6L80 LS1 PCS TCM2650 random pattern switching and harsh 4-5 and 5-6

[Lumina VX]

And so the saga continues......!

My tuner managed to write a new tune to the trans via the seperate DLC which is part of the PCS kit. This got rid of the delayed shift/ flare on the 4 to 5 shift on light to medium throttle, but we then started experiencing a new problem - a harsh shift from 5-6 on anything over 30% throttle. Occasionally, this harsh shift would be felt on the 4-5 shift too, which is exactly what it would do on the old tune. All other shifts up and down are fine and the trans works fine in true manual mode. Driving home that day, I could feel the trans playing up in 6th at cruising speeds, although the gear indicator stayed mostly steady showing 6th, whereas previously it would flicker from 5-6-5 or 4-5-4 unless in manual mode.

We noticed whilst logging on HPT that the trans is randomly changing from normal to pattern A. This can happen at any throttle opening and in any gear, but you can only feel it causing an issue in 4,5,6. The original Holden Commodore Power button by the gear selector has been reconfigured to switch the trans to manual mode via the PCS TCM2650, so I disabled all the digital inputs on the PCS software, to take this out of the equation, just in case. It made no difference.

My tuner then made normal and pattern A data the same, but again, no difference to the shifts. It would seem that the switching patterns is in sync with the flickering gear number on my display/ HP Tuners log and in the PCS software.

In the HPT log, you'll see the harsh shift from 5 to 6 about halfway in, just look for the highest speed peak.

I'll send these files to Jim at ZGP too. Thanks in advance for your help.

https://1drv.ms/u/s!AvYJGSX0WE3IkFnc...Oqlfx?e=gBsJSD

gearbox tune oem v3.hpt

2023-03-15-Wednesday_at_AM-10-41-02-w-Dig Inputs correct and adjusted shift table A and tapshift.bin

gear 1.hpl

[Ben Charles]

I’ll check this out for you later and give you some input

[Lumina VX]

Thank you, once again!

Jim has replied, to point out I have 'TPS and RPM enabled for both CAN and analog'. Which creates a conflict in the TCM2650 module. He's asked how I'm getting TPS and RPM and I've replied to say both are via analog. TPS is connected to the TCM2650 at pin 45 and the tacho signal is connected at pin 24.

I've asked him if I should therefore deselect 'Receive TPS' and 'Receive Engine RPM' in the CAN input selection box on the PCS software, leaving CAN to just receive Vehicle Speed and Range Selection.

I have nothing ticked in the main CAN selections box.

Hope this isn't too confusing?!

[Ben Charles]

I looked at the tune file, its using an early 6L80E OS from what it appears which mostly looks stock to me. IF I get a moment i'm going to do you a freebie and see how it feels.

[Lumina VX]

Jim has replied to confirm I should un check TPS, Load and RPM on the CAN input selection. This is weird, because I don't recall changing any of this since the last time Jim checked it over for me! Anyway...I'll do it and try and test drive this weekend.

Thank you Ben, I appreciate your offer, but I don't have the HP Tuners dongle for the DLC, just the HP Tuners software on my laptop. I understand there is a way round this though?

[Lumina VX]

Quick update; test drive showed no positive changes to the trans operation, but instead I now have the trans mostly skipping 3rd gear on the upshifts. It was also coming to a stop at junctions in 5th gear. Manual operation is absolutely as it was, so no problems there. I loaded a few of the older calibration files into the TCM2650, but the skip shift is still present.

The speedometer only works up to 20mph, then falls to zero. It will work pretty well (albeit with fluctuations) up to 50/60mph, but only if I'm online with laptop connected to the PCS software.