Clutch wire troubleshooting.

[Jafro]

YouTube - Update + Jafro needs wiring help

The video contains everything. I have searched because my clutch wire IS connected correctly, and the clutch switch stays pegged on -1 in all conditions.

Info: I have a 3 year old problem that I can't seem to solve. Clutch wire failures are preventing me from using the clutch cut feature in DSMlink v2. I've wanted to use this feature ever since I installed it, but could never get it to recognize when the clutch pedal is pressed in. When I'm rolling on cruise control and I lightly touch the clutch pedal, the cruise control turns OFF... meaning the switch and cruise circuits work. When I enable clutch cut, the car won't rev past the point where I have clutch cut set. Initially, I had it on the wrong wire, but now I have triple-checked my connections and they're all correct. Even in this configuration, I can't read any change in the clutch switch position when I log that value.

I have tried:
Changing the polarity of the clutch switch wires - still reads the same.
Probing the switch for continuity and verified it works correctly.
checked the clutch switch harness and ECU for voltage.
Manually pressed the switch by hand, even further in than the pedal can at rest in case there's an actuation problem when it's mounted.
Searched on-line for anyone else having this problem and to no avail.

I'm stuck. Want to use no-lift-to-shift. Help.

Does the clutchSw value only change if you exceed the speed setting? I was always sitting still while testing it.

 

[luv2rallye]

I'm wondering why you're using ECU pin 91 since in my 99 factory wire diagrams that is the park/neutral position switch on a A/T. The clutch pedal position switch (one for the cruise with the black-red wire) goes to the Auto-Cruise ECU pin 1. Are our ECU's different for 2ga vs 2gb or could this perhaps be the problem?

 

[steve]

The park/neutral input is what you use for the clutch switch regardless of which switch you use, clutch safety or cruise.

clutchcutwire [ECMTuning - wiki]
cltchsw [ECMTuning - wiki]

The only thing I can think of off hand is somehow the diode in the wire from DSMLink is blown or backward. The diode keeps the cruise control and ECU functions from interacting.

Or perhaps the Enable clutch cut checkbox isn't selected.

 

[Jafro]

You know... I hadn't read anywhere that the enable clutch cut thing had to be checked before the logged value works... but I tried it sitting still in my driveway and it stayed on a straight- 1 with clutch in or out.

There's another setting for the mph at which the clutch cut begins working. It's at 7mph. I never set it to zero. Do ya think I have to satisfy the speed sensor setting before I see a difference in the logs? After all, I did all of this without ever driving it. I was just expecting to be able to log the value sitting still.

Also, I could have indeed blown up the diode. I had it wired in wrong for 3 years before it was wired correctly. Was previously on the MPI relay circuit which is a powered circuit. I guess figuring that out requires cutting the wire loose and probing continuity in 2 directions... but without knowing the direction of the DC flow, I really won't know exactly what I'm looking at.

 

[steve]

The switch grounds the signal, so conventional current flow is from the ECU to the switch or from the CC ECU to the switch. The diode would block and current flow from the CC ECU to the ECU. (band side to the switch)

Ask Tom and Dave on the Link forums to be sure.

 

[Jafro]

The switch grounds the signal, so conventional current flow is from the ECU to the switch or from the CC ECU to the switch. The diode would block and current flow from the CC ECU to the ECU. (band side to the switch)

Ask Tom and Dave on the Link forums to be sure.

I gotta say, DSMlink is probably the best-supported product these cars have ever seen.

In discussion regarding this issue, it was determined that I blew up my diode by previously wiring it incorrectly, causing a condition known as a floating pin. I have a temporary work-around that disables the cruise-kill circuit, and a new clutch wire is already on its way.

YouTube - Clutch wire work-around

For the first time I've experienced no-lift-to-shift, and I can't believe how much faster I can make the 1/2 shift now. This changes everything. I can't wait to get numbers at the track. That shift was taking over 1.2 seconds prior to this mod to clear the double-synchros. The hesitation is gone. Wow, just wow.

 

[steve]

I'm glad it was just the diode and glad that my reasoning isn't gone yet.