It’s not likely that Daihatsu would build a vehicle around an updated replacement part. In other words, to unnecessarilly alter an entire vehicle production, in order to suit a relocation of an electric motor placed on the column would be wastefull and rather daft.
Just to be sure, I would try locating either a Hijet or a Piaggio Porter of that vintage and then measure the one rack against the newer issue.
I have one of those column-mounted power assist units on my Suzuki Wagon R. I simply disconnected it, in order to get preciser road feel. While it was still connected, I needed to constantly correct the steering at speed, as if the unit wasn’t sure of what it was doing. In other words, you might be better off just keeping it disconnected or setting it up so that assist would only be available at lower speeds needed for parking
I think you can buy universal EPAS kits which fit to the column of any vehicle (within reason…) - whats the SITREP at the rack? Are you able to get a look at whats going on there?
As a quick test, can you disconnect the drive belt to the PAS pump and then go for a short drive? I suspect the drive belt also drives the alternator so fully charge the battery then only go a short distance with minimal electrics turned on.
Basically, see if it can be driven/steered with the PAS pump disconnected. I suspect it will be heavy, but drivable once over walking pace. Assuming so, then an aftermarket, column-mounted EPAS motor ought to be able to be retro-fitted.
These kits are moderately popular here in the UK for classic cars which never had PAS as an option, some of the 1970s cars with FWD and wide tyres can be quite a workout at low speed without PAS - I imagine that your hijet probably has fairly skinny tyres, and not a massive amount of weight over the front axle so you might be able to retrofit one of these sort of kits and not kill the EPAS motor with the effort of having to move a PAS rack and fluid with no PAS pump?
This is one example, but there are many out there
If I have misunderstood and the early models have EPAS assistance at the rack, can you disconnect it and try driving (or even just dry steering left to right, not moving forward) to see what the status is? i.e
impossible to move steering wheel
hard to move steering wheel, but eases up with speed
hard to move steering wheel at all speeds
I’m fully prepared to be wrong, but I have a feeling that Daihatsu won’t have built a bespoke system for the hijet. I suspect its some sort of development of an earlier steering rack to add additional assistance, and this might be removable - especially if its EPAS assistance because its unlikely to be near any hydraulics. If its pump-driven PAS then its harder to disconnect from the steering system, but WILL be driveable with the pump disconnected, it’ll just be heavy AF because you’re having to fight against the hydraulic fluid in the system as well as the friction of the tyres/road.
I’ve driven a Toyota Yaris (Vitz?) with a disconnected PAS pump, because the AC compressor had seized and the PAS pump and AC compressor run off the same belt. It was a workout, but driveable.
The symptom was: stuttering of the electric power steering motor while the car is stationary. Then after excersizing the steering for 20 seconds the EPS light would come on in the dash and the EPS would altogether stop working.
I removed the rack to gather further details about how the system works, but also because I noticed the rust damage ontop of where the rack was that I didnt want to linger.
I have since cut out the damaged unibody sections and am trying to penetrate the area with a product called corrosion free that has good reviews in my area.
I plugged the rack in and attempted to steer the rack via the input shaft with it on my lap to get a good feel for what was happening, but it was as if the car knew the rack was in my lap. The EPS light never came on but it certainly did not feel like there was any assist.
I reinstalled the rack and now the EPS light comes on right away as soon as you steer the wheel.
The car is driveable without EPS, just a bit heavy.
Then as if by miracle after a day of driving, like flipping a switch the EPS all the sudden started working and has been working fine all evening.
I wonder if because the battery died while shipping, the EPS computer lost it’s data and needs a reset proceedure or time to gather data. I’ve got no idea, but I’ll cross my fingers and hope it keeps working!