M13dolphan wrote:
So maybe I should start disconnecting sensors like oil pressure and those that run through the FCM and see if there is a shorted sensor killing communication? Is there a specific fuse that could disrupt instrument cluster communication? It seems to me that if it were a bad FCM or a problem with the ECU the engine wouldn’t start at all.
Where are you located, you don't have a signature listed?Pulling fuses is not a surefire way of eliminating a bad sensor or wiring issue; only by disconnecting each sensor one at a time can you identify a faulty sensor.
But if it is a wiring issue, disconnecting sensors will be of no help in identifying a wiring short.
A good scanner could help tell you which communication circuit or module is down and then you could look at the wiring diagrams and see what sensors are connected to the bad circuit or module.
To properly diagnose a communication problem with the Can Bus, you need an oscilloscope to see where the problem lies.
See this:> https://www.vehicleservicepros.com/serv ... techniques
What can pull the communication (Can Bus) down and make it inoperative:
- 1. short to ground of any of the communication circuits (wires) going to or from the FCM.
2. any of the sensors that are connected to the FCM shorts to ground internally or if their sensor wire going to the FCM touches a ground or shorts to another wire in the wiring harness.
3. a bad module or the FCM itself.
There is also another ground under the rubber flap on the firewall above the brake booster that should be checked along with the others already mentioned.
