JA101

Oh okay, thank you for the info. Assuming continuity is okay, would that point to an ECM issue, or is there a switch on the differential that could be bad?

I dont believe there are those solenoids behind the cab. I do see a couple solenoid type things closer to the mid point of the frame by the side rail.

Im not sure, I will go check. I do know it was affected by the frame issue they were having, so its a new frame. I see things printed on the wires, such as UJ1-3-D.8. Is that what you mean?

Ill go check it out and get back

Yes, all white. Now that I think of it, how exactly does this light get its signal? Is it a simple switch on the differential? I wonder if I am just hearing it try to engage but it never actually does. Its going to the mechanics pretty soon so I can have it checked.

Hello, On my Mack, the diff lock switch lights have always acted up. One switch had no indicator light, and the other is very dim, but works. I removed the switch with the broken light, dismantled it, cleaned it up, and soldered in a replacement red LED, figuring that was the problem. I replaced the switch, and no light. So I swapped plugs, and now I have a bright indicator light on that switch, and none on the one that was dim but working. So it seems like wiring connector #1 has a fault somewhere down the line. From my understanding on working on other vehicles with similar switches, there is a relay somewhere that sends power to the switch indicator telling it to turn on when engaged. But... where is that relay? And is that the problem? Macks are very hard to find diagrams for, I can't find anything useful to help find it. I am guessing it is either behind the dash or in that relay panel on the passenger side, but again, nothing can be found online. Anyone encounter this before?

Oops, yes, manual. Didn't know there were also autos. Should also say I am posting this for the owner who does not use online anything. I will see if I can get the yoke checked.

I have a 2004 Mack Granite I got recently with the 427 and Mack transmission. For the life of me, I cannot downshift it. It upshifts totally fine, but it will not downshift. Other people have tried and cannot get it to downshift. It only grinds. Sometime it can be forced to downshift, but will grind the whole time. Tried it all different ways, speeds, etc. It just will not downshift. What could be wrong with the transmission m ? I think something is wrong with it. Considering swapping for an 8LL...