E38/T43 speedo output issue

[OldSkoolGP]

Been working on this issue with Tre Cool and run into a wall. Using OS 12639270 and TCM OS 24256125, we've got my VZ Crewman running and driving and everything on the cluster works apart from the speedo. Apparently the RepTOS pin on the T43 doesn't output data with the current OS, so the ECU has nothing to output as a RepTOS signal.

We both tried switching the VSS Sensor input and outputs to Serial and VehSerial, and that does make the factory speedo move, but only at 4/9ths the rate of the speed the transmission shows. No matter what values I change for the Pulses per rev, nothing changes. I even used VZClusterMod to change the pulses per KM in the cluster itself and that had no effect. I feel there must be a way to change the pulse rate when the output sensor is set to Serial, but I can't understand why changing the relevant values changes nothing.

[MPC001]

Been working on this issue with Tre Cool and run into a wall. Using OS 12639270 and TCM OS 24256125, we've got my VZ Crewman running and driving and everything on the cluster works apart from the speedo. Apparently the RepTOS pin on the T43 doesn't output data with the current OS, so the ECU has nothing to output as a RepTOS signal.

We both tried switching the VSS Sensor input and outputs to Serial and VehSerial, and that does make the factory speedo move, but only at 4/9ths the rate of the speed the transmission shows. No matter what values I change for the Pulses per rev, nothing changes. I even used VZClusterMod to change the pulses per KM in the cluster itself and that had no effect. I feel there must be a way to change the pulse rate when the output sensor is set to Serial, but I can't understand why changing the relevant values changes nothing.

Including the recent tune file as well.

Gotta love GM speedo setups

Congratulations for what you both achieved so far. Great projects. Crewman is standout in LHD.

[ironduke]

I can only assume when you change to serial there's other tables/switches involved for that.. You mind posting up the bin in question?

[OldSkoolGP]

I can only assume when you change to serial there's other tables/switches involved for that.. You mind posting up the bin in question?

Is an HPTuners file good enough? That's all I can pull from the TCM.

[ironduke]

Depends on the version you wrote it with but I can probably work with it.
Have you tried the speedo wizard in hpt yet to correct the 4/9 reading you did get?

[Tre-Cool]

i think i might have found the issue as to why the pulse feature doesn't work on the 24256125 os, If the binary address is correct, then im pretty sure the switch is turned off for the rearspdoutput as that is definitely different from the early vs late tcm code.

Description is similar to the ecu setup. "Indicates if the rear wheelspeed output, 128K PPM, is present on the vehicle."
24256125 on right, 24249179 on left.

EarlyvsLate-TCM-Speedo.png

Using a T76 a2l, the order of parameters is very similar as the late t43 cals, not perfect but when you look at the values they line up in a lot of area's. I suspect the newer code cleaned up a bunch of xref's though. Example:
24256125 on Left, 24237276 on Right.

EarlyvsLate-TCM-Speedo2.png

Going into the function block for the wheelspdserialdata, they are almost identical.

EarlyvsLate-TCM-Speedo3.png

I'll send u xdf in hpt to have a play, as it's time consuming to rewire my vy cluster to vz spec.

[Tre-Cool]

Just had a play in my VZ, turning off the Replicated TOS Output in TCM, stops my cluster from working.

The Rear Wheel Speed Output Speed did nothing.

REPTOS is not enabled in the later OS, so hopefully this will solve the issue of the Pulsed output not working.

[Tre-Cool]

Update for anyone interested. Turning on the Replicated TOS Output value in the later TCM code does in fact make the pulsed output work again.

Snapshot shows the address in TCM OS - 24256125

24256125-reptos.png

[MPC001]

Update for anyone interested. Turning on the Replicated TOS Output value in the later TCM code does in fact make the pulsed output work again.

So this routes the TOSS signal out of T43 to the hardwire feed to the VSS input on the E38? Replicating the VZ A4 routing.

[Tre-Cool]

Well the pin out of the gearbox is a Replicated (duplicated?) signal. But during testing on my vz I disconnected the pin from the ecu & it made no difference to the speedo from working.

It appears changing that value in the tcm must change how the frequency or pulse data is sent over the CAN.

*Update* It does make the wire work, Josh in the states confirmed it by unplugging the wire to the ecu & he had no speedo. Also made the speedo work on the e40/t43 combo.