Class II data and Instrument cluster

[albj93]

Hello everyone,

Asking for some help on a on an '06 Silverado duramax but I don't think it's diesel related..It started after sitting for ~3 months rebuilding and replacing the motor from broken crank. It has this problem where the oil pressure, water temperature, fuel level, trans temperature, Driver information center and PRNDM gauges/indicators don't work. Also, the battery red indicator is always on when the truck is running or in the key on position. When its running the charge is fine at ~13.4-14.2 volts depending on load..

I swapped the dash cluster from the '06 into my 2003 Tahoe and it all worked perfectly. Installed the 2003 Tahoe cluster in the '06 and it did the same thing so I assume it's not the cluster.

I am also fighting a class II communication fault in the PCM, BCM, Instrument cluster and just about all of the other modules in this truck. Codes are U1000 and U1300(Class II fault and Communication).
It appears that all of the devices mentioned for the instrument cluster get their information/status from the class II data line. What I am not sure of is how the cluster processes it. If you read the data stream from the PCM with a scan tool(I use a Solus pro and Auto Enginuity), the gauge information is there i.e. oil pressure psi/volts, fuel level/volts and water temp and can be displayed on the scan tools...If you read the instrument cluster displayed data for these gauges/indicators with a scan tool it is a zero...
I have also swapped the BCM with the Tahoe for testing and was able to clear all of the class II communication errors from all of the modules but it didn't make the cluster work.. It did cause some other issues but they were from the BCM swap i.e. airbag module codes(doesn't recognize the BCM) and Passlock issues(no re-learn code from the ignition key. This truck has EFI live on it so the passlock re-learn has been written out of the code or else the truck wouldn't start with the BCM swap without the key relearn procedure). Swapped the BCM back into the Tahoe, 30 minute key learn process and Tahoe is well...
I have also pulled apart connector SP205 which is the shorting connector that ties all of the modules on the class II network together. It is located above the emergency brake pedal. With this connector opened, all of the modules are isolated from one another. In my troubleshooting I just had the PCM, BCM, Instrument cluster module and theData like connector jumped/tied together with nothing else on the network. I did this thinking that one of the other modules could be shorting out the class II data line. Ran the truck but no change in the instrument cluster.
I am also having A/C clutch issues. The the A/C module data shows the water temp at 266 degrees thus denying the compressor run status...PCM data shows the water temp at 170 degrees...I can command the relay on with the scan tool and everything works as designed.
At this point I am at replacing the BCM for the class II data malfunctions. The PCM possibly causing all of these problems with the gauges/indicators but not ready to make the plunge yet for replacement as I am not understanding why the values can be in the data stream and displayed on the scan tools but not displayed in the instrument cluster and the A/C water temperature values being wrong..

I searched through the site but had no solutions..I posted in another forum also..Just looking to see if anyone has run into this before as this is the worst problem that I have had to repair out of all of the trucks.....

Thank you for your time and reading this.
Andy
Waldorf MD

[albj93]

Hello everyone,

Just as a follow-up. I enjoy reading here and one other forum so I thought I would post my solution.

I replaced the Powertrain control module and the Body control module everything is working except the PRNDL indicator and the seat memory. The selected gear status on the scan tool is ???? which leads me to believe that the Allison trans gear selector is not working or the TCM is malfunctioning although the trans works well. The seat memory is probably related as the module is not getting the park indication form the TCM/selector.

If anyone cares....

Thanks,

Andy

Waldorf MD