Dash cluster gauges don’t don’t work

[Ross]

I also have this dash gauges issue on my 2006 SC LSJ.
My gauges on the dash are intermittent. They turn on about 2% of the time, mostly when the engine is off. Vibration issue?

So I probed the wires going to the dash cluster:

Pin 2 - goes to ground when the button is pressed.
Pin 6 - It is 0V as my check engine light is off.
Pin 8 - PWM signal that changes based on the dash brightness knob.
Pin 9 - I am getting data packets on this. There is a fair amount of data, and I don't have a data logger or sniffer, but I can take a screen shot on my oscilloscope and see data packets. Guess I could decipher some packets manually.
Pin 10 - goes to ground when the button is pressed.
Pin 11 - goes to 12V when key is on
Pin 13 - 12V+
Pin 14 - normally 0V, but goes to 0.67V for 3 seconds after key is turned on
Pin 15 & 16 - 0V ground.

I have tried 2 dash clusters, and 2 BCMs, but the problem persists.
Today I drove the car with the oscilloscope on the GM Low Speed LAN wires, but the data packets are still flowing when the gauge issue occurs.

I have voltage probed the dash wire connector with the gauges working, and not working.
Not really sure where to go from here.
I have ordered parts so I can do data sniffing on the GM Low Speed LAN, but that will be a while.
I need specs on what the GM data packets mean, so I know which ones are for the gauges.

Probably be faster just to do visual wiring inspections everywhere... wish I had better method.

 

[Ross]

Dale E threw some ideas at me. Got me thinking.
This intermittent issue has been going on for a few months now...
I wiggled wires for the first month, then I gave up on it. Probably is a bad connection somewhere, or a wire shorting.
Since it was running correctly for the first year, I don't think it is wired wrong.

Lately I have had an intermittent ignition starter issue. Maybe if I fix that, the dash gauge issue might be fixed too.

 

[Anks329]

My obd2 reader is showing my mph, next test will build out a better dash on the tablet I’m testing with. I’m thinking of entirely replacing the gauges with an electronic tablet based dash instead.

 

[Anks329]

I also have this dash gauges issue on my 2006 SC LSJ.
My gauges on the dash are intermittent. They turn on about 2% of the time, mostly when the engine is off. Vibration issue?

View attachment 15758

So I probed the wires going to the dash cluster:

View attachment 15760
Pin 2 - goes to ground when the button is pressed.
Pin 6 - It is 0V as my check engine light is off.
Pin 8 - PWM signal that changes based on the dash brightness knob.
Pin 9 - I am getting data packets on this. There is a fair amount of data, and I don't have a data logger or sniffer, but I can take a screen shot on my oscilloscope and see data packets. Guess I could decipher some packets manually.
Pin 10 - goes to ground when the button is pressed.
Pin 11 - goes to 12V when key is on
Pin 13 - 12V+
Pin 14 - normally 0V, but goes to 0.67V for 3 seconds after key is turned on
Pin 15 & 16 - 0V ground.

I have tried 2 dash clusters, and 2 BCMs, but the problem persists.
Today I drove the car with the oscilloscope on the GM Low Speed LAN wires, but the data packets are still flowing when the gauge issue occurs.

I have voltage probed the dash wire connector with the gauges working, and not working.
Not really sure where to go from here.
I have ordered parts so I can do data sniffing on the GM Low Speed LAN, but that will be a while.
I need specs on what the GM data packets mean, so I know which ones are for the gauges.

Probably be faster just to do visual wiring inspections everywhere... wish I had better method.

Where did you get the detailed table with all the pins? I've got access to Chilton's library, and found the overall wiring diagram, but don't see this kind of table in it. I've got a '07 base, and don't think the wiring is the same as yours.

 

[Ross]

Try here, but it might be some changes for your year.