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Review of AusCruise Drive-By-Wire Cruise Control
author: Martin "mpot" Pot
published: 14 February 2007
This review looks at an Autron AusCruise after-market cruise control
which was recently installed in a 2004 Toyota Tarago GLi.
A description of the initial performance issues is provided, along with
details on how the issues were resolved, resulting in a
well-performing cruise control.
Background
My previous cars (1989 Nissan U12 Pintara Ti,
2000 Mitsubishi TJ Magna wagon) both have
a factory-fitted cruise control.
Once you are used to cruise control in a car, you don't want to do without it....so
I decided to get a cruise control fitted to my newly purchased 2-year-old Toyota Tarago GLi.
Apparently it's not feasible to get a Toyota factory cruise control retro-fitted to a GLi
(as fitted to the Tarago GLX), so I had to look at aftermarket cruise controls.
One additional complexity is that the Tarago has a drive-by-wire accelerator.
Cruise Control and Drive-by-Wire
On a car with a drive-by-wire accelerator, instead of the accelerator pedal being connected to the
engine's throttle via a mechanical cable,
an accurate position sensor is used to transmit the pedal position to the ECU.
The majority of cruise control systems use mechanical means to operate the accelerator pedal
(referred to as "pedal pull" systems), but on a car with a drive-by-wire accelerator,
the cruise control system needs to integrate directly with the ECU.
Autron (the makers of the AusCruise cruise controls) provide more background
information on drive-by-wire on their website here.
Features of the AusCruise Cruise Control
The AusCruise drive-by-wire cruise control has been designed, developed and
built in Australia, by Autron Electronics,
who have over 26 years experience in automotive design.
The cruise control module uses a microprocessor to monitor the car speed, and
control the throttle to maintain the set speed.
It features a steering-wheel-mounted control unit, which communicates with
the cruise control module by multiplexing signals over the horn wire in the steering wheel.
Earlier versions of after-market steering-wheel-mounted controls typically
were battery-powered, and relied on either RF signals or infrared to
communicate with the cruise control unit in the dash.
However, these units could suffer from intermittent communications, and would
periodically require new batteries.
Many features of the AusCruise system are programmable, including the minimum and maximum speed,
tap-up and tap-down steps, and many other parameters.
However, these are not user-programmable, but can only be adjusted by
a licensed installer who has
the Handheld Diagnostic & Programming Tool.
Note that the AusCruise cruise control units only have a three month warranty,
although an extended warranty can be purchased.
Installation
The cruise control was installed in my 2004 Tarago by
Ashley Electrical, a local company who
specialises in automotive electronics and security, and have a number of mobile technicians.
Initial impressions were good, with the installation looking very neat.
Immediately visible was the pod containing the controls, which had been mounted
on the lower right hand side of the steering wheel.
HW100U steering wheel controls
A status LED had been mounted on a blank switch plate on the right-hand side of
the dashboard.
status LED mounted on the dash
Digging deeper, there are two separate modules installed underneath the dashboard,
hidden behind the gearstick on the left-hand side of the steering wheel.
All wiring to these modules has been neatly taped up, and a fuse for the cruise control
is visible on the right-hand side of the photo below.
two modules under the dash
Closer examination indicates one module is labelled as the "Cruise Control Module", while the
second is labelled the "Electronic Actuator".
The first contains the microprocessor for handling the cruise control, and the second
provides the interface to the car's ECU.
Cruise Control module and Electronic Actuator module
Operation
The cruise control functions in a very similar manner to most of the factory-fitted
cruise controls I have used.
Firstly, the cruise control must be turned on using the "On/Off" button on the
steering-wheel-mounted controls.
This will result in the status LED going green.
Once turned on, when the car is moving at the desired speed,
hitting the "Set" button will engage the cruise control, and the
status LED will go orange.
The "Acc" and "Dec" buttons can be used to increase and decrease the
set speed. A single click of either button will increase or decrease
the speed by 1 km/h, and holding down either button will cause the
cruise control to continue to accelerate or decelerate.
The cruise control will be dis-engaged when you hit the brake pedal,
but will stay on, with the status LED turning green.
Alternatively, it can be turned off by hitting the "On/Off" button,
which will also turn the status LED off.
(On cars with a manual gearbox, hitting the clutch will also dis-engage the
cruise control.)
To resume a previously set speed, when the car is doing at least 30-40 km/h,
and the cruise control is on (ie, the status LED is green),
hit the "Res" button, and the cruise control will be re-engaged
(turning the status LED orange),
and will accelerate to the previously set speed.
