Thread: Hawkeye codes

Hi Damien,

Glad you're getting in their and working on your beastie yourself and using a diagnostic tool to aid in your works.

Just a couple of quick questions.

Is the 4021 error code for the tool itself or does it come up as a result of interrogating one of the ECUs? I have seen/heard of 4021 showing up as an ABS fault code.

If the error relates to the tool itself, have you run all the self diagnostic routines to see where the error may point to?

I apologise if that sounds pretty basic. I'm just trying to establish a starting point for further analysis of the error.

Let us know please.

Cheers,
Iain

yea its an abs fault some thing to do with the throttle position. Thats all i know and i dont know how the throttle position would relate to the abs.

Well the short answer is, it's all interconnected. All the ECUs talk to each other.

As to the 4021 code for the ABS relating to throttle position.

The ABS relies on the wheel speed sensors to operate correctly, this is the means by which it determines if a wheel has stopped turning at the same speed as the others (ie locked up) and triggers the system to release brake pressure to that wheel.

This system is also used by traction control in a similar way to determine if a wheel is travelling faster than the others (ie spinning) so that it can trigger the ABS system to apply the brakes to that wheel.

Now because the DSC on some vehicles also use these sensors as feedback loops to the EMS ECU to do things like cut the throttle if the vehicle becomes unstable and trigger braking differences to attempt to correct the posture of the vehicle (ie correct for potential oversteer and understeer situations).

So the throttle position is monitored to provide part of the calculation for vehicle speed. It knows what gear the vehicle is in (the EAT ECU), it knows how fast the engine is turning (EMS ECU), it knows how much fuel is being consumed (EMS ECU), it knows how fast the vehicle is travelling (ABS ECU via WheelSpeedSensor input). It therefore has a rough idea of how hard the throttle is being pressed, so its tried to self check by interrogating the TPS via the engine ECU.

Now if it gets a wildly different response than it expects, just like most other errors it will flag a temporary fault and continue doing what it does. If it finds the same situation repeatedly it will flag a "permanent" fault. This is the same process for most fault situations.

So, what does all of this really mean. Well it could be the TPS is flaky, but if you're not seeing other "throttle" related codes from other ECUs then its not as likely. It could be a wheel speed sensor is giving dodgy readings. In this case you may see other errors that relate to a particular sensor (it can usually tell which one unless its more of a communication type of error somewhere further along the chain).

I'd see if you have any other codes relating to Wheel Sensors from any other ECUs.

Note the codes, clear the codes, go for a bit of a drive and see which ones get flagged next.

In D2s this error has been known to show up at a similar time to the dreaded Three Amigos error in the SLABS system.

If you're not seeing/feeling any obvious problems in the car it could be you had a poor connection to the wheel sensor, or perhaps got a bit of moisture in the connector.

If the error doesn't come back that may be all it was. If the error does come back, by clearing all the faults (after recording what they were), you'll have provided a clear slate to diagnose further. As these systems are quite complex, sometimes one error can be masking another.

Happy hunting,
Iain