07-16-2019, 08:18 AM
WF Supporting Member
Join Date: Jun 2013
Location: Glendora, Ca
Thank you I will try those.
Originally Posted by skjeep1
there is nothig like " Lost communication with the Can Bus"
CanBus is a kind of network. It does not communicate. It provides the communication. You have to understand it as kind of wire or pipeline the data flows thru.
Generally loss of comm is hard to diagnose with aftermarket scanners. The best to go is OEM WiTech or (for 2007JK) the older Starscan.
There are several CAN networks in JK.
Powertrain CAN - for engine management and all the important powertrain data
Interior CAN - for body, radio, HVAC, restraints .....
Diagnostic CAN - for diag purposes
plus there is also a one wire LIN bus network - for switches, turn signals, wipers
Not all control units are connected to all networks. In JK only the TIPM and ORC are connected to both powertrain and interior CAN. Where TIPM acts as a gateway between all network nodes.
Actually the B2100 is for Ignition Run/Start Input Circuit Performance
If the TIPM detects that the CAN bus message and the hardwired ignition circuit do not match, it will set this error.
To understand - your ignition switch is not a simple on/off wired directly to some 12volt. It is a double safety . So there is one wire which shows 12V with ignition on and it goes only to TIPM. There is also another wire fed with 5 volts and variable MUX output. This goes from ign switch to the SKIM module.
Monitoring the voltage drop, the SKIM module sees the key position (lock, acc, ign, start) and populates this info on the CAN bus. The TIPM listens to that info and turns the other modules and drivers accordingly.
So long story short - if you turn your key to start positin (to crank the engine) you do not connect any wire to starter or relay.
The only thing what happens is, that ign switch sends a message (voltage drop) to SKIM. SKIM determines what the message is, send a data word thru Can bus network to TIPM. TIPM asks the PCM (and possibly other control units) if the start conditions (sensors, park neutral switch, VIN, voltage and dozen other things) are met. If yes, then the TIPM switches on the starter relay
Besides that it also checks for a valid key and matching VIN. But that is another story
So i would start with an OEM diagnostic tool to look for loss of comm errors.
Then i would check the wiring under steering wheel shroud. Was the clockspring allready replaced? Then i would remove both airbag fuses (teh onesin TIPM within yellow snap.