Subaru Cruise Control Information – R J Engineered Solutions

Subaru Cruise Control

With any of the cable throttle Subaru engines, despite sharing the vehicle speed signal and a few other connections with it, cruise control (when fitted) was not part of the engine management, but a stand-alone system. Subaru used four different cruise control systems on the EJ and EZ series cable throttle engines, any of which can be used in VW conversions, although some are easier to use in VW’s than others.

If your donor Subaru didn’t have cruise control, but you want it in your VW conversion we usually have the wiring in stock, and maybe some of the hardware. You’ll have to source the other hardware (we rarely have all of the hardware available).

If we’re doing the wiring harness work for your VW conversion, we need to know up front if you want to use the Subaru cruise control, for two reasons. Firstly, so that the cruise control wiring can be salvaged (to extract the engine management wiring from the Subaru harnesses, all non engine management circuits including cruise control (if not required) get cut away). Secondly, we build the cruise control wiring into a separate harness which plugs into the engine management wiring to get the power and other signals required, and we only add the necessary connector to the engine management wiring when the customer is using Subaru cruise control, or wants to in the future.

Subaru cruise control controls in a VW

All of the cable throttle Subaru cruise control systems had two controls for the driver. An on / off switch in the dash which also has the ‘cruise control on’ light built in, and a stalk in the steering wheel which provides all of the other controls (RES / CANCEL / SET or ACC RES / CANCEL / SET COAST depending on which system is used – the earliest system doesn’t have the speed increment decrement feature).

Without a squib / ‘clock spring’ to connect multiple wires to the steering wheel like modern cars have, fitting the stalk to the VW steering wheel is not an option, so it cannot be quite as ‘at your fingertips’ as it was in the Subaru steering wheel (at least not while still looking neat). There is only really one location where the Subaru stalk can be fitted in the VW. However, there are quite a few options when it comes to which Subaru controls to use, and how to fit them into a T25/T3/Vanagon.

Subaru Cruise Control controls in a VW – the neatest option

This is the neatest option as it combines the stalk, on / off switch and on LED into a modified stalk from a later Subaru model – no other visible cruise control parts are needed. As standard, the stalk from the later model is not electrically compatible wit the earlier systems at all. They require extensive modification to make them electrically and functionally identical to the parts from earlier models, and this extra work plus the need to source a stalk which was not in the donor car makes this option more expensive. However, it is significantly neater than any of the other options (note the LED is not shown in the picture below, but is included). This option is only compatible with the Jideco vacuum actuation and Jideco electric actuation cruise control systems:

*Cruise Control Controls – The Neatest Option:* Combined stalk on / off and on LED (not shown) in a modified stalk from a later (incompatible) Subaru model

Subaru Cruise Control controls in a VW – the cheapest option

The simplest / cheapest option is to use the Subaru controls from the Subaru which donated all of the other cruise control components – i.e. the separate on / off switch and stalk. This option comes with all mounting parts required, and the only VW modification needed is also to cut a hole in the upper steering column shroud to the template provided. However, a vacant VW switch location for the on / off switch is also needed. This can either be in the bank of switches to the right of the instruments, or in the upper column shroud designed for the VW heated seat switch (251 953 515 A 01C):

The instrument cluster location requires no parts or modification to VW parts. It does require filing about 0.25mm from the springy locking tab on the switch.

Both locations fit with the type of Subaru Cruise control on / off switch shown here (the most common one), but Subaru used numerous other switch designs in other models, many of which are less suitable (they had very different shaped buttons)

Unfortunately the ‘Cruise’ text on the switch ends up vertical in both locations, and can’t be rotated. That’s a small price to pay for the switch fitting with no modifications to the VW parts though. This simple / cheap method is perfectly functional, but our combined stalk / on / off switch / LED is much neater.

