might be a easy test point. I am going to try and find other side of that harness.
DIAGRAM <<<<<< click there for diagram
Just zoom in on diagram to see it better.
I just found another diagram that shows the power wire coming from a 15 amp fuse and the ground going straight to battery. The fuse is probaly in or near your battery box.Here is that diagram. Go to page 5 and zoom in and look at 439C wire
DIAGRAM2 <<<<< click there
I hope this helps you out.
buddy, the diagrams did not upload , could not see anything on page. please try again.. thanks
Here they are
Let me know if they work that time. If not we will try a different route
Thanks for the reply.
Normally they would not need to be reprogrammed if something like that happened, but i have seen strange things happen before. I would suggest to carry your vcu and your pld to your local freightliner dealer and see if they are able to connect to them. If they can not, then they would try and reprogram them to your engine serial number.There is no other way to clear the code. I hope this helps you out. If you have anymore questions, just ask.
ok thanks ....guess that is about the only choice at this point.....i'll keep you updated ....maybe even have another question for you??? thanks
Let me know what you come up with.