Having issues with my “lab” can someone help me try to sort this out that has done it before?
I have the BCM for a ~2002 chevy s10 blazer I am trying to hook up. J1850 protocol
I have the ODBII connector, the BCM and the dash cluster hooked up.
For both I have the ignition leads (1 & 3) hooked up to constant 12v. One of the ignitions is for run/accessories and the other is active run/accessories/start
The cluster lights up with some alarm lights lit up but I am not getting any data from the ODBII port. Using a standard ODBII to USB cable.
Not aware that I need any sort of termination but I am not sure which databus I need to connect to on the BCM.
From the service manual it appears that the “Diagnostic” databus is supposed to be the main databus and is connected to all devices. There is another one just labeled databus which appears to be a secondary one to the PCM. (The PCM also has one to the diagnostic databus). There is a third databus on the BCM that says it is a “Secondary” databus and does not show where it is connected when I looked in the service manual.
At this point I am not sure if I am grabbing the wrong bus, if the ignition feeds don’t need to both be on or what I am doing wrong?
I have hooked up any ground on both the cluster or the BCM directly to my ground. Both of the ignition leads from either the BCM or cluster are connected to +12v with the +12v wires and as already mentioned the databus from the BCM to diagnostic is attached to the connector and the cluster.
When I connect my unit to the connector it can not connect.
Note that it connects fine to my '03 Avalanche which uses a much different BCM but still J1850.
Rodney