Checking components
Check if other control modules have diagnostic trouble codes (DTCs) for control area network (CAN) faults. If so, perform all troubleshooting acc. to these diagnostic trouble codes first. Otherwise, continue as follows.
ECM-928C is stored if the engine control module (ECM) does not receive steering wheel module (SWM) information on the cruise control buttons via the CAN network. The diagnostic trouble code is also generated if the information received by the engine control module (ECM) does not match that sent by the steering wheel module (SWM).
- Using VIDA vehicle communication, check that the parameters "Cruise control resume", "Cruise control SET-" and "Cruise control SET+" indicate the correct values. If the buttons work and the information can be read out in the engine control module (ECM), the fault is intermittent. Otherwise the fault is permanent.
Permanent fault
Check whether the steering wheel module (SWM) has stored any diagnostic trouble codes that indicate a fault in the cruise control buttons. Any diagnostic trouble codes that are stored should be fault traced first.
Check whether any other control modules have stored diagnostic trouble codes that indicate that the steering wheel module (SWM) was not transmitting on the CAN network. Any diagnostic trouble codes that are stored should be fault traced first.
Intermittent fault
Check whether the steering wheel module (SWM) has stored any diagnostic trouble codes that indicate a fault in the cruise control buttons. Any diagnostic trouble codes that are stored should be fault traced first.
Check whether any other control modules have stored diagnostic trouble codes that indicate that the steering wheel module (SWM) was not transmitting on the CAN network. Any diagnostic trouble codes that are stored should be fault traced first.
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. If the trouble code was stored when battery voltage was low and engine speed was close to 0 RPM when the fault occurred, it could indicate that the fault arose when the vehicle was stationary with the ignition on for a long period, thereby draining the battery, or that the fault arose due to battery voltage becoming low when the customer started the engine. At start, battery voltage may be low if the battery has been poorly charged. Check the speed at which the vehicle was travelling when the trouble code was stored as cruise control can only be activated at speeds above 30 km/h (18.6 mph).
For markets where the upgraded software, released during 2006 or later, is available, the solution may be to load the upgraded software. If the frozen values indicate that the diagnostic trouble code was generated due to low battery voltage during or just after engine start, new software is the solution. This is because the new software requires vehicle speed to be greater than 25 km/h (15 mph) for the test to be active.
If upgraded software is not available and the frozen values indicate that the fault occurred when battery voltage was low and engine speed was close to 0 RPM, fault tracing should focus on checking the vehicle's power supply, especially battery charge status.
HINT: Using VIDA vehicle communication, check that the parameters "Cruise control resume", "Cruise control SET-" and "Cruise control SET+" indicate the correct values. To aid fault tracing, use Component specifications when measuring and checking relevant components and use Wiring diagram, Signal description and Breakout box to measure and control signals to and front the control module or its components.
Remedy as necessary.
Other information
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, but if the electric cooling fan is running you have to wait another two minutes after the cooling fan has stopped, to ensure that Electronic throttle module (ETM) is 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.
- Continue
Refer to Information