It is hard to tell what may be wrong not knowing any history.
Get VIDA or a better OBD code reader that reads all computer modules.
Check for codes. Do not throw parts at it. All of us here at Swede Speed will help to get this sorted out.
When the key is inserted, Antenna ring sends the key chip info to the CEM.
CEM sends info to the ECM. ECM sends signal back to the CEM, Start = OK, Start = Not OK.
CEM grounds starter relay 2/35 to turn on the starter.
With VIDA you can go in and see if the ECM is start OK, start Not OK.
With VIDA, go into CEM to see if key inserted is displayed.
You could have water damage in the CEM.
Look at Xemodex CEM remove instructions.
Remove wiper blades and hood cowl, wiper motor assembly to access top side of the CEM.
Remove CEM cover, top side connectors, inspect for water damage.
Last pic, reuse, reseal blue cover, inspect top side connectors.
Check out Xemodex.com, they car repair computer modules.
Lets hope that the ECM, CEM are both original.
If a used ECM, ECM was installed, it will not work. You will not be able to tell if a used one was installed.
Modules marry the CEM and can only be used for that combination or VIN.
Alarm system could be an issue. If the alarm thinks that the car was messed with or stolen, it can keep the
engine from starting. Read all codes and report back.
Xemodex Inc Technology Improved United States | 1-888-712-2525
Central Electronic Module Program Transfer for Volvo P2 Platform | XeMODeX Inc.
CEM Removal Instructions Video for 2005-2013 S60, S80, V70, XC70, XC90 | XeMODeX Inc.
ECM-7100 Immobilizer communication. Faulty signal, B5254T2
ECM-710B Immobilizer communication. Signal missing, B5254T2
CEM-3F81 Immobilizer signal. Signal too high, B5254T2
CEM-3F82 Immobilizer signal. Signal too low, B5254T2
CEM-3F83 Immobilizer signal. Signal too low
CEM-3F84 Immobilizer signal. Faulty signal
284: ECM-7100 Immobilizer communication. Faulty signal, B5254T2
Faulty signal. Permanent fault
Information
This diagnostic trouble code (DTC) indicates that the immobilizer code does not match between the engine control module (ECM) and the central electronic module (CEM). This may be because:
the immobilizer code in the engine control module (ECM) is incorrect i.e. the code does not correspond to the code stored in the central electronic module (CEM)
the engine control module (ECM) is not programmed and has no immobilizer code
the immobilizer code in the central electronic module (CEM) is incorrect
the central electronic module (CEM) is not programmed and has no immobilizer code
the engine control module (ECM) is damaged
the central electronic module (CEM) is damaged.
Note! A programmed engine control module (ECM) or central electronic module (CEM) cannot be moved from one vehicle to another.
Hint: Read off the diagnostic trouble codes (DTCs) for the central electronic module (CEM).
For further information about this diagnostic trouble code (DTC), select Information, then DTC information.
Other information:
To access and replace the engine control module (ECM), see Engine control module (ECM), replacing
To access or replace the central electronic module (CEM), see Central electronic module (CEM), replacing
For information about signals on 5-cylinder engines, see Signal specification
For information about signals on 6-cylinder engines, see Signal specification .
284: ECM-710B Immobilizer communication. Signal missing, B5254T2
Signal missing. Permanent fault
Checking the component
The immobilizer function is integrated in the central electronic module (CEM).
This diagnostic trouble code (DTC) can be caused by missing CAN communication. If there is a diagnostic trouble code (DTC) stored in the central electronic module (CEM) fault trace accordingly.
If no diagnostic trouble codes (DTCs) are stored in the central electronic module (CEM), try a new central electronic module (CEM).
Other information:
To access or replace the central electronic module (CEM), see Central electronic module (CEM), replacing
To access and replace the engine control module (ECM), see Engine control module (ECM), replacing
For signal specifications for the central electronic module (CEM), see Signal specification
For information about signals on 5-cylinder engines, see Signal specification
For information about signals on 6-cylinder engines, see Signal specification .
Xemodex Inc Technology Improved United States | 1-888-712-2525
Central Electronic Module Program Transfer for Volvo P2 Platform | XeMODeX Inc.
