It is a Blazer 89 with a LSX454 and a build 4L65E. Just completed the build, engine is running fine and we can put it in "Drive" and drive the car but in 1 gear only. It does NOT shift up or down. Oil level on the trans is confirmed OK but it seems that the TCU does not get a speed signal from the ECU.
We run the GM 19354342 - Stand Alone Harness for the LSX454 and the GM 19302405 - Stand Alone Harness for the 4L65E.
The blazer is a 4x4 and the speed signal is picked up by a Dakota Digital SEN 01-1 (8K pulses) from the transfer case via the analog output. The signal is fed in to the 19354342 ECU via the "vehicle speed" connection/port as per the drawing.
The ECU has been programmed to match the 8K signal from the ECU.
We run a Dakota HDX gauge and the gauge is fed from the ECU via the speed out (not the Canbus but the speed out please see attached harness schematic) so we know the speed signal is there as the gauge shows the correct value.
We have checked with the HPTuners VCM Scanner tool we can't see the drive shaft speed.
We have use the manual shift function and we can get the trans to shift manually.
Gear ration has been inserted. Wheel size has been inserted.
The trans plug is the green/gray type.
The TISS plug on the TCU harness is not uses on the 4L65E. The TISS is only used on 4L80E.
This is teh settings we have in the ECM/TCU:
Sorensen Tune Comparison Log ? this comparison shows any fields that were changed from the original information in the ECM to current.
1. Tach Output ? When we make a harness Stand Alone we change this field from CRANK to FREQUENCY to make it work with an aftermarket tachometer
2. Injector Flow Rate vs. Pressure Delta ? This is where the injector size is set.
3. Master DTC List ? We ?checked? the boxes for Electric Fan control to ?turn on? this option
4. ECM Transmission Type ? The ECM default setting is for a manual transmission. It was changed to MANUAL to AUTO
5. Fan Desired % vs. ECT ? Electric Fan Control Setting
6. VSS Pulses Per Rev ? We changed from 40 PPR to 4 PPR
The only item in this list that has anything to do with VSS is #6 which we have discussed extensively.
These next two fields are on the same screen and may have something to do with the speed signal.
* Speed Output Type Setting Choices ? Can be set to WheelSpd, VehSerial or VehRep TOS. Your ECM was set to VehSerial.
** Vehicle Speed Output Setting Choices ? Can be set to Disabled, RepTOS or Seial. Your ECM was set to RepTOS.
We left these settings as they were in the ECM, but they do not match the settings we commonly see, however we find these settings to be inconsistent in other ECMs so we don?t know what the ?perfect? choices are. It may be worth changing them to see if it changes what the TCM sees for data.
Let me know if I am missing out on information to make it more clear, any help or comments is much appreciated.
Thanks guys.
Best regards
Jacob Sorensen
Last edited by Jacob Sorensen; 06-10-2020 at 11:50 PM.
Jacob, the mention of the VSS rang a bell with me. The 4L65E is the transmission behind the LK5 in my CJ. The notes in my manual caution that the speed sensor leads must be a twisted pair with a minimum ten turns per foot and shielded if that was their original makeup. The note mentions component damage or degrading of performance. The only other note is for 1420 ohm resistance at 77F for the VSS and greater than 10M ohms to ground.
This info is from the 2006 GM service manual.
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