Diagnostic Functions

Diagnostic functions

General
The rear electronic module (REM) has a built-in diagnostic system, the Volvo on-board diagnostic (OBD) system, which continuously monitors itself and the input and output signals.

Diagnostic trouble codes (DTC)
A diagnostic trouble code (DTC) is stored if the rear electronic module (REM) detects a fault. This control module can store up to 6 diagnostic trouble codes (DTCs), the 3 first and the 3 latest.
Should a fault disappear for any reason after being permanently stored in the control module as a diagnostic trouble code (DTC), the information remains stored in the memory.

Reading and erasing diagnostic trouble codes (DTCs)
Stored diagnostic trouble codes (DTCs) can be read off and erased using this function. The on-board diagnostic (OBD) system can identify 58 different faults in the rear electronic module (REM) in the form of diagnostic trouble codes (DTCs).
This function can also be used to read off whether the fault is still present (permanent) or whether it has now ceased (intermittent) after the diagnostic trouble code (DTC) has been stored.
Diagnostic trouble codes (DTC) can only be erased once all the diagnostic trouble codes (DTC) have been read off at least once.

Reading off input and output signals
This function can be used to continuously read off the values and status of the rear electronic module (REM) input and output signals.
The following parameters can be read off:
- status of the locking relay and unlocking relay for the left rear door
- status of the locking relay and unlocking relay for the right rear door
- status of the relay for the rear folding head restraint
- the status of the trunk lid pop-up relay (4 doors)
- status of the locking relay and unlocking relay for the fuel tank filler cover
- status of the rear fog lamp relay
- status of the rear fog lamp relay, German version and trailer
- status of the back-up lamp relay
- status of the rear windshield heating relay
- power supply from the rear electronic module (REM)
- fuel level, left and right tank halves
- input signal from the pressure sensor (CNG), Full (200bar): 4.5V Empty (0 bar): 0.5V)
- input signal from the temperature sensor (CNG) (5V - 0.5V) (0°C~4.5V, 25°C~3.6V)
- lamp fault. Indicates whether any bulb has blown. Parking lamp groups 1 and 2, cover the left and right rear parking lamps.

Note! On early S80 models parking lamp groups 1 and 2 correspond to the inner and outer lamps.

- the power supply to the inclination sensor module (ISM) (low, high). High when the car is alarmed, otherwise low
- Inclination sensor module (ISM), alarm status. Indicates whether the inclination sensor module (ISM) has deployed the alarm
- Inclination sensor module (ISM), x/y status. Indicates whether the inclination sensor module (ISM) has deployed first in the X or Y axis
- the status of the trunk lid handle, (pop up, no action) (4 doors)
- current, bulb failure warning sensor group 1 (left rear parking lamps). The rear electronic module (REM) detects lamp faults when the current is below 0.6A (4 doors) / 0.45A (5 doors)
- current, bulb failure warning sensor group 2 (right rear parking lamps). The rear electronic module (REM) detects lamp faults when the current is below 0.6A (4 doors) / 0.45A (5 doors)
- current, lamp fault rear fog lamp. The rear electronic module (REM) detects lamp faults when the current is below 1.5A
- Central electronic module (CEM) driver brake (off, on). Checks the input signal from the stop lamp driver from the central electronic module (CEM) to the rear electronic module (REM)
- stop lamp check (lamp on, lamp off). Checks whether the rear electronic module (REM) transmits a signal to activate the stop lamp relay
- current, lamp fault, stop lamp. The rear electronic module (REM) detects lamp faults when the current is below 3.0 A
- status of back-up gear (idle, engaged)
- status of the relay for the tailgate wiper. Controls starting and stopping the tailgate wiper (5 doors)
- status of the relay for extended X-supply. Controls the power supply to the tailgate wiper (5 doors)
- status relay warming up diesel filter (Diesel)
- status relay 15I in the power supply
- status relay gas tank valve (Bi-fuel)
- status relay rear A/C (XC90)
- cargo compartment lighting output signal (0W - 10W)
- position sensor input signal for the headlamp beam height control (1.7V -3.2V)
- calibration status of the position sensor for headlamp beam height control
- status seat belt reminder passenger (off/on)
- input signal anode/cathode for seat belt reminder.

Activating components and functions
This function can be used to activate components and functions which affect the outputs on the rear electronic module (REM).
The following components can be activated:
- activation of relay, simultaneous rear locking (rear doors and filler cap).
- activating the relay, left rear door locking
- activating the relay, left rear door unlocking
- activating the relay, deadlock for the rear doors
- activating the relay, right rear door locking
- activating the relay, right rear door unlocking
- activating the relay, rear folding head restraint
- activating the relay, tailgate pop-up
- activating the relay, fuel tank filler cap locking
- activating the relay, fuel tank filler cap unlocking
- activating the relay, rear fog lamp
- activating the relay for the rear fog lamp, German version and trailer
- activating the relay, back-up (reversing) lamp
- activating the relay, rear windshield heating
- activating the relay, tailgate wiper (5 doors)
- activating the relay, extended X-supply
- activating the relay, warming up the diesel filter (Diesel)
- activating the relay, 15I power supply
- activating the relay, gas tank valve (CNG, Bi-fuel)
- activating the relay, rear A/C (XC90)
- set assumed fuel level in the left tank half (10, 20, 30 or 40 liters)
- set assumed fuel level in the right tank half (10, 20, 30 or 40 liters)
- set assumed information about bulb failure monitoring (lamp fault)
- activating and deactivating the inclination sensor module (ISM)
- check "sleep mode" ("wake up" or "enter sleep"), inclination sensor module (ISM)
- assumed signal from the handle, tailgate pop-up
- activate the rear electronic module (REM) alarm trigger
- activate the cargo compartment lighting
- activate the back-up (reversing) warning.

Reading off static data
With this function programmed data can be read off. For the rear electronic module (REM), this indicates primarily which relays should be installed.
The following statistics can be read off:
- relay, left rear door locking
- relay, left rear door unlocking
- relay, rear door deadlock
- relay, right rear door locking
- relay, right rear door unlocking
- relay, tailgate pop-up
- relay, fuel tank filler cap locking
- relay, fuel tank filler cap unlocking
- relay, rear fog lamp
- relay, rear fog lamp, German version and trailer
- relay, back-up (reversing) lamp
- relay, rear windshield heating
- relay, increased X-supply
- relay, tailgate wiper
- relay, folding rear head restraint
- relay, 15I power supply
- relay, rear air conditioning (A/C)
- relay, gas tank valve
- relay, RMI 15, reserve
- relay, RMI 11, reserve
- relay, RMI 12, reserve.

Reading off the control module identification
VIDA identifies control modules by reading off a number of codes from the control module memory.
The codes contain information about the control module:
- hardware P/N (control module without software)
- hardware serial number (control module without software)
- software P/N
- diagnostic software P/N
- P/N slave nodes (inclination sensor module (ISM))
- CAN frame period (40 ms for the CAN low-speed network at time of writing)
- Subcontractor identification plate (ECU-ID).