Note that the AusCruise cruise control will remember the set speed
even when you turn the ignition off.
Every other cruise control system I have used will forget the set speed
as soon as the ignition is turned off.
One feature that I do miss is a "cancel" button.
All other cruise control units I have used have a "cancel" feature, where
you can dis-engage the cruise control without turning it off.
This can be useful if you are driving in the country, and are approaching
a town, and need to slow down to an urban speed limit while passing through
the town.
I'm used to using the "cancel" feature to dis-engage the cruise control
prior to reaching the lowered speed limit, and coasting down to
that speed without using the brakes.
The only way to do this with the AusCruise is to either hit the brakes
(which will dis-engage the cruise control, but leave it turned on),
or hit the "On/Off" button (which will dis-engage and turn off the cruise control).
However, if you hit the "On/Off" button, then after passing through the town
(or stop sign or traffic lights),
to re-engage the cruise control, you first need to turn it on again (by hitting "On/Off"),
and you can then resume your previously set speed with the "Res" button.
While this isn't a big issue, I am used to the "cancel" feature of the cruise control
in my two previous cars, and hence miss it with the AusCruise.
Too often I find myself hitting the "Res" button, only to
find it has no effect because the cruise control was turned
off (when I hit the "On/Off" button), when I only wanted to dis-engage it.
I have now reverted to hitting the "On/Off" button twice when I want to coast,
as the first click will dis-engage and turn off the cruise control, and the second
click will turn it on again (but will not engage it), thus allowing me
to easily resume the set speed with a single click on the "Res" button soon after.
Performance
When driving the Tarago for the first time after the installation of the AusCruise,
my initial impression was not very good!.
The acceleration performed by the cruise control was far too slow, so attempting
to resume to a higher set speed would take a long time.
Similarly, holding the "Acc"
button to get the cruise control to accelerate the car was also extremely slow.
Maybe other people would accept this very poor performance, but to me, it was
unacceptable.
Reprogramming
Ashley Electrical sent a technician later the same day, to check out my complaints
about the performance of the cruise control.
Because the AusCruise has so many programmable settings, it should have been
relatively straight forward to adjust the behaviour to suit the car.
However, the technician didn't have any documentation describing the various
programmable settings.
Using the Autron Handheld Diagnostic & Programming Tool, the technician
tried tweaking various settings, and I tested the change in behaviour
by driving the car around the block numerous times.
(The loop acceleration constant was increased from 1.2 to 1.4;
the initial acceleration was increased from 7 to 11;
and the acceleration constant was increased from 4 to 6.)
The changes improved the acceleration rate of the cruise control,
but caused a lot of overshoot when resuming a set speed, or when just
setting the speed (the cruise control would overshoot by ~10km/h, before
slowing down to the required speed).
In the absence of any further programming details (Autron's office was already closed for the day),
the technician agreed to discuss the issues with the manufacturers, namely Autron.
Later that week, I received a phone call from the CEO of Autron, and after describing the
performance, he agreed that the default settings didn't suit the Tarago, and it would
require some tweaking.
The Autron developers provided some recommended settings, and a technician from
Ashley Electrical was dispatched to make the appropriate changes to the cruise control
in my Tarago.
Before making any other changes, all settings that had been previously modified were reset
to their default values.
Autron recommended increasing the loop acceleration constant from 1.2 to 1.5,
but after testing the performance, it was increased to a value of 1.8.
This change provided much better acceleration when resuming a higher set speed,
and also when holding down the "Acc" button to accelerate.
This change has not introduced any overshoot when resuming a higher set speed,
and hitting the "Set" button results in the cruise control maintaining the required speed
without first overshooting.
While not providing quite as much acceleration as the factory-fitted
cruise control in other cars that I have driven, the performance of the AusCruise
is now acceptable.
Summary
I'm quite happy with the AusCruise cruise control in my Tarago.
Once the initial performance issues had been resolved with some re-programming,
the performance is quite good.
The steering-wheel-mounted controls are easy to use, and the dash-mounted
LED provides an indication of the current status of the cruise control.
Both Autron and Ashley Electrical have been helpful in resolving the
performance problems.
I miss a "cancel" button, and would like to see the "On/off" button
on the steering-wheel controls replaced with a "Cancel" button,
and the "On/off" button moved to a dash-mounted switch.
However, I think I'll just have to get used to the lack of a "Cancel" button.
I find the status LED a little difficult to see in bright sunlight, and it can
be a bit too bright at night.
Connecting the LED into the dash light circuit to provide dimming functionality
when the headlights are on is not very complex, and could easily be implemented.
References
last updated 3 Oct 2012
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