Our Subaru cruise control wiring harness work for the VW T25/T3/Vanagon also includes most of the other mechanical parts needed to complete the installation:

Pedal switch brackets to suit whichever combination of pedal switches you are using
Pedal switches if you don’t have them or only have one but need two (as with an auto Subaru donor going into a manual VW), at extra cost
T25/T3/Vanagon cruise control stalk bracket and screws
T25/T3/Vanagon upper steering column cutout template
On / off switch adaptor for the column shroud location (i.e. in the VW heated seat switch location) if required, at a small extra cost
Actuator bracket (Jideco electric actuator system only)

ADD PHOTO SHOWING ALL OF THE ABOVE PLUS THE HARNESS ONCE PRODUCTION BRACKETS AVAILABLE

Subaru Cable Throttle Cruise Control System Types:

Subaru used the following four different cruise control systems on the cable throttle engines:

Vacuum actuator, manifold vacuum. Hardware manufactured by Jideco and Unisia. Used in the SVX and some early ‘90’s Legacies. This system can probably be used in T25 / T3 / Vanagon conversions.
Vacuum actuator, manifold vacuum via a non return valve and vacuum reservoir. Manufactured by Mitsubishi. The actuator looks like a mini brake servo with a metal casing, and has the solenoid control valves built in. Used from about MY93-96. This system can be used in T25 / T3 / Vanagon conversions.
Vacuum actuator, electric vacuum pump. Manufactured by Jideco. This system uses an engine bay mounted electric vacuum pump / valve, connected to a remote vacuum actuator with a hose. This is similar to the Hella system that VW used in the T25/T3/Vanagon and many later VW’s and models from other manufacturers. Used from about MY97-99. This system can be used in T25 / T3 / Vanagon conversions.
Electric actuator. Manufactured by Jideco. This system is simpler and neater than either of the vacuum systems. Used from about MY00-07. This system can be used in T25 / T3 / Vanagon conversions. However, not all of the cruise control ECU’s for this application can be used in VW applications. Those which cannot have to be swapped for other part numbers – they’re usually inexpensive, and sometimes we have them in stock. If you’re adding cruise control to an engine from a car which didn’t originally have cruise control, we recommend you use this system. Parts are easier to find, and it has the desirable speed increment / decrement function which systems 1 and 2, above, did not. The hardware needed from the donor Subaru for the Jideco electric actuator system is as shown below:

4. Jideco electric actuator Subaru cruise control hardware

In a Subaru, cruise control is never a separate wiring harness – it is always built into the main harness which runs across the width of the car under the dash, containing all the other circuits in the car. Some Subaru models without cruise control do have the necessary wiring (these are mostly from Forester models with the Jideco vacuum pump system), but most don’t.

There is a lot more detail about Subaru cruise control in VW’s is included in the FAQ below:

Subaru cruise control is designed to work between 25 mph and 90 mph (40 – 145 km/h). This is not the same between manufacturers, but there usually is a minimum. The minimum speed may not be exactly the same in a Subaru powered VW. Because of the way that the vehicle speed signal is created in a Subaru powered VW’s, the signal may not correspond to exactly the same vehicle speeds as it did in the Subaru. For the engine management, this does not matter (within reason), as long as the signal stops at zero speed and varies in proportion to speed. For Subaru cruise control in a VW, the signal does not have to exactly match the speeds it represented in the Subaru, but it may need to be closer to correct than if it were only being used by the engine management. Usually it is close enough, but this depends on your application, as shown below:

Subaru Cruise Control in VW Minimum Speed Examples:
Model:	Tyre:	km/h	mph
Subaru		40	25
2wd	185/82 r14	48.8	30.3
2wd	195/50 r14	58.3	36.3
2wd	225/50 r 17	48.9	30.4
Syncro	185/82 r14	24.4	15.2
Syncro	235/85 r16	19.9	12.4

The accuracy of the speed signal depends on tyre rolling radius (2WD) or final drive ratio and tyre rolling radius (Syncro). If not, a speed signal calibrator will be required. In a Syncro the speed signal is less likely to be accurate enough, so a speed signal calibrator is more likely to be required.

