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Home >> Volvo >> 2000 >> C70 Convertible L5-2.3L Turbo VIN 53 B5234T3 >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> Manufacturer Code Charts >> ECM Codes (Engine Control Module) >> ECM-901A >> Communication Control Module, Communication Problems. Faulty Signal. Permanent Fault >> Too High Signal/Signal Missing/Too Low Signal. >> Part 1

Part 1






Too high signal/signal missing/too low signal.






Frozen values and counter for diagnostic trouble codes.

Use the diagnostic trouble codes' frozen values as well as the counters, to determine the driving conditions when the problem was detected the first time and how often the problem has occurred. The values show the problem's current status and how intermittent the problem is. Driving conditions may be, e.g., if the engine was running, what speed the vehicle had, or how long the driving distance was.

Counter
The counters are used to determine the problem's status. For general information about the counters, see: Counters, description Counters, Description
Counter 1 indicates the number of drive cycles without fault since the fault was last validated.
If counter 1 is the same as 0, this means that the fault has been detected in this operating cycle (permanent fault). If no troubleshooting or repair has been performed in the vehicle in this driving cycle, the problem is probably in the vehicle.
If counter 1 is over 0, this indicates that the problem has not been detected in this driving cycle (intermittent problem). The problem has existed earlier but is not active right now.
Then check counter 4. Counter 4 indicates number of driving cycles with problem since the problem was validated for the first time.
If the number of driving cycles with problems is high, this indicates an intermittent recurring problem, which means greater possibility of regenerating the problem in the workshop.
If the number of driving cycles with problems is low, this indicates an intermittent temporary problem, which means small possibility of regenerating the problem.

Hint: Counter 3 indicates number of driving cycles since first time that the problem occurred. If the value for counter 3 is divided by the value for counter 4 , the intensity of the problem is obtained. The higher the value, the higher the problem intensity. A high problem intensity indicates that the malfunction recurs often.

Counter 5 can be used for more exact determination of when the problem occurred. To compare counter 5 for diagnostic trouble codes indicates in which order the diagnostic trouble codes were stored.

5-cyl. non-turbo engines
For model year 1999, only counter 1 and 2 are available.

Frozen values
The frozen values show the driving conditions when the control module detected the problem the first time. Check using the frozen values that the diagnostic trouble code has not been caused accidentally during troubleshooting of the vehicle. If the driving distance is 0 km/miles, this indicates that the problem has occurred at the control modules' start-up of the CAN-net, when reception of a relevant value has not been possible. This also applies to other values that come via the CAN-network. In these cases, counter 5 can be used to determine when the problem was generated.
If the diagnostic trouble code has been caused during this troubleshooting, it may be due to, e.g., disconnected component, too low or high battery voltage, or that some control module has been disconnected.
If the diagnostic trouble code has been stored since before, there has likely been a problem or interference, which has resulted in the control module detecting a problem.
For general information about frozen value, see: Information Information
For information about frozen values.
- Turbo engines and 6-cyl. non-turbo engines: Description of frozen values Me7 Description of Frozen Values ME7
- 5-cyl. non-turbo engines: Frozen values DENSO, description Description of Frozen Values DENSO
Read off the diagnostic trouble code's counter and frozen values by clicking on the symbol for VCT2000. Choose diagnostic trouble code in question.










Continue - DONE

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DONE - Checking the wiring and components

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Checking the wiring and components
Electronic throttle module (ETM) or Engine control module (ECM) does not work especially well together with CAN-high speed net. The two control modules monitor the CAN-high speed net continuously and are very sensitive to interference on the network. The two control modules will generate diagnostic trouble codes very quickly, if they detect problems on the network and will then reconfigure the system so that it is still possible to drive the vehicle, but then with reduced functionality. If Engine control module (ECM) or Electronic throttle module (ETM) detects a problem on the CAN-bus, this does not indicate that they have caused the interference. Most probable is that, since these control modules are the most sensitive on the CAN-high speed net, they will then also be the first that generate diagnostic trouble code when there is interference on on the CAN-net.
As the information states, many of the CAN- and throttle module-related diagnostic trouble codes can be generated due to communication in the CAN-network has been interfered with or interrupted for some reason. Thus, the reconfiguration that takes place does not indicate the cause. Therefore, troubleshoot diagnostic trouble codes for the CAN-net first in all control modules, using troubleshooting for these.

S60/V70 (00-)/V70 XC (01-)/S80 (-06)

Hint: If there are diagnostic trouble codes stored in central electronic module (CEM) that indicate incorrect communication in CAN-high speed net, troubleshoot according to these before the following troubleshooting is performed. If there are stored diagnostic trouble codes, this indicates that the problem has existed for a longer time, more than 5 seconds. However, if no diagnostic trouble codes are stored, then this indicates that the problem is of a brief nature, shorter time than 5 seconds, likely caused by very brief interference, open circuit or short-circuiting in leads or connections.

