Unique Characteristics Motronic 4.3 and 4.4
The VST does not provide continuously updated online updates of the diagnostic status. To check the status of readiness before, during or after a drive cycle, exit and re-enter the VST function. The screen will then be updated.
Turn air conditioning off during all stopped or idle periods, as the A/C load may cause a diagnosis to be interrupted. This will require more driving to get that diagnosis to run again.
Using the VST, it can be determined if all diagnostic functions were completed. To do so, enter the VST 'DIAGNOSTIC CHECK' menu. At the 'TRIP/READINESS' screen press enter to display the status of the DTC's that still need to be tested on the current trip. Refer to page 3 for the specific instructions on how get individual diagnostics to run.
Motronic 4.3
Flywheel adaptation needs to be "ready" before a trip can be completed, on Motronic 4.3 the VST cannot read the flywheel adaptation status, therefore we should assume the adaptations are not set and follow the flywheel adaptation procedure on page 4 before continuing with the first trip.
When interrogated using a generic OBD II scan tool the MY 1996 Volvo 850 equipped with Bosch Motronic 4.3 Engine Management System, may experience all of the
Readiness Codes changing from 'COMPLETE' to 'INCOMPLETE' when the ignition key is cycled. This behavior applies to all 1996 M 4.3 850's and cannot be corrected. DO NOT turn the engine off until after the Enhanced Inspection/Maintenance OBD II check has been completed.
Readiness status cannot be read from a vehicle equipped with Motronic 4.3 using the VST, but the completion of two 'TRIPS' will establish readiness.
MY 96 850 non-turbo: Run first test as described. Prior to running second trip activate SAS and Leakage diagnostic test. The second trip can be started with the engine at operating temperature. The coolant temperature can be read out from the 'SCROLL LIST' using the VST.
Motronic 4.4
Flywheel adaptation needs to be 'READY' before a trip can be completed. Establish flywheel adaptation at beginning of first trip following instructions on page 4, and then continue with Trip.
- Engine temperature at start must be between +29°C (84°F) +49°C (122°F). If engine temperature is below +29°C, start engine to warm up over +29°C and then shut off. Restart engine when coolant temperature is between +29°C and +49°C.
- Start engine, go directly from position 2 to position 3 do not cycle key. The EFI 112 status should then change from 'NOT TESTED' to 'TESTED'. This indicates that the ECU has seen the correct start criteria.
- Another confirmation that the ECU has seen the correct start criteria is to access the EFI code 112 in the 'DIAGNOSTIC CHECK' menu. With ignition key in pos. 2, engine off, access the 'DIAGNOSTIC CHECK' menu and press enter. The EFI codes will appear. Scroll down until you get to EFI 112.
- 'READINESS=YES or NO' can be read using the diagnostic function in the VST. 'YES' requiring the successful completion of two trips.
- 960 / S/V 90 - It is not possible to complete the test for code 211. Code 211 is not valid for this market. The trip is completed when 'substitute trip' is displayed and the only code remaining is 211. Using the monitor test confirm that a trip has set by 'TRIP=YES'.