Cruise control is more sensitive than the engine management to a speed signal which does not match not the speeds Subaru intended because cruise control has a minimum speed which it will not work below (40 kph / 25 mph). If the inaccuracy means the speed signal says ’25 mph’ at a higher actual vehicle speed – the sort of speed that you would typically use cruise control, this can be annoying if it prevents you using cruise control until a higher than normal speed, but is easily solved by adding a speed signal calibrator.

As standard, no, for a few reasons. The ways the multi-function switches inside Subaru and VW cruise control stalks is very different. The switches in the Subaru stalk are multiplexed to so the minimum number of wires going to the steering wheel are needed, and VW’s unusual use of a 2 position slide switch for on / off (and mechanical interlocking of the switch functions on later models). Also, as well as being super rare, the VW cruise control stalk is not designed to be easily dismantled. These combine to mean it is not practical to modify the VW cruise control stalks to make them compatible. The same applies to the Golf MFA switch – it is not practical to modify to control Subaru (or VW) cruise control for the same reasons.

Yes, but not directly. The ‘drive by wire’ throttle Subaru engines have the cruise control on / off switch combined into the end of the stalk, However, electrically they function very differently to the stalks used in the Jideco cable throttle systems. However, unlike the VW T25/T3/Vanagon cruise control stalk, the Subaru cruise control stalks with the on /off button in the end are dismantleable. We can recycle the housings and switch mechanism from this later combined Subaru stalk, and replace all of the internal electronics to make it functionally identical to the stalks for the Jideco cable throttle cruise control systems, except with the cruise control on / off button at the end of the stalk.

This is by far the neatest way to install the Jideco cable throttle cruise control systems into the T25/T3/Vanagon, but requires a stalk which was not in the Subaru engine donor, which then has to be modified. We also make the mounting parts for this stalk in the VW steering column, and it firs after cutting one hole in the VW column shroud moulding, but no other modifications to VW parts.

The T25 / T3 / Vanagon has relatively ‘normal’ pedals, in that the entire pedal system is inside the passenger cabin, like Subaru’s and most other modern vehicles. This means that the pedal switch system doesn’t need to be weather proof. All older VW buses have pedal systems which are mostly outside the passenger cabin, under the floor, with just the arms supporting the pedal pads coming inside the cabin through holes in the floor. There is no way to neatly mount the pedal switches for cruise control inside, in the dry. Switches could be mounted under the floor near the pedal pivot shafts, but this would require weatherproof switches (IP67 minimum). If all of the earlier bus models used the same pedal arrangement, developing a neat, well engineered weatherproof pedal switch arrangement for them would be worthwhile. However, the German built bay window bus models alone used 6 different pedal system designs. As cruise control is a relatively niche requirement for VW engine conversion customers, the effort to develop numerous weatherproof pedal switch systems is hard to justify.

Combine this with having seen examples of customers attempting to build pedal switch systems for pre T25 / T3 / Vanagon models which are entirely unsuitable (typically non weatherproof despite our explaining up front that they have to be), we don’t want anything to do with cruise control systems in VW’s which there is any possibility of the customer installing them in an unsuitable way. For the same reason we won’t Supply Subaru cruise control systems for your VW conversion which are incomplete. For example, with no clutch pedal switch parts included, as the customer want to fit their own. We supply the wiring complete with pedal switch connectors and brackets to suit specific combinations of switches only.

As cruise control is a system which takes over control of the engine’s throttle, it is always designed very carefully to only do so when it should, and is designed to be failsafe, usually by having redundant safety systems built in to ensure that it always releases the throttle when it should. The pedal switches are a critical part of this, as they ensure the cruise control disengages as soon as you touch the brake or clutch pedal. Without them, the throttle would remain open after you have pressed the brake or clutch pedal, either interfering with gear changes, or even limiting deceleration while braking. Do not every bypass the brake and / or clutch pedal switches!

