US Shift Quick 4 controller for 4R70W

[mgb0302]

For all of you with a 4R70W and a US Shift controller.

When I am in the top available gear (either OD or 3rd with OD turned off), my electronic speedo does not work - it either sits at 0 mph or bounces around near 100 mph! Initially, I had both grounds from the trans controller tied together with the TPS module and then to the battery. I spoke to US shift and they told me to ensure ground pin #15 is tied to the tps module (not grounded) and ground pin#16 goes to a ground within 1.5 ft of main EFI ECU ground. I made the changes and still have same problem. To be specific, pin 16 and the EFI (MSD atomic EFI) ECU main ground are on the same BUS bar (with all of my grounds) and the BUS is connected to neg batt post with 8 gauge wire.

To make things more confusing, I assumed the problem was due to a short in the actual controller because when the issue starts, if I move the wires that lead into the controller, the speedo begins to work correctly (but that means I have one hand on the wheel and one hand on the controller). US Shift does not think the problem is due to a short because, they said if it was a short, the problem would happen in every gear (not just top gear).

Anyone else have similar issue?

 

[Broncobowsher]

Can you tell (even if it means making a temporary software change) if it is tied to the convertor lock up?

This is one of those times where I really need to just dig out a lab scope. Since you are dealing with pulses, and ghost pulses. The signals coming out of the quick shift can be perfect, but if there are external influences you are chasing the wrong problem. It could be in the speedometer or a gound issue between the speedo and the controller.

 

[Jebus]

I have version 2 of this DSO Nano scope. V3 looks more capable.
Duty cycles, PWM, Frequency, Can Bus issues.
Seems some sort of scope is required in todays equipment world.

https://www.seeedstudio.com/DSO-Nano-v3.html

 

[mgb0302]

Broncobowsher and Jebus. You guys are talking way beyond my capabilities. I understand the what you are saying regarding pulses and what not but I don’t know how to diagnose that sort of stuff. My limits with electrical are power, ground, and continuity.

However, Kevin at US Shift did say to try and connect the speedo ground to the main ground wire of the controller and see if that works. Starting that project now. Will post update.

 

[Jebus]

Tracing that drop out can be done with a multimeter. A clean signal ground is certainly a possible culprit. I don't know how many solenoids that transmission controller has active in 3rd, but it also has to sink those coil drivers. Circuits have to be complete for stuff to work correctly.

 

[Broncobowsher]

3rd would be one shift solenoid, line pressure solenoid, and if locked up the torque convertor solenoid.
4th gear would add one more solenoid.

I don't know this latest version, but my very early version had 3 grounds. One for logic, and two for the solenoids. I thought both shift solenoids shared one ground and the lockup and line pressure the other.

Remember the line pressure draws more current at light throttle. Default is high line pressure and energizing the line pressure solenoid lowers the line pressure.