07 w900 speedometer

Not 100% sure but I think the '07 dash is multiplexed and a 6NZ I believe was produced prior to the dashes being multiplexed. May have to replace the speedo and tach to an older style that will communicate directly with the speed sensor and engine ECM. May want to confirm what I said with someone a bit more knowledgeable than myself first though.

 

It may be a setting in dash or cat computer. If 6nz is yr I think it may be a matter of programming, there are a few communication options in ecm. Some cats supported the newer style trucks some didnt but I cant remember specifics.

 

6nz will work with multiplexing. More then likely the parameters never got changed in the cecu. Engine parameters might also have to be changed to allow the signals out on multiplexing vs hardwired.

 

You need to make sure that your 6NZ is transmitting the speed over J1939. This should just be a parameter change with Cat ET. Some older flash files do not support J1939, if that's the case, you just need it updated to the newest file, then set the parameter. Your speedo is controlled by the Namux system, which gets the speed signal over the J1939 data link. The tach works the same way, so if your tach works, then your 6NZ is already transmitting J1939, so it's just a parameter change to get the speedo and odometer working.

You will also most likely have to set the speed signal pulses per mile for accurate speed and miles with Cat ET as well. The easiest way is to find the data sheet for your drive tires (most are online) to find rotations per mile for your tires, multiply by your rear ratio, then multiply by VSS tone ring teeth (99.9% chance that it's 16) to give you a big number to program in the ECM for accurate miles. For example, if your tires have 490 rotations per mile and you have 3.90:1 rears, 490 x 3.90 x 16 = 30576 pulses per mile.