The table below shows what components are a part of each of the Subaru cable throttle cruise control systems:

System Manufacturer:	Unisia	Mitsubishi	Jideco	Jideco
Actuator type:	manifold vacuum	manifold vacuum	electric vacuum pump	electric motor (no vacuum)
Used (European Subaru models, approximate):	MY92-97 (SVX)	MY93-96	MY97-99	MY00-03 (L) MY00-07 (I,F)
ECU	Y	Y	Y	Y
Wiring harness	Y	Y	Y	Y
On/ Off Switch	Y	Y	Y	Y
Steering wheel stalk	Y	Y	Y	Y
Clutch pedal switch *	Y	Y	Y	Y
Brake pedal switch	N	Y	Y	Y
Vacuum reservoir	?	Y	N	N
Non return valve	?	Y	N	N
Actuator / valve block / cable (looks like a miniature brake servo)	N	Y	N	N
Vacuum pump / valve block	N	N	Y	N
Vacuum actuator / cable	Y	N	Y	N
Electric actuator / cable	N	N	N	Y

* If your cruise control system is from an automatic model you will need to source a clutch pedal switch to use it in a manual VW, or we can supply one if doing your cruise control wiring work.

You can use any of the following as the clutch pedal switch:

Subaru clutch pedal switch 83281AA000. This switch has a blue socket. The near identical looking Subaru switches with black or brown sockets are not suitable. This is the switch you should already have if your Subaru cruise control came from a manual model.
Subaru brake pedal switch 83370AA001. This is another of the 4 terminal brake pedal switches, as used on the brake pedal in all models with cruise control (only).
VW clutch / brake pedal switch / valve 811 907 343 B, as used in all T25 / T3 / Vanagon models with cruise control, various other VW and Audi models with cruise control, and various non VW models which used the same Hella cruise control system (e.g. various Rover / Range Rover)
We stock another switch which is functionally identical to Subaru 83370AA001, but from another vehicle, and far more readily available and better priced. This can be used as either the brake or clutch pedal switch in VW conversions. If we’re doing your cruise control wiring work and you don’t have enough pedal switches, we add these at extra cost (they’re not expensive and come with all the necessary installation parts) because we won’t supply the cruise control systems incomplete.

If you have the pedal switches but don’t send them with the wiring, we need to know which of the above switches you will be using so we can fit the correct connector(s) to the harness and include the correct pedal switch bracket(s).

Possibly, yes. You’ll have to source all or almost all of the necessary cruise control hardware from another Subaru, but we usually have stock of Subaru cruise control wiring and sometimes some of the hardware, but rarely all of it.

You can use whichever you can most easily source all of the hardware for. However, we recommend using the Jideco electric system, as the hardware for them is more readily available (cruise control became standard in more models, or a more common option in later models), it’s a slightly neater system (no vacuum plumbing required), and we include the brackets to mount all of the necessary hardware in the VW engine compartment (with either of the vacuum systems, you’ll need to make your own actuator / vacuum pump mounting brackets, and also come up with your own control stalk mounting arrangement if you use the Mitsubishi manifold vacuum system).

Yes, but we’ll need your Subaru engine management wiring harness back. The ECU end of it will have to be partially dismantled so the cruise control power supply wiring can be added and a connector added for the cruise control harness to plug into, unless you requested we add this at the time of the engine management wiring work, anticipating fitting cruise control in the future.

Yes, as long as your donor Subaru had cruise control. Cruise control is a much simpler system in models with ‘drive by wire’ throttles – it’s basically just an additional switch (the cruise control stalk, which included the on / off switch in these models) and software in the ECU. As with the cable throttle cruise control systems, you may need a speed signal calibrator if the speed signal is not a close-ish match to the speed that they system expects to see. You will also have to fit the ‘cruise control on’ LED in your dash somewhere, as this was originally part of the Subaru instrument cluster.