Checking components

Check whether the engine control module (ECM) has stored any other diagnostic trouble codes that indicate a fault in the pulse width modulated (PWM) signal or the analogue signal from the accelerator pedal position sensor.

If ECM-9180, ECM-9520, ECM-9530 and/or ECM-9540 are stored, these diagnostic trouble codes are to be fault traced first. Otherwise, continue as follows.

Using the diagnostic trouble code counter, check whether the fault is intermittent or permanent. Compare the parameters "Accelerator pedal, Analogue" and "Accelerator pedal, PWM". These should under no circumstances differ by more than 5% unless the analogue signal is undergoing change, e.g. during throttle application, when a large deviation between the two signals is permitted.

If the diagnostic trouble code (DTC) is permanent: 

Search for a fault that could cause any of the signals to be faulty yet still within the electrical fault limits. Check the cables and connections between the accelerator pedal position sensor and the engine control module (ECM) for contact resistance and corrosion.

Check whether there is any potential difference for ground connections and voltage supplies between the engine control module (ECM) and the accelerator pedal position sensor.

Check the cables and connections between the grounding point for the system relay and the accelerator pedal position sensor.

If the diagnostic trouble code (DTC) is intermittent: 

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. The operating conditions can be, for example, whether the engine was running, what the speed of the vehicle was and what the battery voltage in the system was. This information can facilitate searching for an intermittent fault. If the trouble code was stored when battery voltage was less than 10.5 V and engine speed was 0 rpm, it indicates that the fault may have occurred when the engine was started. This, in turn, indicates that the battery's charging status is not OK.

• Check the battery status.

HINT: Using VIDA vehicle communication, check that the parameters "Accelerator pedal, PWM", "Accelerator pedal, PWM (via ETM)" and "Accelerator pedal, Analogue" indicate 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. 

When ECM-958F is stored, the frozen values often indicate that the fault occurred when battery voltage was less than 12 V and engine speed was close to 0 rpm. If these operating conditions are found in the vehicle and upgraded software is available (released 2006 or later), the solution is to download the upgraded software. The upgraded software requires engine speed to be greater than 600 rpm for the test to be active.

Upgraded software could also be the solution if the trouble code was stored when the engine was running since detection time has been increased from 0.4 to 0.7 seconds. The upgraded software will also be much more tolerant to short, intermittent disruptions. 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.

Remedy as necessary.

Other information: 

• To access or replace the system relay, see the location of components
• To access or replace the accelerator pedal (AP) position sensor: Replacing the accelerator pedal module
• See Checking wiring and terminals
• See Identifying upgraded software ECM/ETM
• See Checking wiring and terminals

Caution: In order for Electronic throttle module (ETM) to reset any reconfigurations as well as delete internally stored problems, the following must be performed:

• Turn off the ignition and then wait three minutes for the main relay or system relay to release the voltage feed to, among others, 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.

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