Jake wiring

[Rawze]

(01-02-2023 )Smiling lemon Wrote:  ...
The ECU wants to see those two wires grounded out for level three jake. I spliced in wires up at the cecu that go to a switch that is grounded out and when I flick the switch Jake's and the dash light up. The smartwheel module puts out a voltage signal to the cecu not a digital and I tested to see that the cecu receives the signal on the pins but it doesn't respond. The only jake motion I have gotten was grounding out pins 11/12 from the cecu and I get jake light and jake solenoid activation. At this point my guess is that something is wrong on the board of the cecu, a relay or something went out and it no longer grounds those pins. I haven't been able to find a board schematic or someone willing to diagnose it

Just some related info to consider ...

Many of the buttons on my prostar (other brands of trucks may use this strategy too?) actually work by sending a specific voltage instead of an on/off. for the cruise and resume, and the engine brake and other buttons, it will send 3.3-vlots for one button, and 2.7volts for a different one, and 4.5 volts for a different one yet. - These are not digital signals.. but a steady voltage, and the cab controller reads the voltage and determines if it is in range or not.. and then acts accordingly.

This works great .. until the fuses in the fuse panel get tarnished/discolored a tiny bit over time. Then suddenly the cruise button does not work.. or the engine brake buttons stop responding, etc.. because the voltage they send has dropped a tiny bit and the cab controller rejects the signal.

SO.... HAVE YOU cleaned all the connectors to the device not working well, and replaced all of the fuses in the fuse blocks with new ones before assuming that the cecu itself is the problem?. That is one of the things that has gotten a lot of people on these newer trucks, and is far more common of an issue that most would think. Fuses are all perfectly good... check out just fine.. but replace them, and things start working again, ghosts problems in the dash and/or button issues will clear up. -= Terrible design if you ask me, but who am I.

I have an article on just this, located here...
ref: http://rawze.com/forums/showthread.php?t...1#pid12861


also.. there are many reasons that the engine brake will not engauge. a person needs the CECU software to see if the actual signals are being read into, and sent out of the device properly, and without that it is anyone's guess. Same thing for the engine side. they are 2 seperate systems, each with their own requirements.