S70/C70/V70 (-00)/V70 XC (-00)

Hint: If there are diagnostic trouble codes stored in Driver information module (DIM) that indicate incorrect communication in CAN-high speed net, troubleshoot according to these before the following troubleshooting is performed. If there are stored diagnostic trouble codes, this indicates that the problem has existed for a longer time, more than 5 seconds. However, if no diagnostic trouble codes are stored, then this indicates that the problem is of a brief nature, shorter time than 5 seconds, likely caused by very brief interference, open circuit or short-circuiting in leads or connections.

If the VIDA-station with VCT2000 (Volvo Communication Tool 2000) is connected to the vehicle when the battery voltage is low, this may generate diagnostic trouble codes. VCT2000 receives voltage feed from the vehicle, and thus both VCT2000 and control modules can be interfered with and themselves generate interference when their feed voltages are low, (especially when trying to start and the battery is poorly charged). In certain cases, for troubleshooting of a CAN-related diagnostic trouble code, verify using counter and frozen values that the diagnostic trouble code is relevant and not stored during the time in the workshop.
Diagnostic trouble codes generated during troubleshooting can be identified using the frozen values and counters that are stored together with the diagnostic trouble code. Primarily driving distance is to be used to decide if the diagnostic trouble code is generated in the workshop or not. Compare the driving distance in frozen values with the driving distance in driver information module (DIM). If these do not differ too much, it is likely that the diagnostic trouble code was generated during the time that the vehicle was in the workshop. If the driving distance is 0 km/miles, this indicates that the problem has occurred at the control modules' start-up, when a correct driving distance not yet has been received from central electronic module (CEM) or Driver information module (DIM). In these cases, counter 5 can be used to determine when the problem was generated. This prevents fault-tracing an irrelevant code. The risk with too low system voltage in the vehicle can be minimized using a battery charger. In this way voltage is kept stable, if troubleshooting goes on for an extended period of time.

Note! Only use battery chargers that have been approved by Volvo, since too high voltages can cause problems and generate diagnostic trouble codes in the vehicle.

- Check the connector on the electronic throttle module (ETM). Check for contact resistance and oxidation. In particular, check terminals #3 (CAN H) and #4 (CAN L), #5 (ground) and #6 (voltage).
- Check the connector on the engine control module (ECM). Check for contact resistance and oxidation. In particular check terminals #A37 (#A37) (CAN H) and #A55 (#A55) (CAN L). In particular, check the wiring, pins and terminals for damage. Check that they are properly inserted into the connector. Check that the cable is properly connected to the pin or terminal.
- Check the CAN H cable between electronic throttle module (ETM) terminal #3 and engine control module (ECM) #A37 (#A37). Check for an open-circuit. Check for a short-circuit to ground. Check for a short-circuit to supply voltage.
- Check the CAN L cable between electronic throttle module (ETM) terminal #4 and engine control module (ECM) #A55 (#A55). Check for an open-circuit. Check for a short-circuit to ground. Check for a short-circuit to supply voltage.
- Check the voltage supply cable between electronic throttle module (ETM) terminal #6 and system relay terminal #3 (87). Check for an open-circuit.

Hint: With the ignition on, the voltage must be approximately battery voltage between electronic throttle module (ETM) terminal #6 and ground.

- Check the ground lead between electronic throttle module (ETM) terminal #5 and the car body. Check for an open-circuit. Check for a short-circuit to supply voltage.
If no fault is detected in the above fault-tracing, the fault may be because there was a delay before the system relay switched on. This delay may be due to low battery voltage and/or a mechanical fault in the system relay.

Hint: For markets where upgraded software, released during year 2006 or later, is available, the solution may be to download the upgraded software. In the upgraded software certain adjustments have been made to make it more tolerant against brief CAN-interference. See conditions for respective diagnostic trouble code, for more detailed information about what adjustments have been performed.

Remedy as necessary.

Other information:
- Checking wiring and terminals Checking Wiring and Terminals
- To access or replace the system relay, see the location of components

Caution! In order for Electronic throttle module (ETM) to reset any reconfigurations as well as delete internally stored problems, the following must be performed:
- Ignition off, wait three minutes so that the main relay / system relay releases the voltage feed to, among other, Electronic throttle module (ETM).
- Then turn on the ignition and turn it off again.
- Wait another three minutes. If the electric cooling fan is running, you have to wait another two minutes after the electric cooling fan has stopped, to make sure that Electronic throttle module (ETM) has been shut off correctly.
If this is not done correctly, diagnostic trouble codes may remain even after deletion of diagnostic trouble codes as well as any reconfiguration, despite the problem being fixed.

Choose No to troubleshoot the whole CAN-net.

Note! Then, the information shown to the CAN-high speed net is adapted for S60/V70 (00-)/V70 XC(01-)/S80 (-06), but also applies in applicable parts for S70/C70/V70 (-00)/V70 XC.





Was a fault detected?

Yes - FAULT FOUND

No - Faulty communication

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